North American Network Operators Group|
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Re: Why the temptation for dial users to crank back rwin/mtu?
> It's always been my belief that the 576 values were generated by hosts > that didn't support Path MTU discovery and wanted to be conservative > and avoid fragmentation. Fair enough.. .... > apparently there's some performance value in this (at least to the .... > > MTU - at least this makes a little bit of sense.. If they're doing > HTTP/1.0 stuff with parallel connections then a smaller MTU is going > to make that parallelization latency much more effective and perceived > performance will go up some.. it doesn't impact full document > retrieval time though (at least not positively!).. are dial links > really lossy enough that chopping the segment size to 1/3 is a big win > in retransmit time or are the win95/98 stacks really braindead enough > that they don't do pmtud so are just trying to dodge fragmentation? I > found it really odd that  which I use all the time to track > features in a myriad of shipped OS's actually has a blank entry for > pmtud on both of those (neither yes nor no..) This is discussed in depth in RFC1191 and W. Richard Stevens' book "TCP/IP Illustrated Volume 1" (see page 29-31). Aron