Re: Fix for SLOW PPP Bug

Nick Holloway (Nick.Holloway@alfie.demon.co.uk)
11 Apr 1996 08:23:07 +0100

Jason Eggleston <jegglest@scf.usc.edu> writes:
> I tried Linus' suggestion, and it had no effect (that I could perceive).
> Solaris hosts are still slow. I should now be subscribed to this list,
> if anyone wants more data from me.

I think Solaris is just very bad at dealing with large RTTs such as you
get over a 14.4k PPP link. It doesn't wait long enough for the ACK,
and resends the packet. This affects more than just Linux.

The machine I pull news from is a Solaris machine, and I see that
problem there. This has actually been improved by reducing my MRU to 576
(I was playing with 1500 since Linux has MTU discovery).

Demon have improved it by the following settings for the Solaris box:

tcp_rexmit_interval_initial 1000 (1 second)
tcp_rexmit_interval_min 600 (.6 seconds)
tcp_rexmit_interval_max 60000 (default)
ip_path_mtu_discovery 0 (off)

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