The MPLS WG Archive

[Vijayanand C <vijayc@ctd.hcltech.com>]

Hello all,
I have a question regarding label distribution in CR LDP.

Assume that a CR LSP is established and at an intermediate LSR a Next Hop
change occurs. When the intermeditate LSR requests for and gets a mapping
from the New Next hop it will propagate the mapping upstream since the HC/PV
values have changed(according to procedures in RFC3036 which is applicable
for CR LDP also). This mapping is, strictly speaking, an unsolicited
mapping. So, is this behaviour of propagating the mapping upstream because
the HC /PV attributes differ from the values in the previous mapping,
correct for Dod Ordered control .

If so, what will be the request message ID in the mapping message ?. In CR
LDP, the request message ID TLV is mandatory for the mapping message.  Would
it be correct to use the request ID of the last request received from
upstream, for which mapping was already sent. This strategy will prevent the
upstream from reusing that message ID indefinitly. 

Please clarify and correct me if I am wrong.

Thanks in advance,
Regards,
Vijay