OSPF Routes are in the OSPF Database but not in the Routing Table

Answered Question
Sep 16th, 2010

Dear Members,

i have a problem with redistributing OSPF routes in my MPLS VPN. My local routes are redistributed into the MPLS VPN which is running BGP. This is the configuration of the edge router.

!

hostname CU_EDGE01

!

ip vrf CU_A

rd 100:26

route-target export 100:26

route-target import 100:26

!

interface Loopback0

ip address 1.1.1.252 255.255.255.255

ip router isis

!

interface FastEthernet0/0

description LINK TO Customer Router 01 FA0/0

no ip address

speed 100

full-duplex

!

interface FastEthernet0/0.26

encapsulation dot1Q 26

ip vrf forwarding CU_A

ip address 172.16.2.5 255.255.255.252

!

interface FastEthernet0/1

description LINK TO P_ROUTER_FA0/0

ip address 1.1.1.2 255.255.255.252

ip router isis

speed 100

full-duplex

mpls ip

!

router ospf 100 vrf CU_A

log-adjacency-changes

redistribute bgp 100 metric 20 subnets

network 172.16.2.4 0.0.0.3 area 0

!

router isis

net 41.0000.0000.0004.00

is-type level-1

!

router bgp 100

no bgp default ipv4-unicast

bgp log-neighbor-changes

neighbor 1.1.1.251 remote-as 100

neighbor 1.1.1.251 update-source Loopback0

!

address-family ipv4

neighbor 1.1.1.251 activate

no auto-summary

no synchronization

exit-address-family

!

address-family vpnv4

neighbor 1.1.1.251 activate

neighbor 1.1.1.251 send-community both

exit-address-family

!

address-family ipv4 vrf CU_A

redistribute ospf 100 vrf CU_A match internal external 1 external 2

no synchronization

exit-address-family

the routes are redistributed in the BGP process as desired. See the output.

CU_EDGE01#show ip bgp vpnv4 all
BGP table version is 9, local router ID is 1.1.1.252
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
              r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete

   Network          Next Hop            Metric LocPrf Weight Path
Route Distinguisher: 100:26 (default for vrf CU_A)
*>i10.2.2.0/24      1.1.1.251               11    100      0 ?
*> 10.3.0.1/32      172.16.2.6               2         32768 ?
*> 172.16.2.4/30    0.0.0.0                  0         32768 ?
*>i172.16.20.4/30   1.1.1.251                0    100      0 ?
CU_EDGE01#

Also in the OSPF Database i can see the routes.

CU_EDGE01#show ip ospf database

            OSPF Router with ID (172.16.2.5) (Process ID 100)

                Router Link States (Area 0)

Link ID         ADV Router      Age         Seq#       Checksum Link count
172.16.2.5      172.16.2.5      30          0x80000002 0x007AA4 1
172.16.2.6      172.16.2.6      31          0x80000002 0x0072AB 1

                Net Link States (Area 0)

Link ID         ADV Router      Age         Seq#       Checksum
172.16.2.6      172.16.2.6      31          0x80000001 0x000526

                Summary Net Link States (Area 0)

Link ID         ADV Router      Age         Seq#       Checksum
10.2.2.0        172.16.2.5      17          0x80000001 0x005B7B
10.3.0.1        172.16.2.6      66          0x80000001 0x001E4B
172.16.20.4     172.16.2.5      17          0x80000001 0x006FA3

The route from the far end is the 10.2.2.0/24. The down bit is also set.


CU_EDGE01#show ip ospf database summary 10.2.2.0

            OSPF Router with ID (172.16.2.5) (Process ID 100)

                Summary Net Link States (Area 0)

  LS age: 134
  Options: (No TOS-capability, DC, Downward)
  LS Type: Summary Links(Network)
  Link State ID: 10.2.2.0 (summary Network Number)
  Advertising Router: 172.16.2.5
  LS Seq Number: 80000001
  Checksum: 0x5B7B
  Length: 28
  Network Mask: /24
        TOS: 0  Metric: 20

in the routing table of the vrf CU_A i see the routes. My qestion here is, why the route to 10.2.20/24 is a BGP route and not a OSPF route?

CU_EDGE01#show ip route vrf CU_A

Routing Table: CU_A
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route

Gateway of last resort is not set

     172.16.0.0/30 is subnetted, 2 subnets
B       172.16.20.4 [200/0] via 1.1.1.251, 00:02:57
C       172.16.2.4 is directly connected, FastEthernet0/0.26
     10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
O IA    10.3.0.1/32 [110/2] via 172.16.2.6, 00:03:05, FastEthernet0/0.26
B       10.2.2.0/24 [200/11] via 1.1.1.251, 00:02:57
CU_EDGE01#

on the local router the routes are also in the OSPF Database

CU_RT1#show ip ospf database

            OSPF Router with ID (172.16.2.6) (Process ID 100)

                Router Link States (Area 0)

Link ID         ADV Router      Age         Seq#       Checksum Link count
172.16.2.5      172.16.2.5      258         0x80000002 0x007AA4 1
172.16.2.6      172.16.2.6      258         0x80000002 0x0072AB 1

                Net Link States (Area 0)

Link ID         ADV Router      Age         Seq#       Checksum
172.16.2.6      172.16.2.6      258         0x80000001 0x000526

                Summary Net Link States (Area 0)

Link ID         ADV Router      Age         Seq#       Checksum
10.2.2.0        172.16.2.5      245         0x80000001 0x005B7B
10.3.0.1        172.16.2.6      293         0x80000001 0x001E4B
172.16.20.4     172.16.2.5      245         0x80000001 0x006FA3

                Router Link States (Area 10)

Link ID         ADV Router      Age         Seq#       Checksum Link count
172.16.2.6      172.16.2.6      298         0x80000001 0x00C9CF 1

                Summary Net Link States (Area 10)

Link ID         ADV Router      Age         Seq#       Checksum
172.16.2.4      172.16.2.6      301         0x80000001 0x00F8BE

                Summary ASB Link States (Area 10)

Link ID         ADV Router      Age         Seq#       Checksum
172.16.2.5      172.16.2.6      261         0x80000001 0x00F2BF
CU_RT1#

but on the routing table for the vrf CU_A i cannot see the route to 10.2.2.0/24

CU_RT1#show ip route vrf CU_A

Routing Table: CU_A
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route

Gateway of last resort is not set

     172.16.0.0/30 is subnetted, 1 subnets
C       172.16.2.4 is directly connected, FastEthernet0/0.26
     10.0.0.0/16 is subnetted, 1 subnets
C       10.3.0.0 is directly connected, Loopback103
CU_RT1#

Does anybody has an explaination for the missing OSPF routes?

Thank you very much in advanced

Alex

I have this problem too.
0 votes
Correct Answer by Lei Tian about 6 years 4 months ago

Hi Alex,

The prefix with down bit set will not be put in RIB. This is done by default to prevent loop. Did you have 'capability vrf-lite' configured on CE? You need this command on CE to receive a LSA with down bit, when using multi-vrf.

http://www.cisco.com/en/US/docs/ios/12_0st/12_0st21/feature/guide/ospfvrfl.html#wp1039220

HTH,

Lei Tian

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 5 (1 ratings)
Loading.

Actions

This Discussion