Actually PW stitching can be implemented entirely using
existing pseudowire
signaling procedures (using LDP or L2TP) without any new
protocol or extension.
The signaling protocol is not an issue.
Hi Wei,
I respectfully disagree. The fact that we have a signaling protocol to set up single PW segments doesn't mean that it is clear how to establish multi-segment PWs. E.g.
- Are segments set up in a random order or is there a need for a certain sequence of message?
- Is it necessary to use the same values for Interface Parameters on each segment?
- Is VCCV used on single segments or end-to-end? If the latter, do intermediate points monitor or do they blindly forward the packets?
- In case a segment goes down, are alarm signals sent to the end-points of the multi-segment PW or is the error handled locally?
All these, and probably more, need to be specified. On the other hand, if we decide that a multi-segment PW is essentially an LSP that can be set up with RSVP-TE, the RSVP-TE spec provides most of the answers.
Peter
With regard to PW stitching, this working group probably
should focus on the
operational issues with regard to PW stitching, such as
whether Attachment
Circuit interworking is needed at the stitching point, how to
interwork between
different PSN types, sequencing, multi-hop VCCV, Inter-AS
considerations and
other network management subjects.
---Wei