Messages in this thread | | | From | Alan Cox <> | Subject | Re: IP: optimize as a router not host | Date | Tue, 19 Mar 1996 11:10:23 +0000 (GMT) |
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> Umm, yes of course. But selective reject still has advantages. For > instance, the receiver can tell the sender which range(s) of bytes it's > missing, whereas with fast retransmit the sender has to remember the packet > boundaries.
The sender already knows these as it has the packets handy for retransmission. The BSD one simply spots 3 repeated ack values in a row and uses that.
> If more than one packet in that sequence is missing, fast retransmit fails > -- you don't know which packet got lost, you have to wait for the ack, i.e. > at least one round trip delay for each hole. Selective reject would give > you one round trip time total.
Quite probably.
> The rule of thumb seems to be that with more than about 10..25% packet > loss, TCP just doesn't work very well (or not at all, if you want to send > big files). IMHO, selective reject would increase that number somewhat.
Ask a mathematician. Certainly at 40% loss tcp becomes a bit of a joke.
Alan
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