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MPLS-TE Troubleshooting: Flooding and Topology Issues

 

 

Introduction

This document provides hints, tips and how-to information on debugging MPLS-TE issues related to the topology and flooding TE information between routers. This is intended to assist users with debugging such issues in their own networks, and to help ensure that appropriate diagnostic information is provided to Cisco should support be required.

Terminology

The following terms are used throughout this document:

  • LSA: Link-State Advertisement. This is well-known to engineers running OSPF networks, but in IS-IS the term LSP (Link-State PDU) is correct for the equivalent object. LSA is used here for both protocols to avoid confustion with TE Label-Switched Paths.
  • TE showtech: the output of "show tech-support mpls traffic-eng"
  • IGP showtech: the output of "show tech-support isis" or "show tech-support isis", depending on the IGP in use.
  • PFI showtech: the output of "show tech-support pfi"
  • RSI showtech: the output of "show tech-support rsi" and "show tech-support srlg"

 

Note that all showtechs must be collected while logged in as a user with cisco-support privileges, or critical information will not be present.

 

Flooding and Topology Basics

Data Flow in IOS-XR

In IOS-XR, the TE control process and the IGPs (OSPF and IS-IS) are separate, and maintain their own copies of data they require. Under normal operation, the usual flow of information and data between TE and the IGPs is:

  • The IGP tells TE which adjacencies are up for each area. TE is not aware of adjacencies that are not fully established.
  • TE generates a local LSA to be flooded into each area
  • The IGP floods the local LSA into the topology on TE's behalf
  • The IGP passes all TE topology information it receives from all nodes in the network to TE, including the information generated by the local TE process
  • TE uses this topology to calculate tunnel paths

 

Understanding this data flow is essential to accurate diagnosis of flooding and topology issues. It's also very helpful when requesting support from Cisco if the problem has already been isolated as far as possible; this decreases the time it takes for issues to reach the appropriate team.

 

Please note that this page is arranged in order of this data flow. However, when debugging an issue it's more usual to work backwards. As an example:

  • we notice that a tunnel is down
  • we discover this is because an address on its path isn't in the topology
  • this in turn is because the link isn't flooded
  • the link isn't flooded because the interface is down.

 

There's no reason to use this page in the order it's written if that's what works for you!

 

Show commands

There are a number of show commands which are very important in the  investigation of flooding and topology problems, so it's a good idea to  be familiar with them. These are:

  • General:                                              
    • show mpls traffic-eng igp-areas gives general information about the IGP instances and areas that are known to TE
  • Interface/neighbor data                                            
    • show ospf neighbor displays the OSPF adjacencies which exist
    • show isis neighbors and show isis adjacency give information about IS-IS adjacencies.
    • show mpls traffic-eng link-management interfaces gives information about the state of each link known to TE.
    • show mpls traffic-eng link-management igp-neighbors displays what TE knows about each IGP-neighbor
  • Status of local LSA                                              
    • show mpls traffic-eng link-management advertisements displays the local LSA that TE has flooded to each IGP-area.
    • show isis mpls traffic-eng advertisements displays the local LSA that ISIS has flooded to each of its areas
    • show ospf mpls traffic-eng link displays the local-LSA data that OSPF has received from TE, and show ospf mpls traffic-eng fragment shows the LSA fragments that are being flooded to the network
  • Complete topology                                             
    • show isis database verbose displays the topology in IS-IS. The verbose option is required to display flooded TE data.
    • show ospf database opaque-area displays the OSPF topology. The opaque-area option is required to display flooded TE data.
    • show mpls traffic-eng topology displays the topology as known to TE.

The topology commands can output a huge amount of data for large networks, so make use of the output-reduction and filter options provided.

 

If a link isn't flooded into an IGP-area, by TE, there's a several things to check. This section covers them.

 

It sounds obvious, but it's good to check this - if only to save embarrassment when someone else points it out to you

 

 

The first thing to check is that the IGP has an adjacency to at least  one neighbor over the link. When the IGP is running more than one  area/level, ensure the adjacency is up in the correct area(s).

 

OSPF

RP/0/0/CPU0:te-ma1#show ospf neighbor 
Fri Jul 23 19:37:01.564 UTC

* Indicates MADJ interface

Neighbors for OSPF 0

Neighbor ID     Pri   State           Dead Time   Address         Interface
102.0.0.2       1     FULL/DR         00:00:36    11.0.0.2        GigabitEthernet0/2/0/0    Neighbor is up for 3d22h
103.0.0.3       1     FULL/DR         00:00:34    11.2.2.3        GigabitEthernet0/2/0/2    Neighbor is up for 3d22h
102.0.0.2       1     FULL/  -        00:00:34    12.0.0.2        POS0/5/0/0                Neighbor is up for 3d22h
103.0.0.3       1     FULL/  -        00:00:35    12.2.2.3        POS0/5/0/2                Neighbor is up for 3d22h

Total neighbor count: 4

 

Check that:

  • The adjacency exists for the interface you're interested in
  • The adjacency is up (usually FULL, but see below)
  • The adjacency is of the correct type
    • P2P adjacencies will have a dash after the adjacency state
    • Broadcast adjacencies will have the neighbor's DR role, which will be DR, BDR or DROTHER
  • The neighbor's ID and address are correct
  • The adjacency is in the correct area (use the detail option on the command for this).

 

An OSPF adjacency won't be announced to TE until it's in FULL state  (i.e. database exchange has been completed). However, OSPF calculates  the neighbor uptime from when hello packets were first exchanged. This  means that if there's communication problems on the link, it's possible  to see OSPF neighbors with relatively long 'uptimes' which are still not  fully up (e.g. in EXCHANGE or LOADING state). Note also that this does NOT apply to broadcast links with multiple neighbors; in this case the expected final state is that adjacencies to the DR and BDR will come up to FULL state, but adjacencies to other nodes will only come to EXCHANGE state.


IS-IS

RP/0/0/CPU0:te-ma1#show isis neighbors 
Fri Jul 23 19:37:07.139 UTC

IS-IS 0 neighbors:
System Id      Interface        SNPA           State Holdtime Type IETF-NSF
te-ma2         Gi0/2/0/1        0090.86a9.18ff Up    9        L1L2 Capable 
te-ma2         PO0/5/0/1        *PtoP*         Up    27       L1L2 Capable 
te-ma1         Gi0/2/0/3        0002.17ef.70ff Up    24       L1L2 Capable 
te-ma1         PO0/5/0/3        *PtoP*         Up    27       L1L2 Capable 

Total neighbor count: 4

 

Check that:

  • The adjacency exists for the interface you're interested in
  • The adjacency is up
  • The adjacency is in the correct level (Type column)
  • The adjacency is the expected type (P2P or broadcast)                                                    
    • P2P adjacencies will have a SNPA of *PtoP*
    • Broadcast (LAN) adjacencies will have a MAC address SNPA
  • The neighbor's ID and address are correct (use the detail option to see addresses). Note that IS-IS will, by default, convert system IDs to hostnames.

 

If adjacencies are down (or otherwise not fully up), consult the documentation for the relevant protocol to troubleshoot further.

 

Is TE running over the IGP area?

Make sure that TE is configured to run over the IGP-area that doesn't have the links flooded.

 


 
RP/0/0/CPU0:te-ma1#show mpls traffic-eng igp-areas Tue Jul 27 18:07:20.526 UTC MPLS-TE IGP Areas Global router-id:         101.0.0.1
Global optical router-id: Not available IS-IS 0

  IGP ID:                      0001.0011.0111
    TE router ID configured:     101.1.1.1
                 in use:         101.1.1.1     Link connection:             up     Topology/tunnel connection:  up

    level 1
        TE index: 1         IGP config for TE: complete
        Local links flooded in this IGP level: 4         Flooding beacon sent and received
        P2P tunnel heads running over this IGP level: 5             1 AA, 0 FA         P2MP destinations running over this IGP level: 0         Tunnel loose-hops expanded over this IGP level: 0 OSPF 0

    IGP ID:                      101.0.0.1
    TE router ID configured:     101.0.0.1
                 in use:         101.0.0.1     Link connection:             up     Topology/tunnel connection:  up

    area 1
        TE index: 0         IGP config for TE: complete
        Local links flooded in this IGP area: 4         Flooding beacon sent and received
        P2P tunnel heads running over this IGP area: 5             1 AA, 0 FA         P2MP destinations running over this IGP area: 0         Tunnel loose-hops expanded over this IGP area: 0

 

Ensure that:

  • the IGP instance you expect is present                                           
    • If it isn't, ensure the required TE configuration is present in the IGP submode
  • The IGP ID is correct - it should be the OSPF router-id or the IS-IS system-id, which is extracted from the IS-IS NET config                                                  
    • If not, check the IGP config
  • The TE router-id is correct                                           
    • Check that the configured ID here matches the "mpls traffic-eng router-id" config in the IGP; it may be 0.0.0.0 if nothing is configured
    • If the TE router-id config references a Loopback interface, ensure that the Loopback interface exists and has an IP address. If not, the  global router-id will be used as the TE router-id instead, and the configured router-id will be displayed as 0.0.0.0.
    • If you're deliberately using the global router-id (i.e. you haven't configured "mpls traffic-eng router-id" under the IGP) ensure that the router-id in use is what you expect it to be. Be aware that the XR global router-id may change due to events such as a router reload, IP address configuration changes or interface state changes, so this isn't recommended.
  • The area you expect exists within the IGP instance
  • The IGP config for the area is OK (the "IGP config for TE: complete" line)                                           
    • If not, ensure that the area has TE enabled in the IGP config. For IS-IS, make sure wide metrics are enabled.
  • The link and topology connections are up                                                  
    • it will stay down until there's at least one correctly-configured area within the IGP-instance
  • The flooding beacon is "sent and received". This refers to communications between TE and the IGP and if it's in any other state, may indicate a communicatin problem.

 

If you're sure that the IGP config is correct, and there's problems in this area, then contact Cisco support. Both TE showtech and the relevant IGP showtech output will be required.

 

 

show mpls traffic-eng link-management igp-neighbors is a useful command to ensure that TE knows about the IGP adjacencies on each link.

 


 
RP/0/0/CPU0:te-ma1#show mpls traffic-eng link-management igp-neighbors Tue Jul 27 18:41:39.372 UTC   Link ID:: GigabitEthernet0/2/0/0     Neighbor ID: 11.0.0.2 (OSPF 0 area 1, link address: 0.0.0.0)   Link ID:: GigabitEthernet0/2/0/1     Neighbor ID: 0002.0002.0022.00 (IS-IS 0 level 1, link address: 11.1.1.2)   Link ID:: POS0/5/0/2     Neighbor ID: 103.0.0.3 (OSPF 0 area 1, link address: 12.2.2.3)   Link ID:: POS0/5/0/3     Neighbor ID: 0003.0003.0003.00 (IS-IS 0 level 1, link address: 12.3.3.3)

Note that in the case of a broadcast adjacency, the neighbor address displayed in TE will be the interface address of the DR (for OSPF) or DIS (for IS-IS), which will be the local interface address if the local router is the DR/DIS.

 

If the adjacency you expect on a link isn't present, make sure that:

  • the IGP has an adjacency;
  • TE is running over the IGP-area that the adjacency is in;
  • TE is configured to run over the link.

 

If you're running TE over IS-IS, you can also check the log of adjacency updates that IS-IS has sent to TE:

 


 
RP/0/0/CPU0:te-ma3#sh isis mpls traffic-eng adjacency-log Wed Jul 28 20:42:06.789 UTC IS-IS 0 Level-1 MPLS Traffic Engineering adjacency log When          Neighbor ID        IP Address       Interface Status --- Mon Jul 19 2010 --- 21:52:58.194  te-ma1             12.3.3.1         PO0/5/0/3 Up     21:53:06.755  te-ma2             11.5.5.2         Gi0/2/0/1 Up     21:53:12.942  te-ma1             11.3.3.1         Gi0/2/0/3 Up     21:53:35.523  te-ma2             12.5.5.2         PO0/5/0/1 Up     --- Tue Jul 27 2010 --- 19:07:27.618  te-ma1             0.0.0.0          Gi0/2/0/3 Down   19:07:51.518  te-ma2             0.0.0.0          Gi0/2/0/1 Down   19:07:54.593  te-ma2             11.5.5.2         Gi0/2/0/1 Up     19:07:54.596  te-ma3             11.3.3.3         Gi0/2/0/3 Up 

If the adjacency is present but doesn't seem to have made it to TE, make sure both TE and IGP showtechs are provided with any support request.

 

Does TE have the interface state correct?

