[tahoe-dev] how to see performance numbers (Re: linuxpal updated)

Nathan Eisenberg nathan at atlasnetworks.us
Fri Mar 25 21:45:34 UTC 2011

> This sounds more plausible.. we've historically had problems with silently-
> disconnected TCP sessions (either caused by NAT table entries being
> dropped or laptops being closed). There are tahoe.cfg options to turn on
> keepalives ([node]timeout.keepalive and .disconnect), but the default
> tahoe.cfg leaves them blank, which tells the underlying foolscap Tub to use
> its own defaults, which are keepalive=4*60 and disconnect=None. This
> means every four minutes it will send a keepalive if nothing else has been
> sent in the previous four minutes (so worst-case is one message every 8
> minutes), and it will never drop the connection just because of a timeout.
> See ticket #521 for a discussion about choosing timeout values.. maybe your
> firewall is silently dropping the outbound connections in like 5 minutes of
> inactivity.

FWIW, the most aggressive state tables I've encountered 'in the field' have lifespans of ~120 seconds.  I'm sure some devices are worse, but 90 seconds seems to be a safe keepalive threshold for another application that NAT likes to muck up - VOIP.  8 minutes, though, is probably long enough that many firewalls will drop the state.

Hrm... what if tahoe automatically established IPSEC tunnels instead of plain jane TCP connections?  ;)


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