how to enable the RSVP protocol in TE?

Unanswered Question
Jul 31st, 2008

ip rsvp bandwidth xxx? or something else?

how to maintain the relationship?

I have this problem too.
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lee.reade Thu, 07/31/2008 - 01:43

Hi,

To enable RSVP for MPLS TE all you need to do is specifiy the command " ip rsvp bandwidth" on the interface, you do not have to set the actual bandwidth that you want RSVP to use, as by default it will use 75% of the link bandwidth.

There are no neighbour relationships formed for RSVP.

Check out;

http://www.cisco.com/en/US/docs/ios/zz_trash/me_te_diffserv_aw_ps6350_TSD_Products_Configuration_Guide_Chapter.html

HTH

LR

wlsj Thu, 07/31/2008 - 16:45

is it TE relationship ?

R6#show ip rsvp neighbor

56.1.1.5 RSVP

67.1.1.7 RSVP

n.nandrekar Thu, 07/31/2008 - 01:53

hi!

When on an tunnel interface, you enable "tunnel mode mpls traffic-eng" it starts to establish the tunnel through RSVP-TE.

For calculating the path to the destination, the head-end router should know the constraints like bandwidth available reserved etc for the whole topology. This is distributed by OSPF-TE or ISIS-TE.

But not all links are included to create this topology database. Only links which are enabled for traffic engineering using the interface config command " mpls traffic-eng tunnels" are used.

The ip rsvp bandwidth command on the interface denotes how much bandwidth is used for calculation in the TE database.

this link gives more details :

http://www.ciscopress.com/articles/article.asp?p=426640&seqNum=4

Regards,

Niranjan

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wlsj Thu, 07/31/2008 - 16:43

hi,

Configure RSVP bandwidth parameters that will be used on the interface for 'signaling purposes' and resource allocation for traffic engineered sessions. Figure 9-13 outlines the configurations that need to be performed on the interface.

n.nandrekar Thu, 07/31/2008 - 21:49

hi!

The "sh mpls traffic-eng tunnels" would be a more useful command to know the TE tunnels established. The " sh ip rsvp nei" shows just the neighbors with whime rsvp neighbership is formed. It could even be a non TE neighborship if just RSVP is being used for some voice applications.

The RSVP bandwidth that you configure on an interface is used for "signaling purposes"... This means that The router communicates that bandwidth to ospf/isis - TE to use in its TE topology table. Everytime a tunnel is formed reserving the bandwidth, the corrosponding bandwidth is deducted from the configured bandwidth in the topology table. So if not enough bandwidth is present during signalling of RSVP-TE tunnel, the tunnel is not established (unless it is a higher priority tunnel and pre-empts other tunnels)

I tried the scenario where I tried to establish a TE tunnel when I had NOT given "ip rsvp bandwidth " on the physical interface. I was able to set up the tunnel as long as I didnot try to reserve the bandwidth for the TE tunnel. The 0 bandwidth TE tunnel comes up. So the "ip rsvp bandwidth" enables "RSVP for IP" i.e. if you want to reserve bandwidth (which we normally do). But to anable TE on the interface you need the command "mpls traffic-eng tunnels"

6506-32-PE3#sh run int se2/3/0

Building configuration...

Current configuration : 313 bytes

!

interface Serial2/3/0

ip address 17.11.78.1 255.255.255.252

ip pim sparse-dense-mode

ip flow ingress

mpls traffic-eng tunnels

mpls traffic-eng backup-path Tunnel60004

mpls ip

dsu bandwidth 44210

framing c-bit

cablelength 10

ip rsvp signalling hello

ip rsvp signalling hello refresh interval 100

end

6506-32-PE3#sh run int tun60003

Building configuration...

Current configuration : 333 bytes

!

interface Tunnel60003

bandwidth 9

ip unnumbered Loopback0

delay 50000

tunnel destination 19.17.18.21

tunnel mode mpls traffic-eng

tunnel mpls traffic-eng autoroute announce

tunnel mpls traffic-eng path-option 1 explicit name Eway3

tunnel mpls traffic-eng path-selection metric te

tunnel mpls traffic-eng fast-reroute

end

6506-32-PE3#sh mpls traffic-eng tunn brief

Signalling Summary:

LSP Tunnels Process: running

Passive LSP Listener: running

RSVP Process: running

Forwarding: enabled

Periodic reoptimization: every 3600 seconds, next in 2351 seconds

Periodic FRR Promotion: Not Running

Periodic auto-bw collection: every 300 seconds, next in 251 seconds

TUNNEL NAME DESTINATION UP IF DOWN IF STATE/PROT

6506-32-PE3_t60003 19.17.18.21 - Se2/3/0 up/up

Displayed 1 (of 1) heads, 0 (of 0) midpoints, 0 (of 0) tails

6506-32-PE3#

To summarize, "ip RSVP bandwidth" is not "mandatory for MPLS TE but will be used in almost all scenarios as we invariably want to reserve bandwidth with TE.

Regards,

Niranjan

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