RP/0/0/CPU0:te-ma3#show mpls traffic-eng link-management interfaces 
Wed Jul 28 18:13:10.770 UTC

  System Information:: 
      Links Count         : 8 (Maximum Links Supported 250) 

  Link ID:: GigabitEthernet0/2/0/0 (11.4.4.3)
    Local Intf ID: 25
    Link Status:

      Link Label Type     : PSC
      Physical BW         : 1000000 kbits/sec
      BCID                : RDM 
      Max Reservable BW   : 200000 kbits/sec (reserved: 0% in, 0% out)
      BC0 (Res. Global BW): 200000 kbits/sec (reserved: 0% in, 0% out)
      BC1 (Res. Sub BW)   : 100000 kbits/sec (reserved: 0% in, 0% out)
      MPLS TE Link State  : MPLS TE on, RSVP on, admin-up
      Inbound Admission   : reject-huge
      Outbound Admission  : allow-if-room
      IGP Neighbor Count  : 1
      Max Res BW (RDM)    : 200000 kbits/sec
      BC0 (RDM)           : 200000 kbits/sec
      BC1 (RDM)           : 100000 kbits/sec
      Max Res BW (MAM)    : 500000 kbits/sec
      BC0 (MAM)           : 200000 kbits/sec
      BC1 (MAM)           : 100000 kbits/sec
      Attributes          : 0x0
      Attribute Names     : 
      Flooding Status: (1 area)
        IGP Area[1]: OSPF 0 area 1, flooded
          Nbr: ID 11.4.4.3, IP 0.0.0.0 (Up)
          Admin weight: not set (TE), 1 (IGP)

  Link ID:: GigabitEthernet0/2/0/1 (11.5.5.3)
    Local Intf ID: 26
    Link Status:

      Link Label Type     : PSC
      Physical BW         : 1000000 kbits/sec
      BCID                : RDM 
      Max Reservable BW   : 200000 kbits/sec (reserved: 0% in, 0% out)
      BC0 (Res. Global BW): 200000 kbits/sec (reserved: 0% in, 0% out)
      BC1 (Res. Sub BW)   : 100000 kbits/sec (reserved: 0% in, 0% out)
      MPLS TE Link State  : MPLS TE on, RSVP on, admin-up
      Inbound Admission   : reject-huge
      Outbound Admission  : allow-if-room
      IGP Neighbor Count  : 1
      Max Res BW (RDM)    : 200000 kbits/sec
      BC0 (RDM)           : 200000 kbits/sec
      BC1 (RDM)           : 100000 kbits/sec
      Max Res BW (MAM)    : 500000 kbits/sec
      BC0 (MAM)           : 200000 kbits/sec
      BC1 (MAM)           : 100000 kbits/sec
      Attributes          : 0x0
      Attribute Names     : 
      Flooding Status: (1 area)
        IGP Area[1]: IS-IS 0 level 1, flooded
          Nbr: ID 0002.0002.0022.01, IP 11.5.5.2 (Up)
          Admin weight: not set (TE), 10 (IGP)

  Link ID:: POS0/5/0/0 (12.4.4.3)
    Local Intf ID: 14
    Link Status:

      Link Label Type     : PSC
      Physical BW         : 155520 kbits/sec
      BCID                : RDM 
      Max Reservable BW   : 200000 kbits/sec (reserved: 0% in, 0% out)
      BC0 (Res. Global BW): 200000 kbits/sec (reserved: 0% in, 0% out)
      BC1 (Res. Sub BW)   : 100000 kbits/sec (reserved: 0% in, 0% out)
      MPLS TE Link State  : MPLS TE on, RSVP on, admin-up
      Inbound Admission   : allow-all
      Outbound Admission  : allow-if-room
      IGP Neighbor Count  : 1
      Max Res BW (RDM)    : 200000 kbits/sec
      BC0 (RDM)           : 200000 kbits/sec
      BC1 (RDM)           : 100000 kbits/sec
      Max Res BW (MAM)    : 500000 kbits/sec
      BC0 (MAM)           : 200000 kbits/sec
      BC1 (MAM)           : 100000 kbits/sec
      Attributes          : 0x0
      Attribute Names     : 
      Flooding Status: (1 area)
        IGP Area[1]: OSPF 0 area 1, flooded
          Nbr: ID 102.0.0.2, IP 12.4.4.2 (Up)
          Admin weight: not set (TE), 1 (IGP)

  Link ID:: POS0/5/0/1 (12.5.5.3)
    Local Intf ID: 17
    Link Status:

      Link Label Type     : PSC
      Physical BW         : 155520 kbits/sec
      BCID                : RDM 
      Max Reservable BW   : 200000 kbits/sec (reserved: 0% in, 0% out)
      BC0 (Res. Global BW): 200000 kbits/sec (reserved: 0% in, 0% out)
      BC1 (Res. Sub BW)   : 100000 kbits/sec (reserved: 0% in, 0% out)
      MPLS TE Link State  : MPLS TE on, RSVP on, admin-up
      Inbound Admission   : allow-all
      Outbound Admission  : allow-if-room
      IGP Neighbor Count  : 1
      Max Res BW (RDM)    : 200000 kbits/sec
      BC0 (RDM)           : 200000 kbits/sec
      BC1 (RDM)           : 100000 kbits/sec
      Max Res BW (MAM)    : 500000 kbits/sec
      BC0 (MAM)           : 200000 kbits/sec
      BC1 (MAM)           : 100000 kbits/sec
      Attributes          : 0x0
      Attribute Names     : 
      Flooding Status: (1 area)
        IGP Area[1]: IS-IS 0 level 1, flooded
          Nbr: ID 0002.0002.0022.00, IP 12.5.5.2 (Up)
          Admin weight: not set (TE), 10 (IGP)

 

Make sure that:

  • The basic interface details are correct (name, IP address)
  • Link state is correct (it should be MPLS TE on, RSVP on, admin-up)
  • The bandwidths on the interface are as expected
  • The link attributes are OK, if any are configured
  • SRLGs are correct, if configured
  • Flooding status is correct:                                         
    • Link is flooded to correct area(s)
    • Neighbor id and address are correct (remember, it's the DR's link address for broadcast links, which may be the local address)
    • Admin weights are correct

 

No IGP adjacency

If there's no IGP adjacencies at all, the flooding status will look like this:

 


 
      Flooding Status: (0 area)         Not flooded: Link has no IGP adjacencies for any area

 

If the IGP shows an adjacency in an area where TE is correctly configured but TE doesn't know about it, this is a problem. TE and IGP showtechs will be required for any support request.

 

If the link is down:

 


 
      Flooding Status: (0 area)         Not flooded: Interface has been administratively disabled

If the link is up but TE doesn't know the correct state, a support request will require TE and PFI showtechs.

 

 

If the link has no IP address, note that 0.0.0.0 is displayed for the link's address. The show command also gives the reason the link isn't flooded:

 


 
RP/0/0/CPU0:te-ma1#show mpls traffic-eng link-management interfaces GigabitEthernet0/2/0/0 Wed Jul 28 18:03:36.159 UTC   System Information::       Links Count         : 8 (Maximum Links Supported 250)   Link ID:: GigabitEthernet0/2/0/0 (0.0.0.0)     Local Intf ID: 26     Link Status:       Link Label Type     : PSC       Physical BW         : 1000000 kbits/sec       BCID                : RDM       Max Reservable BW   : 200000 kbits/sec (reserved: 0% in, 0% out)       BC0 (Res. Global BW): 200000 kbits/sec (reserved: 0% in, 0% out)       BC1 (Res. Sub BW)   : 100000 kbits/sec (reserved: 0% in, 0% out)       MPLS TE Link State  : MPLS TE on, RSVP on, admin-down       Inbound Admission   : reject-huge       Outbound Admission  : allow-if-room       IGP Neighbor Count  : 0       Max Res BW (RDM)    : 200000 kbits/sec       BC0 (RDM)           : 200000 kbits/sec       BC1 (RDM)           : 100000 kbits/sec       Max Res BW (MAM)    : 500000 kbits/sec       BC0 (MAM)           : 200000 kbits/sec       BC1 (MAM)           : 100000 kbits/sec       Attributes          : 0x0       Attribute Names     :       Flooding Status: (0 area)         Not flooded: The interface does not have an IP address

 

An IPv4 address is required; IPv6-only and unnumbered interfaces can't be used by TE in XR.

 

If the link has an IP address configured that TE doesn't seem to know about, contact Cisco support. Both PFI and TE showtechs will be required.

 

 

Forward-referenced interfaces are interfaces that are configured in TE (under the mpls traffic-eng submode), but the interface doesn't exist on the router. This could be because the expected linecard has been removed or is down, or could be because of a mis-configuration in TE. In this case, there will simply be no information for the link:

 

  Link ID:: POS0/4/0/0 (0.0.0.0)
    Local Intf ID: 40
    Link Status:

      Link Label Type     : PSC
      Physical BW         : 0 kbits/sec      BCID                : RDM 
      Max Reservable BW   : 34359738 kbits/sec (reserved: 0% in, 0% out)
      BC0 (Res. Global BW): 34359738 kbits/sec (reserved: 0% in, 0% out)
      BC1 (Res. Sub BW)   : 34359738 kbits/sec (reserved: 0% in, 0% out)
      MPLS TE Link State  : admin-up
      Inbound Admission   : allow-all
      Outbound Admission  : allow-if-room
      IGP Neighbor Count  : 0
      Max Res BW (RDM)    : 0 kbits/sec
      BC0 (RDM)           : 0 kbits/sec
      BC1 (RDM)           : 0 kbits/sec
      Max Res BW (MAM)    : 0 kbits/sec
      BC0 (MAM)           : 0 kbits/sec
      BC1 (MAM)           : 0 kbits/sec
      Attributes          : 0x0
      Attribute Names     : 
      Flooding Status: (0 area)
        Not flooded: 

 

In particular, not that there's no IP address and no physical bandwidth for the link.

 

In this case, make sure the link really exists (show interface or show ipv4 interface). If you contact Cisco support, TE and PFI showtechs will be required.

 

 

If a link on which TE is configured doesn't exist in the output of show mpls traffic-eng link-management interface at all, TE and PFI showtechs will be required with any support request.

.

SRLG data is wrong

 

If TE has incorrect SRLG data for a link:

  • Make sure the SRLG config for the interface is correct
  • Check the output of  show srlg to ensure that the system has the correct SRLGs in its master record.
  • Ensure that the system has the correct SRLGs on the RP where TE is running with show srlg location <location>.

 

If assistance is required from Cisco support, both TE and RSI showtechs will be required.

 

 

The flooding status discussed in the previous section gives a quick indication of whether the link is flooded or not.  However, it may be necessary to inspect the data that has been flooded  to the IGP by TE.

 

RP/0/0/CPU0:te-ma3#show mpls traffic-eng link-management advertisements 
Wed Jul 28 18:50:44.532 UTC

  Flooding Status             : ready
  Last Flooding               : 84646 seconds ago
  Last Flooding Trigger       : TE Link came Up
  Next Periodic Flooding In   : 138 seconds 
  Diff-Serv TE Mode           : Prestandard 
  Configured Areas            : 2

  IGP Area[1]:: IS-IS 0 level 1
      Flooding Protocol   : IS-IS
      IGP System ID       : 0003.0003.0003
      MPLS TE Router ID   : 103.1.1.3
      Flooded Links       : 2

      Link ID:: 0 (GigabitEthernet0/2/0/1)
          Link IP Address      : 11.5.5.3
          O/G Intf ID          : 26
          Designated Router    : 0002.0002.0022.01, IP 11.5.5.2
          TE Metric            : 10
          IGP Metric           : 10
          Physical BW          : 1000000 kbits/sec
          BCID                 : RDM 
          Max Reservable BW    : 200000 kbits/sec
          Res Global BW        : 200000 kbits/sec
          Res Sub BW           : 100000 kbits/sec

          Downstream::
                                Global Pool   Sub Pool   
                                -----------   -----------
            Reservable BW[0]:        200000        100000  kbits/sec
            Reservable BW[1]:        200000        100000  kbits/sec
            Reservable BW[2]:        200000        100000  kbits/sec
            Reservable BW[3]:        200000        100000  kbits/sec
            Reservable BW[4]:        200000        100000  kbits/sec
            Reservable BW[5]:        200000        100000  kbits/sec
            Reservable BW[6]:        200000        100000  kbits/sec
            Reservable BW[7]:        200000        100000  kbits/sec

          Attribute Flags: 0x00000000
          Attribute Names: 

      Link ID:: 1 (POS0/5/0/1)
          Link IP Address      : 12.5.5.3
          O/G Intf ID          : 17
          Neighbor             : ID 0002.0002.0022.00, IP 12.5.5.2
          TE Metric            : 10
          IGP Metric           : 10
          Physical BW          : 155520 kbits/sec
          BCID                 : RDM 
          Max Reservable BW    : 200000 kbits/sec
          Res Global BW        : 200000 kbits/sec
          Res Sub BW           : 100000 kbits/sec

          Downstream::
                                Global Pool   Sub Pool   
                                -----------   -----------
            Reservable BW[0]:        200000        100000  kbits/sec
            Reservable BW[1]:        200000        100000  kbits/sec
            Reservable BW[2]:        200000        100000  kbits/sec
            Reservable BW[3]:        200000        100000  kbits/sec
            Reservable BW[4]:        200000        100000  kbits/sec
            Reservable BW[5]:        200000        100000  kbits/sec
            Reservable BW[6]:        200000        100000  kbits/sec
            Reservable BW[7]:        200000        100000  kbits/sec

          Attribute Flags: 0x00000000
          Attribute Names: 

  IGP Area[2]:: OSPF 0 area 1
      Flooding Protocol   : OSPF
      IGP System ID       : 103.0.0.3
      MPLS TE Router ID   : 103.0.0.3
      Flooded Links       : 2

      Link ID:: 0 (GigabitEthernet0/2/0/0)
          Link IP Address      : 11.4.4.3
          O/G Intf ID          : 25
          Designated Router    : 11.4.4.3
          TE Metric            : 1
          IGP Metric           : 1
          Physical BW          : 1000000 kbits/sec
          BCID                 : RDM 
          Max Reservable BW    : 200000 kbits/sec
          Res Global BW        : 200000 kbits/sec
          Res Sub BW           : 100000 kbits/sec

          Downstream::
                                Global Pool   Sub Pool   
                                -----------   -----------
            Reservable BW[0]:        200000        100000  kbits/sec
            Reservable BW[1]:        200000        100000  kbits/sec
            Reservable BW[2]:        200000        100000  kbits/sec
            Reservable BW[3]:        200000        100000  kbits/sec
            Reservable BW[4]:        200000        100000  kbits/sec
            Reservable BW[5]:        200000        100000  kbits/sec
            Reservable BW[6]:        200000        100000  kbits/sec
            Reservable BW[7]:        200000        100000  kbits/sec

          Attribute Flags: 0x00000000
          Attribute Names: 

      Link ID:: 1 (POS0/5/0/0)
          Link IP Address      : 12.4.4.3
          O/G Intf ID          : 14
          Neighbor             : ID 102.0.0.2, IP 12.4.4.2
          TE Metric            : 1
          IGP Metric           : 1
          Physical BW          : 155520 kbits/sec
          BCID                 : RDM 
          Max Reservable BW    : 200000 kbits/sec
          Res Global BW        : 200000 kbits/sec
          Res Sub BW           : 100000 kbits/sec

          Downstream::
                                Global Pool   Sub Pool   
                                -----------   -----------
            Reservable BW[0]:        200000        100000  kbits/sec
            Reservable BW[1]:        200000        100000  kbits/sec
            Reservable BW[2]:        200000        100000  kbits/sec
            Reservable BW[3]:        200000        100000  kbits/sec
            Reservable BW[4]:        200000        100000  kbits/sec
            Reservable BW[5]:        200000        100000  kbits/sec
            Reservable BW[6]:        200000        100000  kbits/sec
            Reservable BW[7]:        200000        100000  kbits/sec

          Attribute Flags: 0x00000000
          Attribute Names: 

 

Check that:

  • There's a flooded local LSA for each area TE is running over
  • System-id (IS-IS system id, or OSPF's own router-id)  and TE router-id information is correct for each area
  • The correct links are flooded to each area
  • Link addresses are correct
  • Neighbor information is correct                  
    • For P2P links, this will be the neighbor's system-id and interface IP address
    • For broadcast links, this will be the DR's interface address - which may be the local address if this command is run on the DR.
  • Link data (bandwidths, attributes, etc) is correct (bear in mind thresholds and rounding issues when checking link bandwidths; these are discussed later in this document)

 

 

The local-LSA flooded by TE to the IGP is flooded to the network by  the IGP on TE's behalf. In order to make sure that the IGP has received  the correct local-LSA information, check the IGP's own record of what has been flooded.

