The MPLS WG Archive

[Katta Sambasiva Rao <KattaSR@netbrahma.com>]

Hi,
I have a doubt in Route pinning of CR-LDP.

Suppose an LSP is pinned to a route. The draft says if there is a new better
route for the established LSP, it should not be considered for pinned LSP.

But if the route becomes completely un-available (say next-hop) failed and
an alternate path which meets LSP requirements exist, what action needs to
be taken. Does the CR-LSP should be teared down as pinning condition cant be
met or the alternate path which meets the requirements should be considered
to set-up LSP from failed point considering the view point that pinning was
for avoiding disruption of services.

problem explained with example: 

A,B,C,D is Explicit route specified, with C as loose hop.
Suppose LSP is set-up with nodes A,B,Z,C,D and pinned.
Now node Z failed, but there is alternate path B,X,C which meets LSP
requirements.
Now what action B should take when it detects it cant reach Z. Should it try
to change LSP path as A,B,X,C,D or tear down the LSP.

If it is implemetation choice, please give your analysis of pros and cons of
each approach.

Thanks in advance.

regards,
Katta