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SubjectRe: Skyhigh retransmit times. Yearold problem still in 2.3.26
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Date
steveu@infowebtelecom.com (Steve Underwood) writes:

> Andi Kleen wrote:
>
> > christoph@lameter.com (Christoph Lameter) writes:
> >
> > > I have been bitching about this for years ....
> > >
> > > This is for a ssh connection via a ricochet:
> > >
> > > netstat -ton
> > >
> > > tcp 0 0 127.0.0.1:1026 127.0.0.1:1027 ESTABLISHED off (0.00/0/0)
> > > tcp 0 0 204.179.131.123:1745 207.33.153.134:6667 ESTABLISHED on2 (7106.08/0/0)
> > > tcp 0 0 204.179.131.123:1023 207.33.153.134:22 ESTABLISHED on2 (6455.34/0/0)
> > >
> > > If there would at least be a command to reset those times to make the
> > > connection usable again.... This way I have to establish a new connection
> > > to the same host to do something usable.
> >
> > Once you get through again TCP will reset the timeouts itself as it
> > receives new ACKs.
>
> Whilst this is true, I think many people would describe a protocol that allows 2 hour retransmits
> as broken. Were its designers looking for reasonable results on links between the Earth and Mars?

It was designed to tolerate longer down times of paths without too much
impact. If down connections would lead to short retransmit tries it could
bog down immediate links.


>
> This is quite a pain with TCP across unreliable media (e.g. the Internet). A broken path gets
> fixed after some significant downtime, but established connections take an age to pick up again.
> There has be a Better Way.

KA9Q has a "kick" command for TCP connections for this purpose. It wouldn't
be very hard to implement it in Linux.

-Andi

--
This is like TV. I don't like TV.

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