rsvp and cspf

[krenjt]

Hi guys!

I have a question about rsvp when one router set up a LSP.

Here is a example

IGP is isis and all the routers have all the routes. The family mpls is configured on the interfaces, but only the red links in the topology was configured under [protocol mpls] and [protocol rsvp]

I set up a LSP from r1 to r5 and use a no-cspf option on R1.
The LSP is not established succeefully.
Here is the error information from traceoption on R1:
Apr 4 18:21:13.605729 RSVP PathErr to client
Apr 4 18:21:58.607909 RSVP PathErr to client
Apr 4 18:22:43.608813 RSVP PathErr to client
Apr 4 18:23:28.611029 RSVP PathErr to client
Apr 4 18:24:13.612339 RSVP PathErr to client
Apr 4 18:24:58.613559 RSVP PathErr to client
Apr 4 18:25:43.614860 RSVP PathErr to client
Apr 4 18:26:28.617088 RSVP PathErr to client
Apr 4 18:27:13.618841 RSVP PathErr to client

now i configured a named path test on R1
it constains two strict nodes
R3 strict
R5 strict

what i see now is R1 can send Path message to R3, R3 forwarded it to R4, then the problem occurs , because the address in ERO is not one of R4's address, so R4 send a PattErr massage.

what confused me is:
why R3 forwarded the Path packet to R4, it should forward the packet to R5 based on its igp routing table even though the link between r4 and r5 is not configured under mpls and rsvp.

ThankS!

[jstar]

Are you sure if R3 is forwarding path message to R4?
I just cheked in lab and not seeing this behavior.

In lab, since interface to R5 is not part of rsvp/mpls, R3 itself is sending back the error.

1. From tcpdump , no rsvp path message to R4.

lab@Haf-Arun-re1# run monitor traffic interface fe-1/0/2.30 size 1500    
verbose output suppressed, use <detail> or <extensive> for full protocol decode
Address resolution is ON. Use <no-resolve> to avoid any reverse lookup delay.
Address resolution timeout is 4s.
Listening on fe-1/0/2.30, capture size 1500 bytes

Reverse lookup for 224.0.0.5 failed (check DNS reachability).
Other reverse lookup failures will not be reported.
Use <no-resolve> to avoid reverse lookups on IP addresses.

06:24:41.067950  In IP 30.30.30.1 > 224.0.0.5: OSPFv2, LS-Update, length 92
06:24:41.756728 Out IP 30.30.30.2 > 224.0.0.5: OSPFv2, Hello, length 48
06:24:42.070981 Out IP 30.30.30.2 > 224.0.0.5: OSPFv2, LS-Ack, length 44
06:24:43.030094 Out IP 30.30.30.2 > 224.0.0.5: OSPFv2, LS-Update, length 60
06:24:44.033464  In IP 30.30.30.1 > 224.0.0.5: OSPFv2, LS-Ack, length 44
06:24:45.331681  In IP 30.30.30.1 > 224.0.0.5: OSPFv2, Hello, length 48
06:24:49.431532 Out IP 30.30.30.2 > 224.0.0.5: OSPFv2, Hello, length 48
06:24:53.563404  In IP 30.30.30.1 > 224.0.0.5: OSPFv2, Hello, length 48
06:24:59.418963 Out IP 30.30.30.2 > 224.0.0.5: OSPFv2, Hello, length 48
06:25:02.268963  In IP 30.30.30.1 > 224.0.0.5: OSPFv2, Hello, length 48
06:25:08.991457 Out IP 30.30.30.2 > 224.0.0.5: OSPFv2, Hello, length 48
06:25:11.278604  In IP 30.30.30.1 > 224.0.0.5: OSPFv2, Hello, length 48
06:25:17.749075 Out IP 30.30.30.2 > 224.0.0.5: OSPFv2, Hello, length 48
06:25:19.232007  In IP 30.30.30.1 > 224.0.0.5: OSPFv2, Hello, length 48
06:25:27.198653  In IP 30.30.30.1 > 224.0.0.5: OSPFv2, Hello, length 48
06:25:27.379556 Out IP 30.30.30.2 > 224.0.0.5: OSPFv2, Hello, length 48
06:25:36.329655  In IP 30.30.30.1 > 224.0.0.5: OSPFv2, Hello, length 48
06:25:37.135011 Out IP 30.30.30.2 > 224.0.0.5: OSPFv2, Hello, length 48

 2. Bad strict route reported by R3

lab@Haf-Arun-re1# run show mpls lsp logical-system 1HLR extensive 
Apr 11 06:24:24
Ingress LSP: 1 sessions

4.4.4.4
  From: 1.1.1.1, State: Dn, ActiveRoute: 0, LSPname: test
  ActivePath: (none)
  LSPtype: Static Configured
  LoadBalance: Random
  Encoding type: Packet, Switching type: Packet, GPID: IPv4
  Primary   test             State: Dn
    Priorities: 7 0
    SmartOptimizeTimer: 180
    2 Apr 11 06:24:02.740 20.20.20.2: Explicit Route: bad strict route[7 times] >>>> By R3
    1 Apr 11 06:21:38.728 Originate Call
  Created: Wed Apr 11 06:21:38 2012

Can you please enable traceoptions in R3/R4 and check?
Also check "show mpls lsp extensive" on ingress router?

- Arun Kumar S

[mhariry]

Hi,

Agree with Arun I think R3 will send traffic directly to R5 not R4. Could you confirm by using the following command on R1

show mpls lsp ingress detail

it will display the path exactly check every IP in the path to confirm is R3 send traffic to R5 directly or to R4

Regards,

Mohamed Elhariry

JNCIE-M/T # 1059, CCNP & CCIP

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If this post was helpful, please mark this post as an "Accepted Solution".Kudos are always appreciated!

[jstar]

Hi Mohamed Elhariry

R3 will not send to R5 as rsvp/mpls is not enabled on that link , instead R3 should send back an error...

- Arun

[mhariry]

Hi Arun,

What I believe R3 will send directly to R5 based on IGP and as per Krenjt he mentioned R4 send the error which suppose no traffic passed from R3 to R4

To make it work just configure ERO to R3 either loose or strict then R4 or adjust IGP cost to grantee in the traceroute from R1 to R5 will take the expected path (R1--> R3--> R4 --> R5)

BR

Mohamed Elhariry

[krenjt]

Thank you guys, sorry for replying so late

First i want to say, i did the test on olive not a real router.

The attachment is the traceoption from R4 and show mpls lsp ingress extensive on R1
obviously, R4 received a Path message from R3 and it sent a PathErr to R3.

[mhariry · Accepted solution]

Hi I think it is routing problem could you try to do trace route from R1 to R5 egress IP in the LSP or do show route for the R5 egress IP at R3 itself and see the result

[krenjt]

Hi,thank you very much, you are right. a wrong interface was configured under protocol Isis on r5, so r3 did not establish a adjacency with r5 and r3 chooses r4 as its next hop to r5. As jstar mentioned, r3 sent a patherr to r1. Thanks.