RE: A Question about "Inter Packet Gap and SOP Lane alignment"
Maybe we should reconsider the use of /A/ for alignment. We don't
really need to use a special character for lane alignment. We could
just as well perform the alignment on the IDLE->DATA transition at
the start of each packet.
All of this /A/K/R/O/ stuff during IDLE is getting out of hand.
We would be better off with simpler rules for IDLE, like a randomized
sequence of Ks and Rs.
In fact, if we did the alignment based on the transition from
lane[0:3]=IDLE to (lane[0]=SOP & lane[1:3]=data), then we wouldn't
need to maintain columns of Ks and Rs during IDLE. We would just need
to send a complete column of R once during IPG, for instance, on the
column immediately following the T. IDLE could be random per-lane Ks
and Rs at all other times.
The IDLE insert/delete rules would remain unchanged.
We don't really need to be aligned until there is a packet to receive,
and the first packet that a receiver gets can be used to establish the
lane alignment. If a receiver looses alignment, it will re-establish
the alignment at the next start of packet.
Howard Frazier
Cisco Systems, Inc.