TCP Reassembly Issues

Raul raul at turing.b2n.org
Fri Nov 25 08:51:29 UTC 2011


El 24/11/2011 23:06, Stefan Bethke escribió:

[....]
 > I regularly copy large files off my Tivo trans-atlantic (125ms RTT),
 > and TCP connections currently stall after about 500 megs, never
 > recovering.  I suspect this is connected, as it started immediately
 > after upgrading the machine to 9-stable.

I've not seen not recovering nor completely stalled (mpd tcpmssfix 
related?).

What I see is a normal start, normal bandwidth increase, peak 
performance using all available bandwidth and after that bandwidth drops 
to a 'unreasonable' level and stay there most of time during transfer.

Numbers always depend on too much factors, but to illustrate how 
dramatic it is:

[....]
%ping -c100 XX.au
PING XX.au (136.186.XX.XX): 56 data bytes
...
100 packets transmitted, 100 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 352.036/354.258/374.731/3.593 ms
[....]

downloading by ftp an iso image from that host (wget), transfer peaks at 
about 1.4MBytes/sec before falling up to 2,9?KBytes/sec where most 
transfer happens.

Please note, this numbers come from a pppoe link (DSL) established by 
mpd55 with *'tcpmsswilink'*:

[....]
%cat /usr/local/etc/mpd5/mpd.conf | grep fix
         set iface enable tcpmssfix
[....]

I hope that shed some light.

Regards,
Raúl.


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