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Date: Mon, 06 Nov 2000 19:44:57 -0800
From: Jordan Mendelson <jordy@napster.com>
Organization: Napster, Inc.
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To: davem@redhat.com, kuznet@ms2.inr.ac.ru, ak@muc.de, netdev@oss.sgi.com,
        linux-kernel@vger.kernel.org
Subject: Re: Poor TCP Performance 2.4.0-10 <-> Win98 SE PPP
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Jordan Mendelson wrote:
> 
> We are seeing a performance slowdown between Windows PPP users and
> servers running 2.4.0-test10. Attached is a tcpdump log of the
> connection. The machines is without TCP ECN support. The Windows machine
> is running Windows 98 SE 4.10.2222 A dialed up over PPP w/ TCP header
> compression. The Linux machine is connected directly to the Internet via
> a 6509. There is a possibility that we are hitting a bandwidth cap on
> outgoing traffic.


Just some updates. This problem does not appear to happen under 2.2.16.
The dump for 2.2.16 is almost the same except we send an mss back of 536
and not 1460 (remote mtu vs local mtu).

Here is the head of a tcpdump with the same client, but this time with a
2.2.16 machine instead of a 2.4.0-test10 machine:

19:26:23.593114 eth0 < 209.179.248.69.1260 > 64.124.41.136.8888: S
5061245:5061245(0) win 8192 <mss 536,nop,nop,sackOK> (DF)
19:26:23.593237 eth0 > 64.124.41.136.8888 > 209.179.248.69.1260: S
119520695:119520695(0) ack 5061246 win 32696 <mss 536,nop,nop,sackOK>
(DF)
19:26:23.824394 eth0 < 209.179.248.69.1260 > 64.124.41.136.8888: .
1:1(0) ack 1 win 65280 (DF)
19:26:23.824398 eth0 < 209.179.248.69.1260 > 64.124.41.136.8888: .
1:1(0) ack 1 win 8576 (DF)
19:26:23.825249 eth0 < 209.179.248.69.1260 > 64.124.41.136.8888: P
1:44(43) ack 1 win 65280 (DF)
19:26:23.825283 eth0 > 64.124.41.136.8888 > 209.179.248.69.1260: .
1:1(0) ack 44 win 32696 (DF)
19:26:25.245845 eth0 > 64.124.41.136.8888 > 209.179.248.69.1260: P
1:21(20) ack 44 win 32696 (DF)
19:26:25.245956 eth0 > 64.124.41.136.8888 > 209.179.248.69.1260: P
21:342(321) ack 44 win 32696 (DF)
19:26:25.466759 eth0 < 209.179.248.69.1260 > 64.124.41.136.8888: .
44:44(0) ack 342 win 64939 (DF)
19:26:25.466792 eth0 > 64.124.41.136.8888 > 209.179.248.69.1260: P
342:878(536) ack 44 win 32696 (DF)
19:26:25.466800 eth0 > 64.124.41.136.8888 > 209.179.248.69.1260: P
878:1401(523) ack 44 win 32696 (DF)
19:26:25.467562 eth0 < 209.179.248.69.1260 > 64.124.41.136.8888: P
44:56(12) ack 342 win 64939 (DF)
19:26:25.480104 eth0 > 64.124.41.136.8888 > 209.179.248.69.1260: .
1401:1401(0) ack 56 win 32696 (DF)
19:26:25.763509 eth0 < 209.179.248.69.1260 > 64.124.41.136.8888: P
56:456(400) ack 878 win 65280 (DF)
19:26:25.766253 eth0 < 209.179.248.69.1260 > 64.124.41.136.8888: .
456:456(0) ack 1401 win 64757 (DF)
19:26:26.070115 eth0 > 64.124.41.136.8888 > 209.179.248.69.1260: .
1401:1401(0) ack 456 win 32296 (DF)
19:26:26.431515 eth0 > 64.124.41.136.8888 > 209.179.248.69.1260: P
1401:1413(12) ack 456 win 32696 (DF)
19:26:26.432141 eth0 > 64.124.41.136.8888 > 209.179.248.69.1260: P
1413:1684(271) ack 456 win 32696 (DF)
19:26:26.657631 eth0 < 209.179.248.69.1260 > 64.124.41.136.8888: .
456:456(0) ack 1684 win 65280 (DF)
19:26:26.657663 eth0 > 64.124.41.136.8888 > 209.179.248.69.1260: P
1684:1817(133) ack 456 win 32696 (DF)
19:26:26.952825 eth0 < 209.179.248.69.1260 > 64.124.41.136.8888: .
456:456(0) ack 1817 win 65147 (DF)
19:26:31.086138 eth0 < 209.179.248.69.1260 > 64.124.41.136.8888: P
456:506(50) ack 1817 win 65147 (DF)

