The MPLS WG Archive

Cell Relay Retreat>MPLS WG Archive>month:2005-Dec> msg00047



[Date Prev][Date Next][Thread Prev][Thread Next]  
  [Date Index][Thread Index][Author Index][Subject Index]

[mpls] draft-weilian-mpls-fast-reroute-ext-00

  • From: Alia Atlas <akatlas@gmail.com>
  • Date: Wed, 21 Dec 2005 15:56:21 -0800
  • DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com;h=received:message-id:date:from:to:subject:mime-version:content-type:content-transfer-encoding:content-disposition;b=Xrk7emMi94aOju6MmBs+4qYdSSiXcFQBz0l3yLduBxeOhMHdcba/kZLmj8AliMTrQPuBPtTajPWOVsiMe7JCry9PV2zN/vZXJY+YvkovIQFSr9tP48PlhaKpjn9PzJQr2HHQ4KbXy3h3O8FXqtsEE0CkzqDOnvFG/b9vutuyWf8=
  • X-MIME-Autoconverted: from quoted-printable to 8bit by cell.onecall.net id jBLNnbH17525

On reading the introduction of this draft, I am unclear about the
motivation and problem that it is trying to solve.  The draft says:

"However, for N:1 backup, after the protected tunnel switches to the
backup tunnel, the protocol state should still be refreshed through
sending protocol messages of the protected tunnel along the path of
backup tunnel. Once FRR switchover occurs, abundant Refresh messages
of the protected tunnel are transmitted along the path of backup
tunnel, intermediate and tail nodes of the backup tunnel will allocate
abundant useless labels."

As I understand the bypass tunnel mechanism, the Refresh messages for
the protected tunnels are sent to the merge node via the backup
tunnel; this means that the Refresh messages are encapsulated and not
seen by the intermediate nodes of the backup tunnel.
When the refresh message is seen by the tail node of the backup tunnel
(which is the MP), the MP will look-up the state and label assigned to
the associated protected LSP and refresh the state and provide the
label back.

I don't see that there is any allocation of useless labels.  Could you
clarify an example where this happens?  In particular, could you pull
the problem from RFC4090?

Thanks,
Alia

_______________________________________________
mpls mailing list
mpls@lists.ietf.org
https://www1.ietf.org/mailman/listinfo/mpls