 

IS-IS:

 

IS-IS 0 Level-1 MPLS Traffic Engineering advertisements
  System ID: te-ma3
  Router ID: 103.1.1.3
  Link Count: 2
    Link[0]
      Neighbor System ID: te-ma2 (broadcast link)
      Interface IP address: 11.5.5.3
      Neighbor IP Address: 11.5.5.2
      TE Metric: 10
      Physical BW: 1000000 kbits/sec
      Reservable BW global: 200000 kbits/sec
      Reservable BW sub: 100000 kbits/sec
      Global pool BW unreserved: 
        [0]: 200000 kbits/sec, [1]: 200000 kbits/sec
        [2]: 200000 kbits/sec, [3]: 200000 kbits/sec
        [4]: 200000 kbits/sec, [5]: 200000 kbits/sec
        [6]: 200000 kbits/sec, [7]: 200000 kbits/sec
      Sub pool BW unreserved: 
        [0]: 100000 kbits/sec, [1]: 100000 kbits/sec
        [2]: 100000 kbits/sec, [3]: 100000 kbits/sec
        [4]: 100000 kbits/sec, [5]: 100000 kbits/sec
        [6]: 100000 kbits/sec, [7]: 100000 kbits/sec
      Affinity Bits: 0x00000000
    Link[1]
      Neighbor System ID: te-ma2 (P2P link)
      Interface IP address: 12.5.5.3
      Neighbor IP Address: 12.5.5.2
      TE Metric: 10
      Physical BW: 155520 kbits/sec
      Reservable BW global: 200000 kbits/sec
      Reservable BW sub: 100000 kbits/sec
      Global pool BW unreserved: 
        [0]: 200000 kbits/sec, [1]: 200000 kbits/sec
        [2]: 200000 kbits/sec, [3]: 200000 kbits/sec
        [4]: 200000 kbits/sec, [5]: 200000 kbits/sec
        [6]: 200000 kbits/sec, [7]: 200000 kbits/sec
      Sub pool BW unreserved: 
        [0]: 100000 kbits/sec, [1]: 100000 kbits/sec
        [2]: 100000 kbits/sec, [3]: 100000 kbits/sec
        [4]: 100000 kbits/sec, [5]: 100000 kbits/sec
        [6]: 100000 kbits/sec, [7]: 100000 kbits/sec
      Affinity Bits: 0x00000000

 

OSPF:

 

RP/0/0/CPU0:te-ma3#show ospf mpls traffic-eng link     
Wed Jul 28 20:47:19.431 UTC

            OSPF Router with ID (103.0.0.3) (Process ID 0)

  Area 1 has 2 MPLS TE links. Area instance is 20.
    Link is associated with fragment 3. Link instance is 20
      Link connected to Point-to-Point network
      Link ID : 102.0.0.2
      Interface Address : 12.4.4.3
      Neighbor Address : 12.4.4.2
      Admin Metric : TE: 1
      (all bandwidths in bytes/sec)
      Maximum bandwidth : 19440000
      Maximum global pool reservable bandwidth : 25000000
      Maximum sub pool reservable bandwidth    : 12500000
      Number of Priority : 8
      Global pool unreserved BW 
      Priority 0 :             25000000  Priority 1 :             25000000
      Priority 2 :             25000000  Priority 3 :             25000000
      Priority 4 :             25000000  Priority 5 :             25000000
      Priority 6 :             25000000  Priority 7 :             25000000
      Sub pool unreserved BW 
      Priority 0 :             12500000  Priority 1 :             12500000
      Priority 2 :             12500000  Priority 3 :             12500000
      Priority 4 :             12500000  Priority 5 :             12500000
      Priority 6 :             12500000  Priority 7 :             12500000
      Out Interface ID : 14
      Affinity Bit : 0

    Link is associated with fragment 1. Link instance is 20
      Link connected to Broadcast network
      Link ID : 11.4.4.3
      Interface Address : 11.4.4.3
      Admin Metric : TE: 1
      (all bandwidths in bytes/sec)
      Maximum bandwidth : 125000000
      Maximum global pool reservable bandwidth : 25000000
      Maximum sub pool reservable bandwidth    : 12500000
      Number of Priority : 8
      Global pool unreserved BW 
      Priority 0 :             25000000  Priority 1 :             25000000
      Priority 2 :             25000000  Priority 3 :             25000000
      Priority 4 :             25000000  Priority 5 :             25000000
      Priority 6 :             25000000  Priority 7 :             25000000
      Sub pool unreserved BW 
      Priority 0 :             12500000  Priority 1 :             12500000
      Priority 2 :             12500000  Priority 3 :             12500000
      Priority 4 :             12500000  Priority 5 :             12500000
      Priority 6 :             12500000  Priority 7 :             12500000
      Out Interface ID : 25
      Affinity Bit : 0

 

Ensure that the link data given by these commands corresponds to what TE flooded (show mpls traffic-eng link-management advertisements). Any support request for issues in this area will require both TE and IGP showtechs.

 

Topology problems

 

Once TE has flooded its local LSA information to the IGP, the IGP will flood this throughout the network.

 

Does the IGP have the topology complete?

 

Since the IGP is responsible for flooding, we need to ensure that the network topology is complete. There are some differences between the way IS-IS and OSPF flood TE information:

  • OSPF floods the basic router-information (router-id, etc) in LSA fragment 0
  • OSPF then floods one link per fragment.
    The link's fragment id is, in fact, the corresponding interface's SNMP  interface index (this is an XR-specific detail; other implementations  may well do things differently).
  • IS-IS floods as much information as possible in each LSA fragment;  it will only fragment LSAs when there's enough data (or the network MTU  is low enough) that fragmentation is required.

 

When validating the topology in the IGP, check that:

  • The TE router-id is flooded correctly
  • Each link is flooded correctly, with the correct                  
    • local IP address
    • neighbor address
    • link attributes
    • bandwidth information
  • Any required pseudonodes are present for broadcast links

 

These checks need to be done in each IGP-area running TE. It is also necessary to check that the data for each router is correct, on each router. Yes, that's a lot of checking! No matter which IGP you're using, it's very important that the topology is the same on all routers.

 

If topology changes made on one router aren't getting flooded throughout the network (i.e. if discrepancies exist), this probably indicates a general IGP flooding problem.

 

If information for a particular link or router is wrong or missing, but is consistent throughout the network, then there's probably a flooding problem on the originating router; consult the flooding section of this page to debug further on that router.

IS-IS

RP/0/0/CPU0:te-ma1#show isis database verbose
Thu Jul 29 21:08:56.884 UTC

IS-IS 0 (Level-1) Link State Database
LSPID                 LSP Seq Num  LSP Checksum  LSP Holdtime  ATT/P/OL
te-ma1.00-00        * 0x00000029   0x0670        1189            0/0/0
  Area Address: 49
  NLPID:        0xcc
  Hostname:     te-ma1
  IP Address:   101.1.1.1
  Router ID:    101.1.1.1
  Metric: 10         IS-Extended te-ma2.03
    Affinity: 0x00000000
    Interface IP Address: 11.1.1.1
    Neighbor IP Address: 11.1.1.2
    Physical BW: 1000000 kbits/sec
    Reservable Global pool BW: 200000 kbits/sec
    Global Pool BW Unreserved: 
      [0]: 200000   kbits/sec          [1]: 200000   kbits/sec
      [2]: 200000   kbits/sec          [3]: 200000   kbits/sec
      [4]: 200000   kbits/sec          [5]: 200000   kbits/sec
      [6]: 200000   kbits/sec          [7]: 200000   kbits/sec
    Reservable Sub pool BW: 100000 kbits/sec
    Sub pool BW Unreserved: 
      [0]: 100000   kbits/sec          [1]: 100000   kbits/sec
      [2]: 100000   kbits/sec          [3]: 100000   kbits/sec
      [4]: 100000   kbits/sec          [5]: 100000   kbits/sec
      [6]: 100000   kbits/sec          [7]: 100000   kbits/sec
  Metric: 10         IS-Extended te-ma2.00
    Affinity: 0x00000000
    Interface IP Address: 12.1.1.1
    Neighbor IP Address: 12.1.1.2
    Physical BW: 155520 kbits/sec
    Reservable Global pool BW: 200000 kbits/sec
    Global Pool BW Unreserved: 
      [0]: 200000   kbits/sec          [1]: 200000   kbits/sec
      [2]: 200000   kbits/sec          [3]: 200000   kbits/sec
      [4]: 200000   kbits/sec          [5]: 200000   kbits/sec
      [6]: 200000   kbits/sec          [7]: 200000   kbits/sec
    Reservable Sub pool BW: 100000 kbits/sec
    Sub pool BW Unreserved: 
      [0]: 100000   kbits/sec          [1]: 100000   kbits/sec
      [2]: 100000   kbits/sec          [3]: 100000   kbits/sec
      [4]: 100000   kbits/sec          [5]: 100000   kbits/sec
      [6]: 100000   kbits/sec          [7]: 100000   kbits/sec
  Metric: 10         IP-Extended 11.1.1.0/24
  Metric: 10         IP-Extended 12.1.1.0/24
  Metric: 0          IP-Extended 101.1.1.1/32
te-ma2.00-00          0x00000025   0xd480        1010            0/0/0
  Area Address: 49
  NLPID:        0xcc
  Hostname:     te-ma2
  IP Address:   102.1.1.2
  Router ID:    102.1.1.2
  Metric: 10         IS-Extended te-ma2.01
    Affinity: 0x00000000
    Interface IP Address: 11.5.5.2
    Neighbor IP Address: 11.5.5.2
    Physical BW: 1000000 kbits/sec
    Reservable Global pool BW: 200000 kbits/sec
    Global Pool BW Unreserved: 
      [0]: 200000   kbits/sec          [1]: 200000   kbits/sec
      [2]: 200000   kbits/sec          [3]: 200000   kbits/sec
      [4]: 200000   kbits/sec          [5]: 200000   kbits/sec
      [6]: 200000   kbits/sec          [7]: 200000   kbits/sec
    Reservable Sub pool BW: 100000 kbits/sec
    Sub pool BW Unreserved: 
      [0]: 100000   kbits/sec          [1]: 100000   kbits/sec
      [2]: 100000   kbits/sec          [3]: 100000   kbits/sec
      [4]: 100000   kbits/sec          [5]: 100000   kbits/sec
      [6]: 100000   kbits/sec          [7]: 100000   kbits/sec
  Metric: 10         IS-Extended te-ma2.03
    Affinity: 0x00000000
    Interface IP Address: 11.1.1.2
    Neighbor IP Address: 11.1.1.2
    Physical BW: 1000000 kbits/sec
    Reservable Global pool BW: 200000 kbits/sec
    Global Pool BW Unreserved: 
      [0]: 200000   kbits/sec          [1]: 200000   kbits/sec
      [2]: 200000   kbits/sec          [3]: 200000   kbits/sec
      [4]: 200000   kbits/sec          [5]: 200000   kbits/sec
      [6]: 200000   kbits/sec          [7]: 200000   kbits/sec
    Reservable Sub pool BW: 100000 kbits/sec
    Sub pool BW Unreserved: 
      [0]: 100000   kbits/sec          [1]: 100000   kbits/sec
      [2]: 100000   kbits/sec          [3]: 100000   kbits/sec
      [4]: 100000   kbits/sec          [5]: 100000   kbits/sec
      [6]: 100000   kbits/sec          [7]: 100000   kbits/sec
  Metric: 10         IS-Extended te-ma3.00
    Affinity: 0x00000000
    Interface IP Address: 12.5.5.2
    Neighbor IP Address: 12.5.5.3
    Physical BW: 155520 kbits/sec
    Reservable Global pool BW: 200000 kbits/sec
    Global Pool BW Unreserved: 
      [0]: 200000   kbits/sec          [1]: 200000   kbits/sec
      [2]: 200000   kbits/sec          [3]: 200000   kbits/sec
      [4]: 200000   kbits/sec          [5]: 200000   kbits/sec
      [6]: 200000   kbits/sec          [7]: 200000   kbits/sec
    Reservable Sub pool BW: 100000 kbits/sec
    Sub pool BW Unreserved: 
      [0]: 100000   kbits/sec          [1]: 100000   kbits/sec
      [2]: 100000   kbits/sec          [3]: 100000   kbits/sec
      [4]: 100000   kbits/sec          [5]: 100000   kbits/sec
      [6]: 100000   kbits/sec          [7]: 100000   kbits/sec
  Metric: 10         IS-Extended te-ma1.00
    Affinity: 0x00000000
    Interface IP Address: 12.1.1.2
    Neighbor IP Address: 12.1.1.1
    Physical BW: 155520 kbits/sec
    Reservable Global pool BW: 200000 kbits/sec
    Global Pool BW Unreserved: 
      [0]: 200000   kbits/sec          [1]: 200000   kbits/sec
      [2]: 200000   kbits/sec          [3]: 200000   kbits/sec
      [4]: 200000   kbits/sec          [5]: 200000   kbits/sec
      [6]: 200000   kbits/sec          [7]: 200000   kbits/sec
    Reservable Sub pool BW: 100000 kbits/sec
    Sub pool BW Unreserved: 
      [0]: 100000   kbits/sec          [1]: 100000   kbits/sec
      [2]: 100000   kbits/sec          [3]: 100000   kbits/sec
      [4]: 100000   kbits/sec          [5]: 100000   kbits/sec
      [6]: 100000   kbits/sec          [7]: 100000   kbits/sec
  Metric: 10         IP-Extended 11.1.1.0/24
  Metric: 10         IP-Extended 11.5.5.0/24
  Metric: 10         IP-Extended 12.1.1.0/24
  Metric: 10         IP-Extended 12.5.5.0/24
  Metric: 0          IP-Extended 102.1.1.2/32
te-ma2.01-00          0x00000019   0xe878        1164            0/0/0
  Metric: 0          IS-Extended te-ma2.00
  Metric: 0          IS-Extended te-ma3.00
te-ma2.03-00          0x00000004   0x0e4b        1028            0/0/0
  Metric: 0          IS-Extended te-ma2.00
  Metric: 0          IS-Extended te-ma1.00
te-ma3.00-00          0x00000025   0xfb59        1187            0/0/0
  Area Address: 49
  NLPID:        0xcc
  Hostname:     te-ma3
  IP Address:   103.1.1.3
  Router ID:    103.1.1.3
  Metric: 10         IS-Extended te-ma2.01
    Affinity: 0x00000000
    Interface IP Address: 11.5.5.3
    Neighbor IP Address: 11.5.5.2
    Physical BW: 1000000 kbits/sec
    Reservable Global pool BW: 200000 kbits/sec
    Global Pool BW Unreserved: 
      [0]: 200000   kbits/sec          [1]: 200000   kbits/sec
      [2]: 200000   kbits/sec          [3]: 200000   kbits/sec
      [4]: 200000   kbits/sec          [5]: 200000   kbits/sec
      [6]: 200000   kbits/sec          [7]: 200000   kbits/sec
    Reservable Sub pool BW: 100000 kbits/sec
    Sub pool BW Unreserved: 
      [0]: 100000   kbits/sec          [1]: 100000   kbits/sec
      [2]: 100000   kbits/sec          [3]: 100000   kbits/sec
      [4]: 100000   kbits/sec          [5]: 100000   kbits/sec
      [6]: 100000   kbits/sec          [7]: 100000   kbits/sec
  Metric: 10         IS-Extended te-ma2.00
    Affinity: 0x00000000
    Interface IP Address: 12.5.5.3
    Neighbor IP Address: 12.5.5.2
    Physical BW: 155520 kbits/sec
    Reservable Global pool BW: 200000 kbits/sec
    Global Pool BW Unreserved: 
      [0]: 200000   kbits/sec          [1]: 200000   kbits/sec
      [2]: 200000   kbits/sec          [3]: 200000   kbits/sec
      [4]: 200000   kbits/sec          [5]: 200000   kbits/sec
      [6]: 200000   kbits/sec          [7]: 200000   kbits/sec
    Reservable Sub pool BW: 100000 kbits/sec
    Sub pool BW Unreserved: 
      [0]: 100000   kbits/sec          [1]: 100000   kbits/sec
      [2]: 100000   kbits/sec          [3]: 100000   kbits/sec
      [4]: 100000   kbits/sec          [5]: 100000   kbits/sec
      [6]: 100000   kbits/sec          [7]: 100000   kbits/sec
  Metric: 10         IP-Extended 11.5.5.0/24
  Metric: 10         IP-Extended 12.5.5.0/24
  Metric: 0          IP-Extended 103.1.1.3/32
te-ma3.01-00          0x00000019   0x0000        0 (1190)        0/0/0

