Re: [dcp] sequence numbers on resend

["Patrick R. McManus" <mcmanus@ducksong.com>]

more thoughts on resending requests - what about requests with data?
Warning, this scenario may not be fully baked - I've just started
toying with it.

the state diagram says you only count that data once (requests outside
of LISTENING are ignored)..


t0: xmit A->B Req    SN=0 with data
t3: xmit A->B Req    SN=1 with data

t5: rcv  A->B Req    SN=1 with data
t5: xmit B->A Resp   SN=0 ack=1 vector=0,192
t6: rcv  A->B Req    SN=0 with data (dropped as we're in APP-ACCEPT)

t7: rcv  B->A Resp   SN=0 ack=1 vector=0,192

..

so the client (A) now has only 1 of 2 xmitted packets
ack'd.. this is fine, as it was true when B generated the ack
vector.. however new ack vectors at times > 6 will still represent
sn=0 as unreceived (which is untrue) and will impinge on A's cwnd for
a while.

if A retransmits with the same isn (because it's the same data he is
only expecting one ack bit for) this problem goes away. 


-Patrick

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