> 18:51:33.282286 eth0 < 209.179.248.69.1238 > 64.124.41.177.8888: S
> 3013389:3013389(0) win 8192 <mss 536,nop,nop,sackOK> (DF)
> 18:51:33.282395 eth0 > 64.124.41.177.8888 > 209.179.248.69.1238: S
> 2198113890:2198113890(0) ack 3013390 win 5840 <mss 1460,nop,nop,sackOK>
> (DF)
> 18:51:33.509532 eth0 < 209.179.248.69.1238 > 64.124.41.177.8888: .
> 1:1(0) ack 1 win 8576 (DF)
> 18:51:33.510360 eth0 < 209.179.248.69.1238 > 64.124.41.177.8888: .
> 1:1(0) ack 1 win 65280 (DF)
> 18:51:33.510416 eth0 < 209.179.248.69.1238 > 64.124.41.177.8888: P
> 1:44(43) ack 1 win 65280 (DF)
> 18:51:33.510457 eth0 > 64.124.41.177.8888 > 209.179.248.69.1238: .
> 1:1(0) ack 44 win 5840 (DF)
> 18:51:33.988330 eth0 > 64.124.41.177.8888 > 209.179.248.69.1238: P
> 1:21(20) ack 44 win 5840 (DF)
> 18:51:33.988474 eth0 > 64.124.41.177.8888 > 209.179.248.69.1238: P
> 21:557(536) ack 44 win 5840 (DF)
> 18:51:36.987336 eth0 > 64.124.41.177.8888 > 209.179.248.69.1238: P
> 1:21(20) ack 44 win 5840 (DF)
> 18:51:37.177772 eth0 < 209.179.248.69.1238 > 64.124.41.177.8888: P
> 44:56(12) ack 21 win 65260 (DF)
> 18:51:37.177794 eth0 > 64.124.41.177.8888 > 209.179.248.69.1238: P
> 21:557(536) ack 44 win 5840 (DF)
> 18:51:37.177806 eth0 > 64.124.41.177.8888 > 209.179.248.69.1238: P
> 557:1093(536) ack 56 win 5840 (DF)
> 18:51:39.845046 eth0 < 209.179.248.69.1238 > 64.124.41.177.8888: P
> 44:456(412) ack 21 win 65260 (DF)
> 18:51:39.845071 eth0 > 64.124.41.177.8888 > 209.179.248.69.1238: .
> 1093:1093(0) ack 456 win 6432 <nop,nop, sack 1 {44:56} > (DF)
> 18:51:43.177329 eth0 > 64.124.41.177.8888 > 209.179.248.69.1238: P
> 21:557(536) ack 456 win 6432 (DF)
> 18:51:43.538219 eth0 < 209.179.248.69.1238 > 64.124.41.177.8888: .
> 456:456(0) ack 557 win 65280 (DF)
> 18:51:43.538275 eth0 > 64.124.41.177.8888 > 209.179.248.69.1238: P
> 557:1093(536) ack 456 win 6432 (DF)
> 18:51:43.538292 eth0 > 64.124.41.177.8888 > 209.179.248.69.1238: P
> 1093:1629(536) ack 456 win 6432 (DF)
> 18:51:55.537346 eth0 > 64.124.41.177.8888 > 209.179.248.69.1238: P
> 557:1093(536) ack 456 win 6432 (DF)
> 18:51:55.841360 eth0 < 209.179.248.69.1238 > 64.124.41.177.8888: .
> 456:456(0) ack 1093 win 65280 (DF)
> 18:51:55.841384 eth0 > 64.124.41.177.8888 > 209.179.248.69.1238: P
> 1093:1629(536) ack 456 win 6432 (DF)
> 18:51:55.841393 eth0 > 64.124.41.177.8888 > 209.179.248.69.1238: P
> 1629:1849(220) ack 456 win 6432 (DF)
> 18:52:19.837335 eth0 > 64.124.41.177.8888 > 209.179.248.69.1238: P
> 1093:1629(536) ack 456 win 6432 (DF)
> 18:52:20.153776 eth0 < 209.179.248.69.1238 > 64.124.41.177.8888: .
> 456:456(0) ack 1629 win 65280 (DF)
> 18:52:20.153803 eth0 > 64.124.41.177.8888 > 209.179.248.69.1238: P
> 1629:1849(220) ack 456 win 6432 (DF)
> 18:53:08.147334 eth0 > 64.124.41.177.8888 > 209.179.248.69.1238: P
> 1629:1849(220) ack 456 win 6432 (DF)
> 18:53:08.475911 eth0 < 209.179.248.69.1238 > 64.124.41.177.8888: .
> 456:456(0) ack 1849 win 65060 (DF)
> 18:53:08.475947 eth0 > 64.124.41.177.8888 > 209.179.248.69.1238: P
> 1849:1871(22) ack 456 win 6432 (DF)
> 18:54:44.467332 eth0 > 64.124.41.177.8888 > 209.179.248.69.1238: P
> 1849:1871(22) ack 456 win 6432 (DF)
> 18:54:44.824187 eth0 < 209.179.248.69.1238 > 64.124.41.177.8888: .
> 456:456(0) ack 1871 win 65038 (DF)
> 18:54:44.824256 eth0 > 64.124.41.177.8888 > 209.179.248.69.1238: P
> 1871:1893(22) ack 456 win 6432 (DF)
> 18:54:55.212750 eth0 < 209.179.248.69.1238 > 64.124.41.177.8888: P
> 456:506(50) ack 1871 win 65038 (DF)
> 18:54:55.212767 eth0 > 64.124.41.177.8888 > 209.179.248.69.1238: .
> 1893:1893(0) ack 506 win 6432 (DF)
> 18:54:55.571337 eth0 > 64.124.41.177.8888 > 209.179.248.69.1238: P
> 1893:2429(536) ack 506 win 6432 (DF)
> 18:54:57.394879 eth0 < 209.179.248.69.1238 > 64.124.41.177.8888: P
> 456:506(50) ack 1871 win 65038 (DF)
> 18:54:57.394894 eth0 > 64.124.41.177.8888 > 209.179.248.69.1238: .
> 2429:2429(0) ack 506 win 6432 <nop,nop, sack 1 {456:506} > (DF)

Jordan
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