Bug 159795

Summary:	[tcp] excessive duplicate ACKs and TCP session freezes
Product:	Base System	Reporter:	Baginski Darren <kickbsd>
Component:	kern	Assignee:	Andre Oppermann <andre>
Status:	Closed FIXED
Severity:	Affects Only Me	CC:	hiren, tasaxena
Priority:	Normal
Version:	8.2-RELEASE
Hardware:	Any
OS:	Any

Description Baginski Darren 2011-08-15 17:40:03 UTC

There is excessive duplicate ACKs and  session freezes while downloading huge files at speed over http or ftp.

tcpdump:

19:17:04.022367 IP 10.178.56.18.19930 > 10.178.132.6.80: Flags [.], ack 27950968, win 16384, options [nop,nop,TS val 977541894 ecr 783406220], length 0
19:17:04.022369 IP 10.178.56.18.19930 > 10.178.132.6.80: Flags [.], ack 27950968, win 16384, options [nop,nop,TS val 977541894 ecr 783406220], length 0
19:17:04.022553 IP 10.178.56.18.19930 > 10.178.132.6.80: Flags [.], ack 27950968, win 16384, options [nop,nop,TS val 977541894 ecr 783406220], length 0
19:17:04.022703 IP 10.178.56.18.19930 > 10.178.132.6.80: Flags [.], ack 27950968, win 16384, options [nop,nop,TS val 977541894 ecr 783406220], length 0
19:17:04.022707 IP 10.178.56.18.19930 > 10.178.132.6.80: Flags [.], ack 27950968, win 16384, options [nop,nop,TS val 977541894 ecr 783406220], length 0
19:17:04.022709 IP 10.178.56.18.19930 > 10.178.132.6.80: Flags [.], ack 27950968, win 16384, options [nop,nop,TS val 977541894 ecr 783406220], length 0
19:17:04.022856 IP 10.178.56.18.19930 > 10.178.132.6.80: Flags [.], ack 27950968, win 16384, options [nop,nop,TS val 977541894 ecr 783406220], length 0
19:17:04.023002 IP 10.178.56.18.19930 > 10.178.132.6.80: Flags [.], ack 27950968, win 16384, options [nop,nop,TS val 977541895 ecr 783406220], length 0
19:17:04.023005 IP 10.178.56.18.19930 > 10.178.132.6.80: Flags [.], ack 27950968, win 16384, options [nop,nop,TS val 977541895 ecr 783406220], length 0
19:17:04.023007 IP 10.178.56.18.19930 > 10.178.132.6.80: Flags [.], ack 27950968, win 16384, options [nop,nop,TS val 977541895 ecr 783406220], length 0
19:17:04.023151 IP 10.178.56.18.19930 > 10.178.132.6.80: Flags [.], ack 27950968, win 16384, options [nop,nop,TS val 977541895 ecr 783406220], length 0
19:17:04.023155 IP 10.178.56.18.19930 > 10.178.132.6.80: Flags [.], ack 27950968, win 16384, options [nop,nop,TS val 977541895 ecr 783406220], length 0
19:17:04.023157 IP 10.178.56.18.19930 > 10.178.132.6.80: Flags [.], ack 27950968, win 16384, options [nop,nop,TS val 977541895 ecr 783406220], length 0
19:17:04.023159 IP 10.178.56.18.19930 > 10.178.132.6.80: Flags [.], ack 27950968, win 16384, options [nop,nop,TS val 977541895 ecr 783406220], length 0
19:17:04.023200 IP 10.178.56.18.19930 > 10.178.132.6.80: Flags [.], ack 27950968, win 16384, options [nop,nop,TS val 977541895 ecr 783406220], length 0
19:17:04.023301 IP 10.178.56.18.19930 > 10.178.132.6.80: Flags [.], ack 27950968, win 16384, options [nop,nop,TS val 977541895 ecr 783406220], length 0

Fix: 

Unknown, but looks like the was similar report 

http://lists.freebsd.org/pipermail/freebsd-net/2011-February/027895.html
How-To-Repeat: Setup two boxes, connect the via 1Gbit switch and run sequential wget or fetch tests. Receiving box generates excessive ACKs and in about 40% cases tcp session freezes and then timeouts.

Comment 1 Mark Linimon freebsd_committer

2011-08-16 00:30:29 UTC

Responsible Changed
From-To: freebsd-bugs->freebsd-net

Over to maintainer(s).

Comment 2 Andre Oppermann freebsd_committer

2012-03-12 20:51:45 UTC

Responsible Changed
From-To: freebsd-net->andre

Snatch up.

Comment 3 Andre Oppermann freebsd_committer

2012-03-12 21:13:50 UTC

Darren,

could you please test these two combined patches:

http://svn.freebsd.org/changeset/base/232395
http://svn.freebsd.org/changeset/base/232396

Either this or http://svn.freebsd.org/changeset/base/220794
by jhb should fix it.

-- 
Andre

Comment 4 Hiren Panchasara freebsd_committer

2016-02-12 00:40:09 UTC

Reopen if still exists.