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Stewart, Carlos and all, I understand the concerns with the 16-bit space for sequence numbers and the skip-zero approach taken by RFC 4385 (presumably, for compatibility with the early
Martini drafts that have already been implemented). And it was quite convenient to turn off sequencing in PWs simply by setting SN to zero, (The TDM PWs that MUST use sequence numbers because they MUST detect lost packets and compensate the lost payload use the entire 16-bit SN space). But I think that the draft should clearly articulate these considerations and also provide a definition of in-order and out-of-order packets. I have not found
any of these things in the draft – did I miss something? Regards, Sasha Office: +972-39266302 Cell: +972-549266302 Email: Alexander.Vainshtein@xxxxxxxxxxx From: rtg-dir <rtg-dir-bounces@xxxxxxxx>
On Behalf Of Stewart Bryant
Hi Carlos Thanks for the review. Just picking up a couple of points at this stage, The PCW only supports a 16bit sequence number and it has the skip zero auto-signalling of active S/N feature. This was a problem for DetNet because: - We were worried about S/N rollover frequency in some applications and so we wanted the option of a larger S/N. - We wanted to have the option to propagate the S/N from the payload to the transport to simplify the implementation in some cases. These applications have a non-skip zero S/N. Skip zero is an irritation to implement and we should probably
have signalled in in PWs. As you note in is only a preferred design for PWs, DetNet is not constrained by that and there were good reasons to adopt this alternate approach,
I think it just needs a “for example” and I think that it needs to be made clear that the design is not restricted to a single method of establishing an LSP nor to the characteristics and constraints that go with those LSPs.
Work has started on OAM, for example draft-mirsky-detnet-mpls-oam-00 The OAM for DetNet will be more complex than the OAM for a classical P2P or P2MP LSP (or PW) because of the PREOF function. There is nothing in the data plane that precludes us using on of the existing OAM indicators (GAL or 0001 ACH),
but I think that it is important to thing through the subtleties. Thus I think it is OK to make progress on the elements of the data plane that we can nail down, and leave. The OAM as follow-up work.
This will get picked up on the next resin as part of the Nits check. Best regards Stewart ___________________________________________________________________________ This e-mail message is intended for the recipient only and contains information which is CONFIDENTIAL and which may be proprietary to ECI Telecom. If you have received this transmission in error, please inform us by e-mail, phone or fax, and then delete the original and all copies thereof. ___________________________________________________________________________ |
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