Date: Wed, 10 Apr 2002 20:13:38 -0400 From: "ipver4" <ipver4@hotmail.com> To: <paul+usenet@w6yx.stanford.edu> Cc: <net@freebsd.org> Subject: Re: TCP Timestamp option? Message-ID: <OE29hkKoCoj6ULO51Sh0000d849@hotmail.com> References: <a91v6e$1f3v$1@hairball.treehouse.napa.ca.us>
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Thanks for the explanation. It seems since version 4.4 that kernel net.inet.tcp.rfc1323 is set to 1 by default, thus causing all the TCP connections to use the RFC1323 extension. The effects are: 1. bigger TCP header. 2. more processing time at sending and receiving hosts. 3. VJ TCP/IP header compression algorithm does not compress most of the time. I am not sure turning on the RFC1323 support on by default is such a good idea. > The TCP timestamp option is used to obtain better round-trip time > estimates than can be obtained without, and these estimates turn out > to be important in networks with large bandwidth*delay products. > > Timestamps in the timestamp option also cycle much more slowly than > sequence numbers on an active high-speed connection and can thus be used > to detect and discard old duplicate packets with apparently valid sequence > numbers. > > RFC 1323 explains the details. > -- > G. Paul Ziemba paul@w6yx.stanford.edu > FreeBSD unix: > 11:06AM up 16 days, 14 mins, 7 users, load averages: 0.03, 0.03, 0.00 > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-net" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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