Tal I think the optional offset is the beginning of the 1588 payload (i.e., below any Ethernet or UDP/IP headers).
Now that I think of it, using this offset we could handle the generic CF as well ! FCS retention refers to RFC4720 - where the Ethernet FCS is retained in an Ethernet PW (which is not done in the standard RFC 4448). In any case, any time one goes over an Ethernet link - even if only between LSRs, the FCS needs to be recomputed before putting an Ethernet frame on an Ethernet link. This FCS is NOT the FCS of the original 1588oEthernet or 1588oUDP/IPoEthernet frame. Y(J)S From: [email protected] [mailto:[email protected]] On Behalf Of Tal Mizrahi Sent: Friday, April 01, 2011 08:06 To: Shahram Davari; [email protected] Subject: [TICTOC] Questions about draft-ietf-tictoc-1588overmpls Hi Shahram, After a deeper review of your presentation, a couple of questions: - The optional OFFSET: the draft should specify the start point of the offset. I assume this would be the beginning of the MPLS stack, since the MPLS layer is not aware of the length of lower layer headers, right? - The PPT (and similarly the draft) says "Ethernet FCS must be calculated at every LSR" - this refers to the FCS of the outer Ethernet packet, right? (Since the next line says "FCS retention must not be used"). It is worth to clarify in the draft. Thanks, Tal.
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