The MPLS-OPS Archive

[Vishal M <vishal_study@yahoo.com>]

Hello,

According to RFC 3036 Appendix A.1.2 (Receive Label
Mapping), if a LSR receives duplicate Label Mapping
from the peer (i.e. same fec and label again), it
should remove the label from the forwarding use.

             RtrX ---LDP----- Cisco GSR

Using RtrX, I advertise duplicate label mapping to the
adjacent Cisco GSR (IOS 12.0(14)ST). I observe that
Cisco accepts the duplicate Label Mapping. 

It doesn't tear down the existing mapping from its
tables (atleast "show mpls ldp bindings" still
displays the binding).

I turned on the debugs at cisco (attached below) and
notice that it does detect the duplicate binding but
doesn't take any (apparant) action.

Has someone noticed this and could someone please
comment on the behavior.

Thanks for your time,

Regards,
Vishal.

cisco debug log for FEC: 99.99.12.12/32
==============================================
006889: 1d04h: ldp: Rcvd label mapping msg from
172.19.78.85:0 (pp 0x64E8E138)
006890: 1d04h: tagcon: tibent(99.99.12.12/32):
created; remote label learned
006891: 1d04h: tagcon: tibent(99.99.12.12/32): label
65544 from 172.19.78.85:0 added

006892: 1d04h: ldp: Rcvd label mapping msg from
172.19.78.85:0 (pp 0x64E8E138)
006893: 1d04h: tagcon: tibent(99.99.12.12/32): label
65544 from 172.19.78.85:0 added



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