Date: Tue, 02 Nov 2004 11:38:36 -0800 From: Justin Bennett <justin@z-axis.com> To: FreeBSD Hackers <freebsd-hackers@freebsd.org> Subject: ipfw pipes: theoretical speed vs. reality Message-ID: <4187E23C.7000900@z-axis.com>
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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 All, I have recently been setting up pipes to shape bandwidth on our local net. However, unless I am missing something, the TCP overhead seems quite large. If I configure the following pipe: $IPFW pipe 1 config bw 64Kbit/s $IPFW add 31 pipe 1 ip from 192.168.0.1/24 to any $IPFW add 32 pipe 1 ip from any to 192.168.0.1/24 The run traffic from my machine (192.168.0.2) through it, I get less than half the expected bandwidth (3.9KB/s). I tried another test with a 512Kbit/s pipe, and got around 30KB/s. I know on most ATM/FR lines, you can expect about 10% overhead, but 50% seems high. When I remove the pipe, my T1 comes back to life, and I can pull the same data at 160+KB/s. Am I missing something? Thanks, Justin -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.5 (MingW32) iD8DBQFBh+I8lNUG+Ne1CZMRAl95AJ973J3YiUIStcyJ5c5gM+i2lrebTACfUE83 4V9bl8bR9GxjHsKqL764hJk= =gc51 -----END PGP SIGNATURE-----
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