 Total Level-1 LSP count: 6     Local Level-1 LSP count: 1

 

The verbose option is necessary here to have the TE data displayed in the command output.

 

Note that the pseudonode LSAs for LAN circuits are also visible in the database, as well as the router node data generated by TE. The pseudonode LSAs are generated by IS-IS without any involvement from TE - if they aren't present when they should be, this is probably an IS-IS issue rather than a TE one.

OSPF

RP/0/0/CPU0:te-ma1#show ospf database opaque-area 
Fri Jul 30 19:32:36.698 UTC


            OSPF Router with ID (101.0.0.1) (Process ID 0)

                Type-10 Opaque Link Area Link States (Area 1)

  LS age: 1895
  Options: (No TOS-capability, DC)
  LS Type: Opaque Area Link
  Link State ID: 1.0.0.0
  Opaque Type: 1
  Opaque ID: 0
  Advertising Router: 101.0.0.1
  LS Seq Number: 8000002f
  Checksum: 0x3106
  Length: 28

    MPLS TE router ID : 101.0.0.1

    Number of Links : 0

  LS age: 308
  Options: (No TOS-capability, DC)
  LS Type: Opaque Area Link
  Link State ID: 1.0.0.0
  Opaque Type: 1
  Opaque ID: 0
  Advertising Router: 102.0.0.2
  LS Seq Number: 80000030
  Checksum: 0x3101
  Length: 28

    MPLS TE router ID : 102.0.0.2

    Number of Links : 0

  LS age: 655
  Options: (No TOS-capability, DC)
  LS Type: Opaque Area Link
  Link State ID: 1.0.0.0
  Opaque Type: 1
  Opaque ID: 0
  Advertising Router: 103.0.0.3
  LS Seq Number: 80000030
  Checksum: 0x33fa
  Length: 28

    MPLS TE router ID : 103.0.0.3

    Number of Links : 0

  LS age: 308
  Options: (No TOS-capability, DC)
  LS Type: Opaque Area Link
  Link State ID: 1.0.0.14
  Opaque Type: 1
  Opaque ID: 14
  Advertising Router: 102.0.0.2
  LS Seq Number: 80000031
  Checksum: 0xca52
  Length: 176

    Link connected to Point-to-Point network
      Link ID : 101.0.0.1
      (all bandwidths in bytes/sec)
      Interface Address : 12.0.0.2
      Neighbor Address : 12.0.0.1
      Admin Metric : 1
      Maximum bandwidth : 19440000
      Maximum reservable bandwidth global: 25000000
      Number of Priority : 8
      Priority 0 :             25000000  Priority 1 :             25000000
      Priority 2 :             25000000  Priority 3 :             25000000
      Priority 4 :             25000000  Priority 5 :             25000000
      Priority 6 :             25000000  Priority 7 :             25000000
      Affinity Bit : 0
      Maximum reservable sub-pool bandwidth : 12500000
      Number of Priority : 8
      Priority 0 :             12500000  Priority 1 :             12500000
      Priority 2 :             12500000  Priority 3 :             12500000
      Priority 4 :             12500000  Priority 5 :             12500000
      Priority 6 :             12500000  Priority 7 :             12500000
      IGP Metric : 1

    Number of Links : 1

  LS age: 655
  Options: (No TOS-capability, DC)
  LS Type: Opaque Area Link
  Link State ID: 1.0.0.14
  Opaque Type: 1
  Opaque ID: 14
  Advertising Router: 103.0.0.3
  LS Seq Number: 80000031
  Checksum: 0x33d3
  Length: 176

    Link connected to Point-to-Point network
      Link ID : 102.0.0.2
      (all bandwidths in bytes/sec)
      Interface Address : 12.4.4.3
      Neighbor Address : 12.4.4.2
      Admin Metric : 1
      Maximum bandwidth : 19440000
      Maximum reservable bandwidth global: 25000000
      Number of Priority : 8
      Priority 0 :             25000000  Priority 1 :             25000000
      Priority 2 :             25000000  Priority 3 :             25000000
      Priority 4 :             25000000  Priority 5 :             25000000
      Priority 6 :             25000000  Priority 7 :             25000000
      Affinity Bit : 0
      Maximum reservable sub-pool bandwidth : 12500000
      Number of Priority : 8
      Priority 0 :             12500000  Priority 1 :             12500000
      Priority 2 :             12500000  Priority 3 :             12500000
      Priority 4 :             12500000  Priority 5 :             12500000
      Priority 6 :             12500000  Priority 7 :             12500000
      IGP Metric : 1

    Number of Links : 1

  LS age: 888
  Options: (No TOS-capability, DC)
  LS Type: Opaque Area Link
  Link State ID: 1.0.0.15
  Opaque Type: 1
  Opaque ID: 15
  Advertising Router: 101.0.0.1
  LS Seq Number: 8000002a
  Checksum: 0xf14
  Length: 176

    Link connected to Point-to-Point network
      Link ID : 102.0.0.2
      (all bandwidths in bytes/sec)
      Interface Address : 12.0.0.1
      Neighbor Address : 12.0.0.2
      Admin Metric : 1
      Maximum bandwidth : 19440000
      Maximum reservable bandwidth global: 25000000
      Number of Priority : 8
      Priority 0 :             25000000  Priority 1 :             25000000
      Priority 2 :             25000000  Priority 3 :             25000000
      Priority 4 :             25000000  Priority 5 :             25000000
      Priority 6 :             25000000  Priority 7 :             25000000
      Affinity Bit : 0
      Maximum reservable sub-pool bandwidth : 12500000
      Number of Priority : 8
      Priority 0 :             12500000  Priority 1 :             12500000
      Priority 2 :             12500000  Priority 3 :             12500000
      Priority 4 :             12500000  Priority 5 :             12500000
      Priority 6 :             12500000  Priority 7 :             12500000
      IGP Metric : 1

    Number of Links : 1

  LS age: 1308
  Options: (No TOS-capability, DC)
  LS Type: Opaque Area Link
  Link State ID: 1.0.0.20
  Opaque Type: 1
  Opaque ID: 20
  Advertising Router: 102.0.0.2
  LS Seq Number: 80000037
  Checksum: 0x2bcf
  Length: 176

    Link connected to Point-to-Point network
      Link ID : 103.0.0.3
      (all bandwidths in bytes/sec)
      Interface Address : 12.4.4.2
      Neighbor Address : 12.4.4.3
      Admin Metric : 1
      Maximum bandwidth : 19440000
      Maximum reservable bandwidth global: 25000000
      Number of Priority : 8
      Priority 0 :             25000000  Priority 1 :             25000000
      Priority 2 :             25000000  Priority 3 :             25000000
      Priority 4 :             25000000  Priority 5 :             25000000
      Priority 6 :             25000000  Priority 7 :             25000000
      Affinity Bit : 0
      Maximum reservable sub-pool bandwidth : 12500000
      Number of Priority : 8
      Priority 0 :             12500000  Priority 1 :             12500000
      Priority 2 :             12500000  Priority 3 :             12500000
      Priority 4 :             12500000  Priority 5 :             12500000
      Priority 6 :             12500000  Priority 7 :             12500000
      IGP Metric : 1

    Number of Links : 1

  LS age: 308
  Options: (No TOS-capability, DC)
  LS Type: Opaque Area Link
  Link State ID: 1.0.0.25
  Opaque Type: 1
  Opaque ID: 25
  Advertising Router: 102.0.0.2
  LS Seq Number: 80000031
  Checksum: 0x4e64
  Length: 168

    Link connected to Broadcast network
      Link ID : 11.0.0.2
      (all bandwidths in bytes/sec)
      Interface Address : 11.0.0.2
      Admin Metric : 1
      Maximum bandwidth : 125000000
      Maximum reservable bandwidth global: 25000000
      Number of Priority : 8
      Priority 0 :             25000000  Priority 1 :             25000000
      Priority 2 :             25000000  Priority 3 :             25000000
      Priority 4 :             25000000  Priority 5 :             25000000
      Priority 6 :             25000000  Priority 7 :             25000000
      Affinity Bit : 0
      Maximum reservable sub-pool bandwidth : 12500000
      Number of Priority : 8
      Priority 0 :             12500000  Priority 1 :             12500000
      Priority 2 :             12500000  Priority 3 :             12500000
      Priority 4 :             12500000  Priority 5 :             12500000
      Priority 6 :             12500000  Priority 7 :             12500000
      IGP Metric : 1

    Number of Links : 1

  LS age: 655
  Options: (No TOS-capability, DC)
  LS Type: Opaque Area Link
  Link State ID: 1.0.0.25
  Opaque Type: 1
  Opaque ID: 25
  Advertising Router: 103.0.0.3
  LS Seq Number: 80000031
  Checksum: 0xfca1
  Length: 168

    Link connected to Broadcast network
      Link ID : 11.4.4.3
      (all bandwidths in bytes/sec)
      Interface Address : 11.4.4.3
      Admin Metric : 1
      Maximum bandwidth : 125000000
      Maximum reservable bandwidth global: 25000000
      Number of Priority : 8
      Priority 0 :             25000000  Priority 1 :             25000000
      Priority 2 :             25000000  Priority 3 :             25000000
      Priority 4 :             25000000  Priority 5 :             25000000
      Priority 6 :             25000000  Priority 7 :             25000000
      Affinity Bit : 0
      Maximum reservable sub-pool bandwidth : 12500000
      Number of Priority : 8
      Priority 0 :             12500000  Priority 1 :             12500000
      Priority 2 :             12500000  Priority 3 :             12500000
      Priority 4 :             12500000  Priority 5 :             12500000
      Priority 6 :             12500000  Priority 7 :             12500000
      IGP Metric : 1

    Number of Links : 1

  LS age: 888
  Options: (No TOS-capability, DC)
  LS Type: Opaque Area Link
  Link State ID: 1.0.0.26
  Opaque Type: 1
  Opaque ID: 26
  Advertising Router: 101.0.0.1
  LS Seq Number: 8000002a
  Checksum: 0x4378
  Length: 168

