Re: Network Performance?

[Tim Sailer]

On Mon, Jan 08, 2001 at 09:26:23PM +1100, Andrew Morton wrote:
> Tim Sailer wrote:
> > 
> > On Sat, Jan 06, 2001 at 10:11:40PM +1100, Andrew Morton wrote:
> > > this issue was discussed on the netdev mailing list a few weeks
> > > back.
> > >
> > > It's very unfortunate that the web archives of netdev
> > > stopped working several months ago and there now appears
> > > to be no web archive of [e-mail].
> > >
> > > Go to http://oss.sgi.com/projects/netdev/archive/ and
> > > pull down the November and December archives.
> > >
> > > The subject was "linux to solaris tcp issues on WAN".
> > >
> > > The conclusion was "The problem is also fixed with
> > > 2.4.0-test12pre3". Dunno about kernel 2.2 though.
> > 
> > Well, on Friday, we pulled down the 'official' 2.4.0, and had the
> > same experience... nothing better. Should I get the -test12-pre3 kernel
> > and try that one specifically?
> 
> I doubt if that would help.
> 
> I claim no expertise in this area, but perhaps we can
> get some protocol gurus interested.
> 
> To recap:
> 
> You're sending and receiving FTP/TCP/IP4 to Solaris and AIX hosts

Yup

> You have a 1000kbyte window size

Yup

> You have an 80 megabit/sec pipe.

Actually, 100 to the router, and then the WAN connection to the remote
system is OC-3

> You're getting 1.8 megabits/sec.

Yup

> What is the round-trip time on the WAN?
> 
> Packet loss?

101 packets transmitted, 101 packets received, 0% packet loss
round-trip min/avg/max = 109.6/110.3/112.2 ms

> Does the problem occur in both directions?

Good question. I'll find out.

> Are you _sure_ the window size is being set correctly? How
> is it being set?

I'm fairly sure. We echo the value to the file. catting it back
shows the correct value. If we go lower than default, it slows
down even more.

> Are you able to generate TCP dumps when the problem is happening?

We can, if it will help.

Tim

-- 
Tim Sailer <[e-mail]> Cyber Security Operations
Brookhaven National Laboratory  [phone]