correlation between SDP status and T-LDP

[moods]

Hi,

i am doing some interop testing between ALU 7750 and third party. I am testing VPLS and the life is good until i do a deletion and than re-addition of VPLS configuration on third party router.

Deletion

- Router x send Label withdraw/release message to ALU
- SDP is operationally down as there is no egress label. Ingress label is still assigned
- T-LDP session stays up

When doing a re-addition of that VPLS service on third party router, that router sends label mapping message to ALU SDP gets operationally up.

Here comes the problem. ALU does not (re)send label mapping message and third party router does not have an egress label for that service.

What are my options?

thanks for help

[mivens]

Have you tested if flapping the LDP session is a workaround?

If so, does the remote router support LDP graceful restart?

I know of another vendor with a slightly similar interop issue with epipes/psuedowire services who recommended a command on their kit "l2vpn neighbor all ldp flap" as a workaround that automatically flaps the LDP session when the first PWE is configured.

[moods]

Hi,

Yes flapping LDP session is a workaround, but the remote router does not supports LDP GR.

Why ALU does not resend label with label mapping message although i shutdown a.) complete service b.) shutdown mesh:sdp ?

thanks for explanation

[mivens]

Off the top of my head, the question might also be whether the remote end sends a label request.

What would be interesting would be to compare the behaviour when there's an Alcatel at each end.

I know there are LDP interop issues with devices not sending label mapping messages that the IETF are trying to fix via updated standards recommendations. See for example the requirements section at https://www.ietf.org/archive/id/draft-b ... est-01.txt.

Other vendors have partial workarounds that involve automatically flapping the LDP session (which might not work in your case if the remote end doesn't support GR).