    Link connected to Broadcast network
      Link ID : 11.0.0.2
      (all bandwidths in bytes/sec)
      Interface Address : 11.0.0.1
      Admin Metric : 1
      Maximum bandwidth : 125000000
      Maximum reservable bandwidth global: 25000000
      Number of Priority : 8
      Priority 0 :             25000000  Priority 1 :             25000000
      Priority 2 :             25000000  Priority 3 :             25000000
      Priority 4 :             25000000  Priority 5 :             25000000
      Priority 6 :             25000000  Priority 7 :             25000000
      Affinity Bit : 0
      Maximum reservable sub-pool bandwidth : 12500000
      Number of Priority : 8
      Priority 0 :             12500000  Priority 1 :             12500000
      Priority 2 :             12500000  Priority 3 :             12500000
      Priority 4 :             12500000  Priority 5 :             12500000
      Priority 6 :             12500000  Priority 7 :             12500000
      IGP Metric : 1

    Number of Links : 1

  LS age: 1308
  Options: (No TOS-capability, DC)
  LS Type: Opaque Area Link
  Link State ID: 1.0.0.27
  Opaque Type: 1
  Opaque ID: 27
  Advertising Router: 102.0.0.2
  LS Seq Number: 80000034
  Checksum: 0xd3c8
  Length: 168

    Link connected to Broadcast network
      Link ID : 11.4.4.3
      (all bandwidths in bytes/sec)
      Interface Address : 11.4.4.2
      Admin Metric : 1
      Maximum bandwidth : 125000000
      Maximum reservable bandwidth global: 25000000
      Number of Priority : 8
      Priority 0 :             25000000  Priority 1 :             25000000
      Priority 2 :             25000000  Priority 3 :             25000000
      Priority 4 :             25000000  Priority 5 :             25000000
      Priority 6 :             25000000  Priority 7 :             25000000
      Affinity Bit : 0
      Maximum reservable sub-pool bandwidth : 12500000
      Number of Priority : 8
      Priority 0 :             12500000  Priority 1 :             12500000
      Priority 2 :             12500000  Priority 3 :             12500000
      Priority 4 :             12500000  Priority 5 :             12500000
      Priority 6 :             12500000  Priority 7 :             12500000
      IGP Metric : 1

    Number of Links : 1

 

The pseudonodes for OSPF aren't visible with this show command as they're a different LSA type; use show ospf database network to see them. Again, they're generated by OSPF itself, rather than TE - if they aren't present when they should be, this probably indicates an OSPF issue.

 


 
RP/0/0/CPU0:te-ma1#show ospf database network Fri Jul 30 19:52:10.496 UTC             OSPF Router with ID (101.0.0.1) (Process ID 0)                 Net Link States (Area 1)   Routing Bit Set on this LSA   LS age: 202   Options: (No TOS-capability, DC)   LS Type: Network Links   Link State ID: 11.0.0.2 (address of Designated Router)   Advertising Router: 102.0.0.2   LS Seq Number: 80000033   Checksum: 0x447f   Length: 32   Network Mask: /24         Attached Router: 101.0.0.1         Attached Router: 102.0.0.2   Routing Bit Set on this LSA   LS age: 324   Options: (No TOS-capability, DC)   LS Type: Network Links   Link State ID: 11.4.4.3 (address of Designated Router)   Advertising Router: 103.0.0.3   LS Seq Number: 80000033   Checksum: 0xf8bb   Length: 32   Network Mask: /24         Attached Router: 102.0.0.2         Attached Router: 103.0.0.3

 

Does the TE have the topology complete?

 

show mpls traffic-eng topology produces a lot of output. It's therefore a good idea to use options on it to reduce this where possible, and worth getting to know what the various options do so that you can use whichever one's most appropriate for the information you're trying to find. Note that the examples given in this section cover both  the IS-IS and OSPF topologies used as examples in the previous section.

 

A first look

show mpls traffic-eng topology model-type rdm (or model-type dste, if you've configured DS-TE in the network) and show mpls traffic-eng topology summary give the briefest available summaries of the topology. Both are useful for quick sanity checks.

 

The model-type version of the command gives a simple list of nodes and links. Network pseudonodes are not displayed.

 

RP/0/0/CPU0:te-ma1#show mpls traffic-eng topology model-type rdm 
Fri Jul 30 20:07:50.893 UTC


IGP Id: 0001.0011.0111.00, MPLS TE Id: 101.1.1.1 Router Node  (IS-IS 0 level-1)
  Link[0]:      Intf Address: 11.1.1.1, DR: 0002.0002.0022.03
  Link[1]:      Intf Address: 12.1.1.1, Nbr Intf Address: 12.1.1.2

IGP Id: 0002.0002.0022.00, MPLS TE Id: 102.1.1.2 Router Node  (IS-IS 0 level-1)
  Link[0]:      Intf Address: 11.5.5.2, DR: 0002.0002.0022.01
  Link[1]:      Intf Address: 11.1.1.2, DR: 0002.0002.0022.03
  Link[2]:      Intf Address: 12.5.5.2, Nbr Intf Address: 12.5.5.3
  Link[3]:      Intf Address: 12.1.1.2, Nbr Intf Address: 12.1.1.1
IGP Id: 0003.0003.0003.00, MPLS TE Id: 103.1.1.3 Router Node  (IS-IS 0 level-1)
  Link[0]:      Intf Address: 11.5.5.3, DR: 0002.0002.0022.01
  Link[1]:      Intf Address: 12.5.5.3, Nbr Intf Address: 12.5.5.2
IGP Id: 101.0.0.1, MPLS TE Id: 101.0.0.1 Router Node  (OSPF 0 area 1)
  Link[0]:      Intf Address: 11.0.0.1, DR: 11.0.0.2
  Link[1]:      Intf Address: 12.0.0.1, Nbr Intf Address: 12.0.0.2
IGP Id: 102.0.0.2, MPLS TE Id: 102.0.0.2 Router Node  (OSPF 0 area 1)
  Link[0]:      Intf Address: 12.0.0.2, Nbr Intf Address: 12.0.0.1
  Link[1]:      Intf Address: 12.4.4.2, Nbr Intf Address: 12.4.4.3
  Link[2]:      Intf Address: 11.0.0.2, DR: 11.0.0.2
  Link[3]:      Intf Address: 11.4.4.2, DR: 11.4.4.3
IGP Id: 103.0.0.3, MPLS TE Id: 103.0.0.3 Router Node  (OSPF 0 area 1)
  Link[0]:      Intf Address: 12.4.4.3, Nbr Intf Address: 12.4.4.2
  Link[1]:      Intf Address: 11.4.4.3, DR: 11.4.4.3

 

For each node, we have:

  • The IGP system ID (OSPF router-id or IS-IS system-id)
  • TE router-id
  • The IGP-area that the node is in

 

For each link, we have:

  • The link's local address
  • Neighbor information

 

Note the difference in the way that p2p and broadcast links are displayed:

  • for p2p links, the neighbor's interface address is given
  • for broadcast links:                 
    • for IS-IS, the IS-IS node-id of the network pseudonode is given. The first six bytes of this are the system-id of the generating router (DIS).
    • for OSPF, the DR's interface address is given; on the DR this is the same as the interface address.

 

The summary version of the command doesn't display links, but does display network pseudonodes.

 

RP/0/0/CPU0:te-ma1#show mpls traffic-eng topology summary 
Fri Jul 30 20:09:18.593 UTC
My_System_id: 101.0.0.1 (OSPF 0 area 1)
My_System_id: 0001.0011.0111.00 (IS-IS 0 level-1)
My_BC_Model_Type: RDM 

Signalling error holddown: 10 sec Global Link Generation 51394

IS-IS 0  level 1
  Local System Id:          0001.0011.0111
  TE router ID configured:  101.1.1.1
               in use:      101.1.1.1

    IGP Id: 0001.0011.0111.00, MPLS TE Id: 101.1.1.1 Router Node 
        2 links

    IGP Id: 0002.0002.0022.00, MPLS TE Id: 102.1.1.2 Router Node 
        4 links

    IGP Id: 0003.0003.0003.00, MPLS TE Id: 103.1.1.3 Router Node 
        2 links

    IGP Id: 0002.0002.0022.01, Network Node 
        2 links

    IGP Id: 0002.0002.0022.03, Network Node 
        2 links

    Total: 5 nodes (3 router, 2 network), 12 links

OSPF 0  area 1
  Local System Id:          101.0.0.1
  TE router ID configured:  101.0.0.1
               in use:      101.0.0.1

    IGP Id: 101.0.0.1, MPLS TE Id: 101.0.0.1 Router Node 
        2 links

    IGP Id: 102.0.0.2, MPLS TE Id: 102.0.0.2 Router Node 
        4 links

    IGP Id: 103.0.0.3, MPLS TE Id: 103.0.0.3 Router Node 
        2 links

    IGP Id: 11.0.0.2, Network Node 
        2 links

    IGP Id: 11.4.4.3, Network Node 
        2 links

    Total: 5 nodes (3 router, 2 network), 12 links

Grand Total: 10 nodes (6 router, 4 network)  24 links
RP/0/0/CPU0:te-ma1#

 

These two commands are very useful to check for:

 

  • router nodes that are missing entirely (both)
  • network nodes that are absent (summary command)
  • missing links (model-type command)
  • missing IP addresses (model-type command)

 

If data is found to be missing in the TE topology, then check that the IGP topology is complete. If the IGP topology is complete then we probably have a communication issue between TE and the IGP; in this case both TE and IGP showtechs will be required for any support request. If the information is missing in the IGP topology, keep investigating to find out what's gone wrong.

 

Many issues parts of the topology missing (or the entire topology missing) end up being due to missing config somewhere - so it's worth double-checking this. If the entire topology is missing, also check the output of show mpls traffic-eng igp-areas and ensure that the connections between TE and the IGP are up.

 

Note that each router is seen as a separate node in each IGP-area. This means that if you're running more than one IGP-area over the same routers and links, the topology can rapidly become extremely large. Consider making use of the various filter options available, if appropriate.

IS-IS Overload bit

 

If the OL-bit is set on a node in an IS-IS topology, the router node will be shown in the TE topology like this:

 


 
IGP Id: 0001.0011.0111.00, MPLS TE Id: 101.1.1.1 Router Node (NO SPF) (IS-IS 0 level-1)

Note the NO SPF designation for the node. TE will exclude a node with the OL bit set from its cSPF calculations unless configured to ignore it.

 

 

The brief option to the TE topology show command displays all nodes and links, but omits most of the bandwidth data.

 

RP/0/0/CPU0:te-ma1#show mpls traffic-eng topology brief 
Tue Aug  3 18:12:11.095 UTC
My_System_id: 101.0.0.1 (OSPF 0 area 1)
My_System_id: 0001.0011.0111.00 (IS-IS 0 level-1)
My_BC_Model_Type: RDM 

Signalling error holddown: 10 sec Global Link Generation 194011

IGP Id: 0001.0011.0111.00, MPLS TE Id: 101.1.1.1 Router Node  (IS-IS 0 level-1)

  Link[0]:Broadcast, DR:0002.0002.0022.03, Nbr Node Id:18, gen:194000
      Frag Id:0, Intf Address:11.1.1.1, Intf Id:0
      Nbr Intf Address:11.1.1.2, Nbr Intf Id:0
      TE Metric:10, IGP Metric:10, Attribute Flags:0x48 
      Attribute Names: blue yellow 
      SRLGs: 5 
      Switching Capability:None, Encoding:unassigned
      BC Model ID:RDM
      Physical BW:1000000 (kbps), Max Reservable BW Global:200000 (kbps)
      Max Reservable BW Sub:100000 (kbps)

  Link[1]:Point-to-Point, Nbr IGP Id:0002.0002.0022.00, Nbr Node Id:13, gen:194001
      Frag Id:0, Intf Address:12.1.1.1, Intf Id:0
      Nbr Intf Address:12.1.1.2, Nbr Intf Id:0
      TE Metric:10, IGP Metric:10, Attribute Flags:0x42 
      Attribute Names: red yellow 
      SRLGs: 3, 20 
      Switching Capability:None, Encoding:unassigned
      BC Model ID:RDM
      Physical BW:155520 (kbps), Max Reservable BW Global:200000 (kbps)
      Max Reservable BW Sub:100000 (kbps)

IGP Id: 0002.0002.0022.00, MPLS TE Id: 102.1.1.2 Router Node  (IS-IS 0 level-1)

  Link[0]:Broadcast, DR:0002.0002.0022.01, Nbr Node Id:14, gen:194002
      Frag Id:0, Intf Address:11.5.5.2, Intf Id:0
      Nbr Intf Address:11.5.5.2, Nbr Intf Id:0
      TE Metric:10, IGP Metric:10, Attribute Flags:0x48 
      Attribute Names: blue yellow 
      Switching Capability:None, Encoding:unassigned
      BC Model ID:RDM
      Physical BW:1000000 (kbps), Max Reservable BW Global:200000 (kbps)
      Max Reservable BW Sub:100000 (kbps)

  Link[1]:Broadcast, DR:0002.0002.0022.03, Nbr Node Id:18, gen:194003
      Frag Id:0, Intf Address:11.1.1.2, Intf Id:0
      Nbr Intf Address:11.1.1.2, Nbr Intf Id:0
      TE Metric:10, IGP Metric:10, Attribute Flags:0x48 
      Attribute Names: blue yellow 
      Switching Capability:None, Encoding:unassigned
      BC Model ID:RDM
      Physical BW:1000000 (kbps), Max Reservable BW Global:200000 (kbps)
      Max Reservable BW Sub:100000 (kbps)

  Link[2]:Point-to-Point, Nbr IGP Id:0003.0003.0003.00, Nbr Node Id:15, gen:194004
      Frag Id:0, Intf Address:12.5.5.2, Intf Id:0
      Nbr Intf Address:12.5.5.3, Nbr Intf Id:0
      TE Metric:10, IGP Metric:10, Attribute Flags:0x2 
      Attribute Names: red 
      Switching Capability:None, Encoding:unassigned
      BC Model ID:RDM
      Physical BW:155520 (kbps), Max Reservable BW Global:200000 (kbps)
      Max Reservable BW Sub:100000 (kbps)

