LDP Neighbor Problem

[shahzad.adnan]

This day  found there is an issue between the our 2 LDP Neighbors Switches.LDP neighbor router id is continues flapping for few secs. There is some TCP Sync problem the you can see as following.

P2#sh tcp brief all
TCB       Local Address               Foreign Address             (state)
55B7A194  10.13.130.4.32702           10.13.130.2.179              SYNSENT
53D7D134  0.0.0.0.179                 10.13.130.2.*                LISTEN

Here your can see neighbor router id is missing.

P2#sh mpls ldp discovery
 Local LDP Identifier:
    10.13.130.4:0
    Discovery Sources:
    Interfaces:
        TenGigabitEthernet2/7 (ldp): xmit
        TenGigabitEthernet7/8 (ldp): xmit/recv
            LDP Id: 10.13.130.3:0

Here you can see route id come back.

P2#sh mpls ldp discovery
 Local LDP Identifier:
    10.13.130.4:0
    Discovery Sources:
    Interfaces:
        TenGigabitEthernet2/7 (ldp): xmit/recv
            LDP Id: 10.13.130.2:0
        TenGigabitEthernet7/8 (ldp): xmit/recv
            LDP Id: 10.13.130.3:0

Following is the detail of Neighbor discovery.

P2#sh mpls ldp discovery Detail
 Local LDP Identifier:
    10.13.130.4:0
    Discovery Sources:
    Interfaces:
        TenGigabitEthernet2/7 (ldp): xmit
            Enabled: Interface config
            Hello interval: 5000 ms; Transport IP addr: 10.13.130.4
            Clients: IPv4, mLDP
        TenGigabitEthernet7/8 (ldp): xmit/recv
            Enabled: Interface config
            Hello interval: 5000 ms; Transport IP addr: 10.13.130.4
            LDP Id: 10.13.130.3:0
              Src IP addr: 10.13.131.17; Transport IP addr: 10.13.130.3
              Hold time: 15 sec; Proposed local/peer: 15/15 sec
              Reachable via 10.13.130.3/32
              Password: not required, none, in use
            Clients: IPv4, mLDP

The is no problem in route as route exist in the routing table.

OSPF is running and route also exist in the routing table.

P2#sh ip route ospf

Gateway of last resort is not set

      1.0.0.0/24 is subnetted, 1 subnets
O        1.1.1.0 [110/11] via 10.13.131.13, 05:27:20, TenGigabitEthernet9/7
      10.0.0.0/8 is variably subnetted, 28 subnets, 3 masks
O        10.13.130.1/32
           [110/2] via 10.13.131.13, 05:27:20, TenGigabitEthernet9/7
O        10.13.130.2/32
           [110/2] via 10.13.131.29, 05:27:16, TenGigabitEthernet2/7

Details of LDP Parameters are as following.

P2#sh mpls ldp parameters
LDP Feature Set Manager: State Initialized
  LDP features:
    Basic
    IP-over-MPLS
    TDP
    IGP-Sync
Protocol version: 1
Session hold time: 180 sec; keep alive interval: 60 sec
Discovery hello: holdtime: 15 sec; interval: 5 sec
Discovery targeted hello: holdtime: 90 sec; interval: 10 sec
Accepting targeted hellos
Downstream on Demand max hop count: 255
LDP for targeted sessions
LDP initial/maximum backoff: 15/120 sec
LDP loop detection: off

T1-SOC-Co2#sh mpls ldp parameters
Protocol version: 1
Session hold time: 180 sec; keep alive interval: 60 sec
Discovery hello: holdtime: 15 sec; interval: 5 sec
Discovery targeted hello: holdtime: 90 sec; interval: 10 sec
Accepting targeted hellos
Downstream on Demand max hop count: 255
LDP for targeted sessions
LDP initial/maximum backoff: 15/120 sec
LDP loop detection: off

Can someone help to troubleshoot the issue. What can be the reason?

[Dan Lukes · Accepted solution]

You should not ask in random communities unrelated to the topic of question. If you wish for valuable response ...

I moved it to Other Network Infrastructure Subjects to increase your chances. Unfortunately, you disclosed no product you are speaking of nor the firmware version so I'm unsure it will help so much.

[Dan Lukes]

Glad to hear my comment has solved the issue, although I'm surprised a lot ...

[shahzad.adnan]

Thanks for it, We are using 6500 on both switches. For P1 we using IOS ADVIPSERVICESK9_WAN-M  Version 12.2(33)SXH5  and for P2 using  ADVENTERPRISEK9-M), Version 15.1(2)SY4a.