MPLS LDP neighbor not coming up

[yagnesh chauhan]

Hello Team,

I had working LDP session stopped suddenly & not able to find the exact root cause as Cisco & service provider both are saying it's not their issue.

It was between 2 WS-C6506-E & LDP session stopped suddenly , my other traffic over link is working fine (isis , ssh , ip traffic).

Any suggestion is welcomed.

Router A - 172.16.20.133 - Gi2/5 <===> Gi2/2 - 172.16.20.134 - Router B

A#show mpls ldp neighbor Gi2/5

A#
A#show mpls ldp discovery | i 2/5
GigabitEthernet2/5 (ldp): xmit

A#ping 224.0.0.2

Type escape sequence to abort.
Sending 1, 100-byte ICMP Echos to 224.0.0.2, timeout is 2 seconds:
Reply to request 0 from 172.16.20.134, 160 ms
A#

B#show mpls ldp discovery | i 2/2
GigabitEthernet2/2 (ldp): xmit/recv
B#ping 224.0.0.2

Type escape sequence to abort.
Sending 1, 100-byte ICMP Echos to 224.0.0.2, timeout is 2 seconds:
B#
B#show mpls ldp neighbor Gi2/2

B#

[Nagendra Kumar Nainar]

Hi Yagnesh,

Based on your ping test, it appears that the multicats pakcet destinated to 224.0.0.2 (and so the LDP hello packets) from B is not reaching A while the other way is working fine. As you can observe LDP hellos are xmit/recv on B while just xmit (and not recv) on A.

I assume there is some misprogramming on the LC/SUP causing packet destinated to 224.0.0.2 to be dropped. Depending on the linecard (DFC/PFC), we may need to check the programming. Can you share the output of "show module" from both the boxes?.

-Nagendra

[yagnesh chauhan]

Hello Nagendra,

Thank for acknowledgement ; below is the output , let me know if you need more info 

A#

show module
Mod Ports Card Type Model Serial No.
--- ----- -------------------------------------- ------------------ -----------
1 24 CEF720 24 port 1000mb SFP WS-X6724-SFP 
2 48 CEF720 48 port 10/100/1000mb Ethernet WS-X6748-GE-TX 
3 8 CEF720 8 port 10GE with DFC WS-X6708-10GE 
5 5 Supervisor Engine 720 10GE (Active) VS-S720-10G 

Mod MAC addresses Hw Fw Sw Status
--- ---------------------------------- ------ ------------ ------------ -------
1 5475.d0bb.b7e0 to 5475.d0bb.b7f7 4.3 12.2(18r)S1 12.2(33)SXI7 Ok
2 0017.951a.b5c0 to 0017.951a.b5ef 2.3 12.2(14r)S5 12.2(33)SXI7 Ok
3 0023.5e7f.2908 to 0023.5e7f.290f 1.6 12.2(18r)S1 12.2(33)SXI7 Ok
5 001e.4a7e.7d30 to 001e.4a7e.7d37 2.1 8.5(4) 12.2(33)SXI7 Ok

Mod Sub-Module Model Serial Hw Status
---- --------------------------- ------------------ ----------- ------- -------
1 Distributed Forwarding Card WS-F6700-DFC3C SAL1304H697 1.2 Ok
2 Distributed Forwarding Card WS-F6700-DFC3C SAL1224TNVQ 1.0 Ok
3 Distributed Forwarding Card WS-F6700-DFC3C SAL12437E9N 1.0 Ok
5 Policy Feature Card 3 VS-F6K-PFC3C SAL1304H2PL 1.0 Ok
5 MSFC3 Daughterboard VS-F6K-MSFC3 SAL1302G1J6 1.0 Ok

Mod Online Diag Status
---- -------------------
1 Pass
2 Pass
3 Pass
5 Pass

B#show module
Mod Ports Card Type Model Serial No.
--- ----- -------------------------------------- ------------------ -----------
1 48 48-port 10/100/1000 RJ45 EtherModule WS-X6148A-GE-TX 
2 24 CEF720 24 port 1000mb SFP WS-X6724-SFP 
5 2 Supervisor Engine 720 (Active) WS-SUP720-3B 

Mod MAC addresses Hw Fw Sw Status
--- ---------------------------------- ------ ------------ ------------ -------
1 0018.ba3f.07a0 to 0018.ba3f.07cf 1.5 8.4(1) 12.2(33)SXI7 Ok
2 68ef.bd09.7c24 to 68ef.bd09.7c3b 4.6 12.2(18r)S1 12.2(33)SXI7 Ok
5 0013.c43b.02ec to 0013.c43b.02ef 5.2 8.5(2) 12.2(33)SXI7 Ok

Mod Sub-Module Model Serial Hw Status
---- --------------------------- ------------------ ----------- ------- -------
2 Centralized Forwarding Card WS-F6700-CFC SAL190281N5 4.2 Ok
5 Policy Feature Card 3 WS-F6K-PFC3B SAL1021PC6N 2.3 Ok
5 MSFC3 Daughterboard WS-SUP720 SAL1020NMFZ 2.5 Ok

Mod Online Diag Status
---- -------------------
1 Pass
2 Pass
5 Pass

[Nagendra Kumar Nainar · Accepted solution]

Hi,

On B the LC is PFC based while on A it is DFC based. Do you have any otehr neighbors on A or B?.

I assume Router A's LC in module 2 might have some programming issue causing it to drop 224.0.0.2. One option is to either move the connection to a different line card or to try reload line card in module 2 and see if it helps.

-Nagendra

[yagnesh chauhan]

Thanks ,

It was working previously but suddenly stopped :( , will try to reload A end line card.