  Link[3]:Point-to-Point, Nbr IGP Id:0001.0011.0111.00, Nbr Node Id:12, gen:194005
      Frag Id:0, Intf Address:12.1.1.2, Intf Id:0
      Nbr Intf Address:12.1.1.1, Nbr Intf Id:0
      TE Metric:10, IGP Metric:10, Attribute Flags:0x42 
      Attribute Names: red yellow 
      Switching Capability:None, Encoding:unassigned
      BC Model ID:RDM
      Physical BW:155520 (kbps), Max Reservable BW Global:200000 (kbps)
      Max Reservable BW Sub:100000 (kbps)

IGP Id: 0003.0003.0003.00, MPLS TE Id: 103.1.1.3 Router Node  (IS-IS 0 level-1)

  Link[0]:Broadcast, DR:0002.0002.0022.01, Nbr Node Id:14, gen:194008
      Frag Id:0, Intf Address:11.5.5.3, Intf Id:0
      Nbr Intf Address:11.5.5.2, Nbr Intf Id:0
      TE Metric:10, IGP Metric:10, Attribute Flags:0x48 
      Attribute Names: blue yellow 
      Switching Capability:None, Encoding:unassigned
      BC Model ID:RDM
      Physical BW:1000000 (kbps), Max Reservable BW Global:200000 (kbps)
      Max Reservable BW Sub:100000 (kbps)

  Link[1]:Point-to-Point, Nbr IGP Id:0002.0002.0022.00, Nbr Node Id:13, gen:194009
      Frag Id:0, Intf Address:12.5.5.3, Intf Id:0
      Nbr Intf Address:12.5.5.2, Nbr Intf Id:0
      TE Metric:10, IGP Metric:10, Attribute Flags:0x42 
      Attribute Names: red yellow 
      Switching Capability:None, Encoding:unassigned
      BC Model ID:RDM
      Physical BW:155520 (kbps), Max Reservable BW Global:200000 (kbps)
      Max Reservable BW Sub:100000 (kbps)

IGP Id: 0002.0002.0022.01, Network Node  (IS-IS 0 level-1)

  Link[0]:Broadcast, DR:0002.0002.0022.00, Nbr Node Id:13, gen:194006
      Physical BW:0 (kbps), Max Reservable BW Global:0 (kbps)
      Max Reservable BW Sub:0 (kbps)

  Link[1]:Broadcast, DR:0003.0003.0003.00, Nbr Node Id:15, gen:194007
      Physical BW:0 (kbps), Max Reservable BW Global:0 (kbps)
      Max Reservable BW Sub:0 (kbps)

IGP Id: 0002.0002.0022.03, Network Node  (IS-IS 0 level-1)

  Link[0]:Broadcast, DR:0002.0002.0022.00, Nbr Node Id:13, gen:194010
      Physical BW:0 (kbps), Max Reservable BW Global:0 (kbps)
      Max Reservable BW Sub:0 (kbps)

  Link[1]:Broadcast, DR:0001.0011.0111.00, Nbr Node Id:12, gen:194011
      Physical BW:0 (kbps), Max Reservable BW Global:0 (kbps)
      Max Reservable BW Sub:0 (kbps)

IGP Id: 101.0.0.1, MPLS TE Id: 101.0.0.1 Router Node  (OSPF 0 area 1)

  Link[0]:Broadcast, DR:11.0.0.2, Nbr Node Id:1, gen:193992
      Frag Id:26, Intf Address:11.0.0.1, Intf Id:0
      Nbr Intf Address:0.0.0.0, Nbr Intf Id:0
      TE Metric:1, IGP Metric:1, Attribute Flags:0x48 
      Attribute Names: blue yellow 
      SRLGs: 5 
      Switching Capability:None, Encoding:unassigned
      BC Model ID:RDM
      Physical BW:1000000 (kbps), Max Reservable BW Global:200000 (kbps)
      Max Reservable BW Sub:100000 (kbps)

  Link[1]:Point-to-Point, Nbr IGP Id:102.0.0.2, Nbr Node Id:5, gen:193993
      Frag Id:15, Intf Address:12.0.0.1, Intf Id:0
      Nbr Intf Address:12.0.0.2, Nbr Intf Id:0
      TE Metric:1, IGP Metric:1, Attribute Flags:0x42 
      Attribute Names: red yellow 
      SRLGs: 20, 30      Switching Capability:None, Encoding:unassigned
      BC Model ID:RDM
      Physical BW:155520 (kbps), Max Reservable BW Global:200000 (kbps)
      Max Reservable BW Sub:100000 (kbps)

IGP Id: 102.0.0.2, MPLS TE Id: 102.0.0.2 Router Node  (OSPF 0 area 1)

  Link[0]:Point-to-Point, Nbr IGP Id:101.0.0.1, Nbr Node Id:4, gen:193994
      Frag Id:14, Intf Address:12.0.0.2, Intf Id:0
      Nbr Intf Address:12.0.0.1, Nbr Intf Id:0
      TE Metric:1, IGP Metric:1, Attribute Flags:0x42
      Attribute Names: red yellow 
      Switching Capability:None, Encoding:unassigned
      BC Model ID:RDM
      Physical BW:155520 (kbps), Max Reservable BW Global:200000 (kbps)
      Max Reservable BW Sub:100000 (kbps)

  Link[1]:Point-to-Point, Nbr IGP Id:103.0.0.3, Nbr Node Id:6, gen:193995
      Frag Id:20, Intf Address:12.4.4.2, Intf Id:0
      Nbr Intf Address:12.4.4.3, Nbr Intf Id:0
      TE Metric:1, IGP Metric:1, Attribute Flags:0x2
      Attribute Names: red 
      Switching Capability:None, Encoding:unassigned
      BC Model ID:RDM
      Physical BW:155520 (kbps), Max Reservable BW Global:200000 (kbps)
      Max Reservable BW Sub:100000 (kbps)

  Link[2]:Broadcast, DR:11.0.0.2, Nbr Node Id:1, gen:193996
      Frag Id:25, Intf Address:11.0.0.2, Intf Id:0
      Nbr Intf Address:0.0.0.0, Nbr Intf Id:0
      TE Metric:1, IGP Metric:1, Attribute Flags:0x48
      Attribute Names: blue yellow 
      Switching Capability:None, Encoding:unassigned
      BC Model ID:RDM
      Physical BW:1000000 (kbps), Max Reservable BW Global:200000 (kbps)
      Max Reservable BW Sub:100000 (kbps)

  Link[3]:Broadcast, DR:11.4.4.3, Nbr Node Id:3, gen:193997
      Frag Id:27, Intf Address:11.4.4.2, Intf Id:0
      Nbr Intf Address:0.0.0.0, Nbr Intf Id:0
      TE Metric:1, IGP Metric:1, Attribute Flags:0x48
      Attribute Names: blue yellow 
      Switching Capability:None, Encoding:unassigned
      BC Model ID:RDM
      Physical BW:1000000 (kbps), Max Reservable BW Global:200000 (kbps)
      Max Reservable BW Sub:100000 (kbps)

IGP Id: 103.0.0.3, MPLS TE Id: 103.0.0.3 Router Node  (OSPF 0 area 1)

  Link[0]:Point-to-Point, Nbr IGP Id:102.0.0.2, Nbr Node Id:5, gen:193998
      Frag Id:14, Intf Address:12.4.4.3, Intf Id:0
      Nbr Intf Address:12.4.4.2, Nbr Intf Id:0
      TE Metric:1, IGP Metric:1, Attribute Flags:0x42
      Attribute Names: red yellow 
      Switching Capability:None, Encoding:unassigned
      BC Model ID:RDM
      Physical BW:155520 (kbps), Max Reservable BW Global:200000 (kbps)
      Max Reservable BW Sub:100000 (kbps)

  Link[1]:Broadcast, DR:11.4.4.3, Nbr Node Id:3, gen:193999
      Frag Id:25, Intf Address:11.4.4.3, Intf Id:0
      Nbr Intf Address:0.0.0.0, Nbr Intf Id:0
      TE Metric:1, IGP Metric:1, Attribute Flags:0x48
      Attribute Names: blue yellow 
      Switching Capability:None, Encoding:unassigned
      BC Model ID:RDM
      Physical BW:1000000 (kbps), Max Reservable BW Global:200000 (kbps)
      Max Reservable BW Sub:100000 (kbps)

IGP Id: 11.0.0.2, Network Node  (OSPF 0 area 1)

  Link[0]:Broadcast, DR:101.0.0.1, Nbr Node Id:4, gen:193988
      Physical BW:0 (kbps), Max Reservable BW Global:0 (kbps)
      Max Reservable BW Sub:0 (kbps)

  Link[1]:Broadcast, DR:102.0.0.2, Nbr Node Id:5, gen:193989
      Physical BW:0 (kbps), Max Reservable BW Global:0 (kbps)
      Max Reservable BW Sub:0 (kbps)

IGP Id: 11.4.4.3, Network Node  (OSPF 0 area 1)

  Link[0]:Broadcast, DR:102.0.0.2, Nbr Node Id:5, gen:193990
      Physical BW:0 (kbps), Max Reservable BW Global:0 (kbps)
      Max Reservable BW Sub:0 (kbps)

  Link[1]:Broadcast, DR:103.0.0.3, Nbr Node Id:6, gen:193991
      Physical BW:0 (kbps), Max Reservable BW Global:0 (kbps)
      Max Reservable BW Sub:0 (kbps)

 

Node information supplied is as for the model-type version of the command above. Ensure that expected nodes exist.

 

For suspect links in the topology, check:

  • The type (broadcast or p2p) is correct
  • The neighbor IGP-id (for p2p links) or DR (for broadcast) is correct
  • The neighbor node-id is not -1 (more on this below)
  • The fragment ID is correct (and consistent with what you see in the IGP topology database)
  • The local interface address is correct
  • The neighbor address is correct (0.0.0.0 is expected for broadcast links)
  • In the case of unnumbered links, the local and neighbor interface IDs are correct
  • The TE and IGP metrics are correct
  • The link attributes (if any) are correct, and are resolved to the correct names if an affinity-map is configured
  • The link SRLGs (if any) are correct

 

For broadcast links, check that the network node for the LAN exists and that the links to and from it for all routers on the LAN are correct.

 

If link data is wrong, check the IGP topology; if it's OK there, check the flooding on the originating router as described earlier in this document.

 

Neighbor node-id

 

The neighbor node-id is an internal mechanism used by TE. Its purpose is to help TE construct the topology and to run cSPF calculations more  quickly by reducing the time it takes to find the next node in the topology when following a link. The node-ids are assigned by TE as topology nodes are learned, so they aren't predictable or deterministic. You don't need  to worry about this most of the time, but there's one exception.

 

If you see Nbr Node Id:-1, this indicates a link that points to a node that TE doesn't know about or can't find in its topology. It's possible to see this as a transient condition when the topology is being built, but this is rare. If it persists, it indicates an error condition. If you see it:

  • Check carefully to see if the node which should be on the other end of this link is, in fact, absent from the topology
  • If it's missing, investigate why (check the IGP topology, and the flooding for that node).
  • Frequently, the cause is simply that the neighbor on the link in question isn't running TE (which is in turn often due to config error).

 

SRLGs

Link SRLGs are easily examined with the show mpls traffic-eng topology srlg command, which gives one line per link/SRLG - much easier than wading through the entire topology!

 

Network pseudonodes never have SRLGs.

 

Link attributes are most easily seen with the show mpls traffic-eng topology affinity command, which omits most of the other link data.

 

Network pseudonodes never have attributes.

 

Topology Filtering

It's often helpful to filter the output of the TE topology show commands to make it easier to find what you're looking for.

  • The ospf and isis filters can be used to limit output to a single IGP type.
  • The instance <instance> filter limits output to a single IGP instance.
  • The ospf instance <instance> area <area-id> and isis instance <instance> level <level> filters limit output to a single igp-area.
  • The ospf <router-id> and isis <node-id> filters restrict output to a single topology node.
  • The show mpls traffic-eng topology <IP address> command limits output to nodes where:                 
    • the node's router-id matches the supplied address
    • the node has a link whose local address matches the supplied address.

 

Bandwidths

Link bandwidths may be inspected with the full show mpls traffic-eng topology command (with no restrictions). A brief example of the output:

 

IGP Id: 102.0.0.2, MPLS TE Id: 102.0.0.2 Router Node  (OSPF 0 area 1)

  Link[1]:Point-to-Point, Nbr IGP Id:103.0.0.3, Nbr Node Id:5, gen:194210
      Frag Id:20, Intf Address:12.4.4.2, Intf Id:0
      Nbr Intf Address:12.4.4.3, Nbr Intf Id:0
      TE Metric:1, IGP Metric:1, Attribute Flags:0x42
      Attribute Names: red yellow 
      Switching Capability:None, Encoding:unassigned
      BC Model ID:RDM
      Physical BW:155520 (kbps), Max Reservable BW Global:200000 (kbps)
      Max Reservable BW Sub:100000 (kbps)
                                 Global Pool       Sub Pool
               Total Allocated   Reservable        Reservable
               BW (kbps)         BW (kbps)         BW (kbps)
               ---------------   -----------       ----------
        bw[0]:            0         200000           100000
        bw[1]:            0         200000           100000
        bw[2]:            0         200000           100000
        bw[3]:        50000         150000           100000
        bw[4]:            0         150000           100000
        bw[5]:            0         150000           100000
        bw[6]:            0         150000           100000
        bw[7]:        10000         140000           100000

 

  • The physical bandwidth is learned by TE from the router infrastructure, and depends on the hardware of the interface itself.
  • The maximum reservable bandwidths are configured under RSVP
  • The allocated bandwidths at each priority are allocated to tunnels already established in the network
  • The global and sub-pool reservable bandwidths are calculated according to the available bandwidth at each priority level, bearing in mind that lower-priority tunnels could be pre-empted if necessary.

