> Second, I've been considering writing up a new type of SACK option.
> The specific idea I had was to make one which I jokingly call a CRACK
> (CoRruption ACK) for specific use with wireless. Receivers should, in
> principle, be able to detect packets with failed checksum and send
> back a CRACK indicating to the sender that a packet has been dropped,
> but it is not a sign of congestion -- retransmit the packet but don't
> reduce cwnd.
We've looked at this concept from time to time over the years. One issue you
have to deal with is that if the checksum fails, can you trust the fields in
the packet you use to identify the sender of the packet. There is risk
associated with assuming that you can and that risk is different for different
types of links. (For example, with an older implementation of our spacelink
"MAC", errors tended to occur towards the end of packets because of the way our
forward error correction worked. Our newer encoding is much better at
correcting errors but encoding includes spreading the bits around so errors
which can't be corrected can be anywhere in the packet.)
John Border
Hughes Network Systems
This archive was generated by hypermail 2b29 : Mon Jan 28 2002 - 09:12:19 EST