The MPLS-OPS Archive

["Vinaychandra A V S" <vinaychandra.sham@wipro.com>]

Rohit,

The problem you have described will not occur, as addresses in ERO will
usually denote the outgoing interfaces.

After prefixing the detour ERO, the detour path ERO originating from B
will look like this:
interface B-E of B
interface E-F of E
interface F-D of F
interface D-G of D

Even if there are more than 1 entries in the ERO, belonging to the same
node, the ERO processing rules laid out in RFC 3209 will take care of
ignoring the redundant ones.

Hope this helps...

Regards,
Vinay.

-----Original Message-----
From: Rohit Mediratta [mailto:rohit_medi@yahoo.com] 
Sent: Friday, May 23, 2003 4:45 AM
To: mpls-ops@mplsrc.com
Subject: [MPLS-OPS]: Fast reroute extensions to RSVP-TE for LSP Tunnels

Hi, 

Attached is a paragraph from "Fast reroute Extensions
to RSVP-TE for LSP Tunnels" Sec 6.3

- The PLR MUST generate an EXPLICIT_ROUTE object
toward the egress.First, the PLR must remove all
sub-objects preceding the first address belonging to
the Merge Point.  Then the PLR SHOULD add sub-objects
corresponding to the desired backup path between the 
PLR and the MP.

 I have this setup

   A---B---C---D--G
       |       |
       E-------F

If i have a Fast reroute LSP setup between Router A
and Router G with
every interface on the primary path explicitly defined
in the hop list. The PLR (Router B) would signal a
Detour path to Router D via E and F. 
It seems to me from the paragraph attached above, that
Router B should not remove the sub-object for the
interface on Router D towards C. As that interface
shall be "belonging to the merge point".

However if we do that the ERO for the detour PATH will
have the following ERO
interface B-E
interface E-F
interface F-D
interface D-C  <----
interface D-G

This will never be setup.

Am i interpreting the draft incorrectly ?

thanks,
rohit


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