M2PA Alignment Question
"Davidson, Mark" <[email protected]>
| Newsgroups | gmane.ietf.sigtran |
|---|---|
| Message-ID | <[email protected]> |
The following text regarding LSR suggests that M2PA is expected to
behave like Q.703, entering the Aligned-Ready state (with T1 running)
after Proving:
The Link Status Ready message replaces the FISU of MTP2 that is
sent
at the end of the proving period. The Link Status Ready message is
used to verify that both ends have completed proving. When M2PA
starts timer T1, it SHALL send a Link Status Ready message to its
peer in the case where MTP2 would send a FISU after proving is
complete. If the Link Status Ready message is sent, then M2PA MAY
send additional Link Status Ready messages while timer T1 is
running.
These Link Status Ready messages are sent on the Link Status
stream.
But the latter part of Figure 12 of RFC shows the right side going
directly
from Proving to In-Service. Is there some text that describes/requires
this behavior? I understand there is a problem if you don't do this,
as you need another LSR to move from Aligned-Ready to In-Service. But
M2PA only requires one to be sent (even with repeated LSRs, once T1
is stopped on the left, the right side could get stuck).
MTP3 M2PA SCTP SCTP M2PA MTP3
---- ---- ---- ---- ---- ----
. . . . . .
. Start timer T3 . . .
. Link Status Proving . . .
. ------------------------------------> .
. . . . . .
. . . Link Status Proving .
. <------------------------------------ .
. . . . . .
. Stop timer T3 . . .
. . . . . .
. Start timer T4 . . .
. Link Status Proving . . .
. ------------------------------------> .
. ------------------------------------> .
. ------------------------------------> .
. ------------------------------------> .
. ------------------------------------> .
. ------------------------------------> .
. . . . . .
. Timer T4 expires . . .
. . . . . .
Send Link Status Ready (one or more) and wait for the remote end
to complete its proving period.
. . . . . .
. Start timer T1 . . .
. . . . . .
. Link Status Ready . . .
. ------------------------------------> .
. . . . . .
. . . . . .
. . . Link Status Ready .
. <------------------------------------ .
. . . . . .
. Stop timer T1 . . .
. . . . . .
In Service . . In Service
<------------ . . ------------>
. . . . . .
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