Thomas Kunz
Systems and Computer Engineering
22
Snoop: Description of Protocol
nprocessing
packets from FH
–new
packet in the normal TCP sequence:
ncache
and forward to MH
–packet
out-of sequence and cached earlier:
nsequence
number > last ack from MH: packet probably lost, forward it again
notherwise,
packet already received at MH, so drop
–but:
original ACK could have been lost, so fake ACK again
–packet
out-of sequence and not cached yet:
npacket either lost earlier due to congestion or
delivered out-of-order: cache
packet and mark as retransmitted, forward to MH