 

Other flooding-related issues

 

Flooding Thresholds

 

When bandwidth changes occur on a link, in principle TE should flood these changes into the network to ensure other routers can carry out cSPF calculation accurately. However, when there are many tunnels, it is also desirable to suppress unnecessary updates to avoid overloading the network. Flooding thresholds are a way to address this.

 

Flooding thresholds are configured as a percentages of the total  bandwidth available on a link. When bandwidth changes occur on a link (usually due to tunnels being admitted or going down), the local LSA  information will only be regenerated and flooded immediately if  the bandwidth change crosses a flooding threshold. There are separate  thresholds for ingress and egress bandwidths on each link.

 

Flooding thresholds may be examined with the show mpls traffic-eng link-management bandwidth-allocation command. Only one link is displayed here, for brevity:

 


 
RP/0/0/CPU0:te-ma3#show mpls traffic-eng link-management bandwidth-allocation Wed Jul 28 20:59:37.093 UTC   System Information::       Links Count         : 8       Bandwidth Hold time : 15 seconds   Link ID:: POS0/5/0/0 (12.0.0.1)     Local Intf ID: 15     Link Status:       Link Label Type     : PSC       Physical BW         : 155520 kbits/sec       BCID                : RDM       Max Reservable BW   : 200000 kbits/sec (reserved: 30% in, 30% out)       BC0 (Res. Global BW): 200000 kbits/sec (reserved: 30% in, 30% out)       BC1 (Res. Sub BW)   : 100000 kbits/sec (reserved: 0% in, 0% out)       SRLGs               : 20, 30       MPLS TE Link State  : MPLS TE on, RSVP on, admin-up       Flooded in areas    : OSPF 0 area 1       Inbound Admission   : allow-all       Outbound Admission  : allow-if-room       IGP Neighbor Count  : 1       BW Descriptors      : 2 (including 0 BC0 descriptors)       Up Thresholds       : 15 30 45 60 75 80 85 90 95 96 97 98 99 100 (default)       Down Thresholds     : 100 99 98 97 96 95 90 85 80 75 60 45 30 15 (default)       Bandwidth Information::         Downstream BC0 (kbits/sec):         KEEP PRIORITY BW HELD    BW TOTAL HELD BW LOCKED  BW TOTAL LOCKED         ------------- ---------- ------------- ---------- ---------------                     0          0             0          0               0                     1          0             0          0               0                     2          0             0          0               0                     3          0             0      50000           50000                     4          0             0          0           50000                     5          0             0          0           50000                     6          0             0          0           50000                     7          0             0      10000           60000         Downstream BC1 (kbits/sec):         KEEP PRIORITY BW HELD    BW TOTAL HELD BW LOCKED  BW TOTAL LOCKED         ------------- ---------- ------------- ---------- ---------------                     0          0             0          0               0                     1          0             0          0               0                     2          0             0          0               0                     3          0             0          0               0                     4          0             0          0               0                     5          0             0          0               0                     6          0             0          0               0                     7          0             0          0               0

 

Flooding thresholds may be configured with the flooding thresholds command under the interface in the main TE submode.

 

A consequence of flooding thresholds is that when small bandwidth changes occur on a link, these may not be immediately flooded and there may therefore be discrepancies between the link bandwidths known to TE and those flooded to the rest of the network. A comparison between the outputs of show mpls traffic-eng link-management interfaces (or show mpls traffic-eng link-management bandwidth-allocation) and show mpls traffic-eng link-management advertisements will reveal such a discrepancy, if it exists.

 

TE will periodically update and re-flood the local LSA to the network in each IGP-area if any change, however small, has occurred since it was last flooded; this is how small bandwidth changes are advertized to the network even if they don't cross a flooding threshold. The time remaining until this occurs is shown by the header of show mpls traffic-eng link-management advertisements:

 

TE will also flood immediately if admission fails on a tunnel during signaling, to ensure that the topology is up-to-date throughout the network and prevent another node repeatedly finding the same, invalid path for a tunnel.

 

RP/0/7/CPU0:te-ma2#show mpls tr li adv
Wed Jul 28 13:45:19.470 UTC

  Flooding Status             : ready
  Last Flooding               : 7107 seconds ago
  Last Flooding Trigger       : Periodic timer expired
  Next Periodic Flooding In   : 93 seconds 
  Diff-Serv TE Mode           : Prestandard 
  Configured Areas            : 2

 

The Next Periodic Flooding In indicates the interval until the flooding timer next expires. The period of this timer may be adjusted with the link-management timers periodic-flooding configuration command in the main TE submode.

 

Flooding may also be forced manually with the mpls traffic-eng link-management flood command:

 


 
RP/0/7/CPU0:te-ma2#mpls traffic-eng link-management flood Wed Jul 28 13:48:09.483 UTC RP/0/7/CPU0:te-ma2#show mpls tr li adv                    Wed Jul 28 13:48:16.474 UTC   Flooding Status             : ready   Last Flooding               : 7 seconds ago   Last Flooding Trigger       : User triggered   Next Periodic Flooding In   : 96 seconds   Diff-Serv TE Mode           : Prestandard   Configured Areas            : 2

 

Note that the reason for the last LSA update is now "User triggered".

 

 

Bandwidth Rounding

 

When large bandwidths are in use, small rounding errors may be  observed in the flooded advertisements, so that the flooded bandwidths don't quite match the configured or calculated ones. This is a result of the conversion between integers (used in config and internally) and  IEEE_FLOAT encodings (flooded).

 

Link bandwidths are stored as 64-bit values in TE. The relevant RFCs on flooding TE data in OSPF and IS-IS specify that flooded bandwidth are encoded as IEEE float values. When these are put into the TE topology, they are converted back into 64-bit integers in the process. This applies to locally-derived bandwidths as well as those received from other routers; they are also converted from  64-bit to IEEE-float and back to 64-bit.

 

Rounding errors may occur during the process with very large bandwidths. There are two things to note about this:

  • The errors involved are very small compared to the link bandwidths themselves, so the likely impact is negligible
  • This can't be fixed without major changes to the RSVP protocol and the relevant standards.

 

A bandwidth of 100000000000, if converted to IEEE-float and back using a web page that does this, becomes 0x51ba43b7 (IEEE) and then 9.9999998E10, which is very slightly less than what we started with.

 

OSPF Flooding on Broadcast Interfaces

 

OSPF is optimized to start advertising the DR's connection to the  network pseudonode when the DR forms the first adjacency. OSPF does not  stop advertising the DR's connection to the network node when DR looses its last adjacency. This is by design, and is done to reduce the number  of updates the OSPF sends to TE. This means that on the DR, TE will  still advertise the link in its own LSA even when there's no adjacencies over the  link in question. Since the generated pseudonode for the LAN will have no links to anything else this won't cause a problem (other than  unnecessarily cluttering up the topology) - but nevertheless it's perhaps not what users would expect. There are no plans to change this behavior.

 

Multiple Adjacencies on Broadcast Interfaces

The original TE implementation was written to run over only one  IGP-area at a time. Multi-area and multi-IGP support have been added subsequently. A consequence of this is that the network type (p2p/broadcast) was originally considered to be an interface property; however, the addition of multi-area/IGP support means that this has become a property of the individual neighbor.

 

TE was fixed to handle different adjacency types over one interface properly in 3.8.0. In older releases, it is necessary to ensure that the network type is the same for all IGP adjacencies on the link; the best way to do this is to configure the IGP to form P2P adjacencies in all areas.

 

The reason for this is that LAN interfaces are usually configured back-to-back (ie p2p) in real networks, and the IGPs have optimizations which may be configured to treat these links as p2p. This means that network pseudonodes are no longer generated and flooded, which reduces  the overall size and complexity of the network topology. This in turn means that less resources are used and path calculations are quicker. This benefits both the IGPs themselves and TE (if it's running over the IGP).

 

This doesn't affect interfaces that are P2P by default (e.g. POS) as there's no way to have broadcast adjacencies formed over them, so the issue doesn't arise.

 

A particular example of this is the OSPF multi-adjacency feature. In this feature, a primary adjacency is set up over the link in  one area, and then other MADJ adjacencies are formed which are dependent on this. The MADJ adjacencies are always p2p; the primary adjacency, however, will be the usual type for the interface in question.

 

RP/0/0/CPU0:te-ma1#show run router ospf
Thu Jul 29 20:32:04.879 UTC
router ospf madj
 router-id 101.1.1.1
 area 0
  mpls traffic-eng
  interface GigabitEthernet0/2/0/1
  !
 !
 area 1
  mpls traffic-eng
  multi-area-interface GigabitEthernet0/2/0/1
  !
 !
 area 2
  mpls traffic-eng
  multi-area-interface GigabitEthernet0/2/0/1
  !
 !
 area 3
  mpls traffic-eng
  multi-area-interface GigabitEthernet0/2/0/1
  !
 !
 mpls traffic-eng router-id Loopback1
!

RP/0/0/CPU0:te-ma1#show run router isis
Thu Jul 29 20:32:08.677 UTC
router isis 0
 net 49.0001.0011.0111.00
 nsf ietf
 log adjacency changes
 address-family ipv4 unicast
  metric-style wide
  mpls traffic-eng level-1-2
  mpls traffic-eng router-id Loopback1
 !
 interface GigabitEthernet0/2/0/1
  address-family ipv4 unicast
  !
 !
!

 

 

In this example, GigabitEthernet0/2/0/1 has broadcast  adjacencies in IS-IS level-1 and level-2 and in OSPF area 0 (the primary area for OSPF), but p2p adjacencies in the other OSPF areas:

 

RP/0/0/CPU0:te-ma1#show isis neighbors 
Thu Jul 29 20:34:31.543 UTC

IS-IS 0 neighbors:
System Id      Interface        SNPA           State Holdtime Type IETF-NSF
te-ma2         Gi0/2/0/1        0090.86a9.18fd Up    8        L1L2 Capable 

Total neighbor count: 1

RP/0/0/CPU0:te-ma1#show ospf neighbor        
Thu Jul 29 20:36:45.987 UTC

* Indicates MADJ interface

Neighbors for OSPF madj

Neighbor ID     Pri   State           Dead Time   Address         Interface
102.1.1.2       1     FULL/DR         00:00:39    11.1.1.2        GigabitEthernet0/2/0/1
    Neighbor is up for 00:06:38
102.1.1.2       1     FULL/  -        00:00:39    11.1.1.2        GigabitEthernet0/2/0/1*
    Neighbor is up for 00:06:39
102.1.1.2       1     FULL/  -        00:00:31    11.1.1.2        GigabitEthernet0/2/0/1*
    Neighbor is up for 00:06:36
102.1.1.2       1     FULL/  -        00:00:31    11.1.1.2        GigabitEthernet0/2/0/1*
    Neighbor is up for 00:06:38

Total neighbor count: 4

 

show ospf neighbor detail gives the area for each adjacency.

 

This is what the link looks like in TE:

 

RP/0/0/CPU0:te-ma1#show mpls traffic-eng link-management interfaces GigabitEthernet0/2/0/1
Thu Jul 29 20:40:16.465 UTC

  System Information:: 
      Links Count         : 9 (Maximum Links Supported 250) 

  Link ID:: GigabitEthernet0/2/0/1 (11.1.1.1)
    Local Intf ID: 27
    Link Status:

      Link Label Type     : PSC
      Physical BW         : 1000000 kbits/sec
      BCID                : RDM 
      Max Reservable BW   : 200000 kbits/sec (reserved: 0% in, 0% out)
      BC0 (Res. Global BW): 200000 kbits/sec (reserved: 0% in, 0% out)
      BC1 (Res. Sub BW)   : 100000 kbits/sec (reserved: 0% in, 0% out)
      MPLS TE Link State  : MPLS TE on, RSVP on, admin-up
      Inbound Admission   : reject-huge
      Outbound Admission  : allow-if-room
      IGP Neighbor Count  : 6
      Max Res BW (RDM)    : 200000 kbits/sec
      BC0 (RDM)           : 200000 kbits/sec
      BC1 (RDM)           : 100000 kbits/sec
      Max Res BW (MAM)    : 500000 kbits/sec
      BC0 (MAM)           : 200000 kbits/sec
      BC1 (MAM)           : 100000 kbits/sec
      Attributes          : 0x0
      Attribute Names     : 
      Flooding Status: (6 area)
        IGP Area[1]: OSPF madj area 3, flooded
          Nbr: ID 102.1.1.2, IP 11.1.1.2 (Up)
          Admin weight: not set (TE), 1 (IGP)
        IGP Area[2]: OSPF madj area 2, flooded
          Nbr: ID 102.1.1.2, IP 11.1.1.2 (Up)
          Admin weight: not set (TE), 1 (IGP)
        IGP Area[3]: OSPF madj area 1, flooded
          Nbr: ID 102.1.1.2, IP 11.1.1.2 (Up)
          Admin weight: not set (TE), 1 (IGP)
        IGP Area[4]: OSPF madj area 0, flooded
          Nbr: ID 11.1.1.2, IP 0.0.0.0 (Up)
          Admin weight: not set (TE), 1 (IGP)
        IGP Area[5]: IS-IS 0 level 2, flooded
          Nbr: ID 0002.0002.0022.03, IP 11.1.1.2 (Up)
          Admin weight: not set (TE), 10 (IGP)
        IGP Area[6]: IS-IS 0 level 1, flooded
          Nbr: ID 0002.0002.0022.03, IP 11.1.1.2 (Up)
          Admin weight: not set (TE), 10 (IGP)

RP/0/0/CPU0:te-ma1#show mpls traffic-eng link-management igp-neighbors interface GigabitEthernet0/2/0/1
Thu Jul 29 20:43:22.687 UTC

  Link ID:: GigabitEthernet0/2/0/1
    Neighbor ID: 0002.0002.0022.03 (IS-IS 0 level 2, link address: 11.1.1.2)
    Neighbor ID: 102.1.1.2 (OSPF madj area 2, link address: 11.1.1.2)
    Neighbor ID: 11.1.1.2 (OSPF madj area 0, link address: 0.0.0.0)
    Neighbor ID: 102.1.1.2 (OSPF madj area 3, link address: 11.1.1.2)
    Neighbor ID: 102.1.1.2 (OSPF madj area 1, link address: 11.1.1.2)
    Neighbor ID: 0002.0002.0022.03 (IS-IS 0 level 1, link address: 11.1.1.2)

 

And here are the advertisements for that interface. Note the difference between the areas in which the link is point-to-point (neighbor information is given) and those where it's broadcast (DR information is supplied).

