RoE header and mapper thoughts: sequence numbering..

[Jouni Korhonen <jouni.korhonen@xxxxxxxxxxxx>]

Folks,

I have been thinking about the RoE header and a need for sequence number in it. There would be two uses for it, at least initially. First, we need that in the mapper to regenerate the CPRI HFN and BFN fields. Second, it would allow us to detect possible lost packet. Maybe there could be a case as well for reordering? Anyway, in the RoE example I had I reserved 16 bits for the sequence number space. That is enough to number >10ms worth of CPRI BFs and HFs for the mapper purposes. However, 16 bits is not enough to explicitly transport CPRI HFN and BFN information (that's 20bits worth data). Anyway, generating those missing 4 bits is not imho a big deal.. we already do that routinely with ESP etc (64bits extended sequence number but only transport low order 32bits). Again I am assuming the sequence number space is unique between two endpoints (whether mechanism we use to determine endpoints).

Any thoughts?

- Jouni

-- 
Jouni Korhonen, Ph.D, Associate Technical Director
CTO Office, Networking, Broadcom Corporation
O: +1-408-922-8135,  M: +1-408-391-7160