Subject: [mpls] Question on draft-boutros-pwe3-mpls-tp-mac-wd-01

From: Greg Mirsky <[email-masked]>
Date: Tue, 17 May 2011 21:44:11 -0700

Dear Authors and All,
I have a question to the document presented. The question is related to
format of PW OAM message as defined in draft-ietf-pwe3-static-pw-status-03:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |0 0 0 1|Version|   Reserved    | 0xZZ PW OAM Message           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Refresh Timer         |  TLV Length   |A|   Flags     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                            TLVs                               ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

TLV Length is 8 bits long and thus combined length of PW OAM TLVs can be
only 255 bytes long. That is sufficient for signalling PW Status message.
But the limit might force to send multiple PW OAM messages if the list of
specific MAC addresses to withdraw grows too long. Perhaps the format of PW
OAM message might be changed to use ACH TLV per RFC 5586, have Refresh Timer
and PW OAM Flag TLVs.

Regards,
Greg