 

RP/0/0/CPU0:te-ma1#sh mpls traffic-eng link-management advertisements 
Thu Jul 29 20:45:46.243 UTC

  Flooding Status             : ready
  Last Flooding               : 10 seconds ago
  Last Flooding Trigger       : Periodic timer expired
  Next Periodic Flooding In   : 158 seconds 
  Diff-Serv TE Mode           : Prestandard 
  Configured Areas            : 7

  IGP Area[1]:: OSPF madj area 3
      Flooding Protocol   : OSPF
      IGP System ID       : 101.1.1.1
      MPLS TE Router ID   : 101.1.1.1
      Flooded Links       : 1

      Link ID:: 0 (GigabitEthernet0/2/0/1)
          Link IP Address      : 11.1.1.1
          O/G Intf ID          : 27
          Neighbor             : ID 102.1.1.2, IP 11.1.1.2
          TE Metric            : 1
          IGP Metric           : 1
          Physical BW          : 1000000 kbits/sec
          BCID                 : RDM 
          Max Reservable BW    : 200000 kbits/sec
          Res Global BW        : 200000 kbits/sec
          Res Sub BW           : 100000 kbits/sec

          Downstream::
                                Global Pool   Sub Pool   
                                -----------   -----------
            Reservable BW[0]:        200000        100000  kbits/sec
            Reservable BW[1]:        200000        100000  kbits/sec
            Reservable BW[2]:        200000        100000  kbits/sec
            Reservable BW[3]:        200000        100000  kbits/sec
            Reservable BW[4]:        200000        100000  kbits/sec
            Reservable BW[5]:        200000        100000  kbits/sec
            Reservable BW[6]:        200000        100000  kbits/sec
            Reservable BW[7]:        200000        100000  kbits/sec

          Attribute Flags: 0x00000000
          Attribute Names: 

  IGP Area[2]:: OSPF madj area 2
      Flooding Protocol   : OSPF
      IGP System ID       : 101.1.1.1
      MPLS TE Router ID   : 101.1.1.1
      Flooded Links       : 1

      Link ID:: 0 (GigabitEthernet0/2/0/1)
          Link IP Address      : 11.1.1.1
          O/G Intf ID          : 27
          Neighbor             : ID 102.1.1.2, IP 11.1.1.2
          TE Metric            : 1
          IGP Metric           : 1
          Physical BW          : 1000000 kbits/sec
          BCID                 : RDM 
          Max Reservable BW    : 200000 kbits/sec
          Res Global BW        : 200000 kbits/sec
          Res Sub BW           : 100000 kbits/sec

          Downstream::
                                Global Pool   Sub Pool   
                                -----------   -----------
            Reservable BW[0]:        200000        100000  kbits/sec
            Reservable BW[1]:        200000        100000  kbits/sec
            Reservable BW[2]:        200000        100000  kbits/sec
            Reservable BW[3]:        200000        100000  kbits/sec
            Reservable BW[4]:        200000        100000  kbits/sec
            Reservable BW[5]:        200000        100000  kbits/sec
            Reservable BW[6]:        200000        100000  kbits/sec
            Reservable BW[7]:        200000        100000  kbits/sec

          Attribute Flags: 0x00000000
          Attribute Names: 

  IGP Area[3]:: OSPF madj area 1
      Flooding Protocol   : OSPF
      IGP System ID       : 101.1.1.1
      MPLS TE Router ID   : 101.1.1.1
      Flooded Links       : 1

      Link ID:: 0 (GigabitEthernet0/2/0/1)
          Link IP Address      : 11.1.1.1
          O/G Intf ID          : 27
          Neighbor             : ID 102.1.1.2, IP 11.1.1.2
          TE Metric            : 1
          IGP Metric           : 1
          Physical BW          : 1000000 kbits/sec
          BCID                 : RDM 
          Max Reservable BW    : 200000 kbits/sec
          Res Global BW        : 200000 kbits/sec
          Res Sub BW           : 100000 kbits/sec

          Downstream::
                                Global Pool   Sub Pool   
                                -----------   -----------
            Reservable BW[0]:        200000        100000  kbits/sec
            Reservable BW[1]:        200000        100000  kbits/sec
            Reservable BW[2]:        200000        100000  kbits/sec
            Reservable BW[3]:        200000        100000  kbits/sec
            Reservable BW[4]:        200000        100000  kbits/sec
            Reservable BW[5]:        200000        100000  kbits/sec
            Reservable BW[6]:        200000        100000  kbits/sec
            Reservable BW[7]:        200000        100000  kbits/sec

          Attribute Flags: 0x00000000
          Attribute Names: 

  IGP Area[4]:: OSPF madj area 0
      Flooding Protocol   : OSPF
      IGP System ID       : 101.1.1.1
      MPLS TE Router ID   : 101.1.1.1
      Flooded Links       : 1

      Link ID:: 0 (GigabitEthernet0/2/0/1)
          Link IP Address      : 11.1.1.1
          O/G Intf ID          : 27
          Designated Router    : 11.1.1.2
          TE Metric            : 1
          IGP Metric           : 1
          Physical BW          : 1000000 kbits/sec
          BCID                 : RDM 
          Max Reservable BW    : 200000 kbits/sec
          Res Global BW        : 200000 kbits/sec
          Res Sub BW           : 100000 kbits/sec

          Downstream::
                                Global Pool   Sub Pool   
                                -----------   -----------
            Reservable BW[0]:        200000        100000  kbits/sec
            Reservable BW[1]:        200000        100000  kbits/sec
            Reservable BW[2]:        200000        100000  kbits/sec
            Reservable BW[3]:        200000        100000  kbits/sec
            Reservable BW[4]:        200000        100000  kbits/sec
            Reservable BW[5]:        200000        100000  kbits/sec
            Reservable BW[6]:        200000        100000  kbits/sec
            Reservable BW[7]:        200000        100000  kbits/sec

          Attribute Flags: 0x00000000
          Attribute Names: 

  IGP Area[5]:: IS-IS 0 level 2
      Flooding Protocol   : IS-IS
      IGP System ID       : 0001.0011.0111
      MPLS TE Router ID   : 101.1.1.1
      Flooded Links       : 1

      Link ID:: 0 (GigabitEthernet0/2/0/1)
          Link IP Address      : 11.1.1.1
          O/G Intf ID          : 27
          Designated Router    : 0002.0002.0022.03, IP 11.1.1.2
          TE Metric            : 10
          IGP Metric           : 10
          Physical BW          : 1000000 kbits/sec
          BCID                 : RDM 
          Max Reservable BW    : 200000 kbits/sec
          Res Global BW        : 200000 kbits/sec
          Res Sub BW           : 100000 kbits/sec

          Downstream::
                                Global Pool   Sub Pool   
                                -----------   -----------
            Reservable BW[0]:        200000        100000  kbits/sec
            Reservable BW[1]:        200000        100000  kbits/sec
            Reservable BW[2]:        200000        100000  kbits/sec
            Reservable BW[3]:        200000        100000  kbits/sec
            Reservable BW[4]:        200000        100000  kbits/sec
            Reservable BW[5]:        200000        100000  kbits/sec
            Reservable BW[6]:        200000        100000  kbits/sec
            Reservable BW[7]:        200000        100000  kbits/sec

          Attribute Flags: 0x00000000
          Attribute Names: 

  IGP Area[6]:: IS-IS 0 level 1
      Flooding Protocol   : IS-IS
      IGP System ID       : 0001.0011.0111
      MPLS TE Router ID   : 101.1.1.1
      Flooded Links       : 1

      Link ID:: 0 (GigabitEthernet0/2/0/1)
          Link IP Address      : 11.1.1.1
          O/G Intf ID          : 27
          Designated Router    : 0002.0002.0022.03, IP 11.1.1.2
          TE Metric            : 10
          IGP Metric           : 10
          Physical BW          : 1000000 kbits/sec
          BCID                 : RDM 
          Max Reservable BW    : 200000 kbits/sec
          Res Global BW        : 200000 kbits/sec
          Res Sub BW           : 100000 kbits/sec

          Downstream::
                                Global Pool   Sub Pool   
                                -----------   -----------
            Reservable BW[0]:        200000        100000  kbits/sec
            Reservable BW[1]:        200000        100000  kbits/sec
            Reservable BW[2]:        200000        100000  kbits/sec
            Reservable BW[3]:        200000        100000  kbits/sec
            Reservable BW[4]:        200000        100000  kbits/sec
            Reservable BW[5]:        200000        100000  kbits/sec
            Reservable BW[6]:        200000        100000  kbits/sec
            Reservable BW[7]:        200000        100000  kbits/sec

          Attribute Flags: 0x00000000
          Attribute Names: 

 

Other topology-related issues

 

Effect of router-id and area changes on TE

 

Some network changes can, as a result of the way link-state protocols work, result in stale router node LSAs being present in the network. These can cause problems in TE's tunnel path calculations and although the network will eventually purge them, it can be difficult to repair the network in a timely manner. This section explains the problems that may occur, how to recover from them in a timely manner and how to avoid or minimize them in the first place.

 

LSA lifetimes

 

In link-state protocols, LSAs are generated by each router and flooded throughout the network. Each LSA has a lifetime, which is set by the originating router, and is periodically refreshed by the originating router. If an LSA is not refreshed for the period of its lifetime after a router last received a new version of it, that router will purge the LSA from its LSA DB. This will typically happen at around the same time for all routers in a network if a LSA is not refreshed, as LSA flooding is a rapid process.

 

The LSA refresh-interval and timeout are typically chosen so that one or two refreshes may be missed without an LSA being removed from the network; default refresh intervals are 20 minutes for IS-IS and 30 minutes for OSPF (assuming no changes have been made to the LSA in the meantime) and the default LSA lifetime is an hour for both IGPs. LSA generation, flooding and timeout is done independently in each area/level of the network.

 

Creation and effect of stale LSAs

 

It is possible for a router to be removed from an area in such a way that it does not have a chance to remove its own LSAs from the network. In this case, the router's generated LSAs will remain in the network until they time out and are purged.

 

This may occur if a router is moved from one area to another, in which case a stale LSA will remain in the old area. It may also occur if a router's IGP router ID is changed. From the point of view of the network, this looks like the sudden disappearance of one router and the creation of another.

 

In both these cases the router represented by the stale LSA will become unreachable as soon as its neighbors' adjacencies to it time out and those links are withdrawn from the network. This means that the IGPs' SPF calculations will be unaffected by the stale LSAs. However, TE's cSPF calculations may be affected by the stale LSAs as TE initially attempts to find the destination router-id for a tunnel in each candidate IGP-area. If this TE-router-id is present in a stale LSA, cSPF will fail as the node will still be unreachable.

 

In the case of intra-area tunnels or expanded loose hops in an inter-area tunnel, this may cause erroneous PCALC errors if the tunnel destination is now supposed to be unavailable; TE will report that there is no path to the destination, rather than the destination being not found.

 

A stale LSA may also prevent an inter-area tunnel being identified as such. TE identifies a tunnel as inter-area if its path contains at least one loose hop and its destination is not present in any local area. If the destination is found in a local area due to its presence in stale LSA, TE will not identify the tunnel as being inter-area.

 

Purging Stale LSAs from a Network

 

The first (and easiest) way to purge stale LSAs from the network is simply to wait. As explained above, they will eventually be removed. This may take up to an hour with default timer configs on all routers.

 

If more rapid purging is required, the only way to do this is to completely de-configure the IGP on all routers in the network, and then reconfigure it on all routers. It is essential that all routers are de-configured before any are reconfigured as otherwise the stale LSA will be re-flooded through the network by the routers that have not yet been taken down. Link-state protocols are specifically designed to ensure that every router in the network has an up-to-date and complete copy of the LSA DB.

 

Avoiding or Minimizing Problems

 

The LSA refresh interval and lifetime in OSPF are fixed to 30 and 60 minutes respectively, and cannot be changed in XR. However, in IS-IS they are both configurable, and this means that the problems caused by stale LSAs in the network can be minimized for IS-IS. This is done by shortening the LSA lifetime before any changes are made, making the appropriate changes to the network, and finally restoring the default values.

 

RP/0/0/CPU0:te-ma1#conf
RP/0/0/CPU0:te-ma1(config)#router isis 0
RP/0/0/CPU0:te-ma1(config-isis)#max-lsp-lifetime ?
  <1-65535>  Maximum LSP lifetime in seconds
RP/0/0/CPU0:te-ma1(config-isis)#max-lsp-lifetime 30 ?
  level  Set LSP regeneration interval for one level only
  <cr>   
RP/0/0/CPU0:te-ma1(config-isis)#max-lsp-lifetime 30 
RP/0/0/CPU0:te-ma1(config-isis)#lsp-refresh-interval ?
  <1-65535>  LSP refresh time in seconds
RP/0/0/CPU0:te-ma1(config-isis)#lsp-refresh-interval 20 ?
  level  Set LSP refresh interval for one level only
  <cr>   
RP/0/0/CPU0:te-ma1(config-isis)#lsp-refresh-interval 20 
RP/0/0/CPU0:te-ma1(config-isis)#commit

 

This configures the router to refresh its own LSAs every 20 seconds, and ensures that other routers will time them out if they're not refreshed after 30 seconds. It is only necessary to do this on the router where the major config changes are to take place. Care must be taken to avoid setting the LSA lifetime to less than the LSA refresh interval, or the network will periodically lose the node where this is done.

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