Re: 2.1.111 VM and low memory machines

Chris Wedgwood (
Tue, 28 Jul 1998 18:12:04 +1200

On Mon, Jul 27, 1998 at 11:06:19PM -0700, David S. Miller wrote:

> be careful with your measurements... For example both IRIX and Digital
> Unix support it, but in the IRIX case it uses them only when clients
> make connections to _it_ advertising window scaling, timestamps, etc.
> The other way around, with IRIX, won't have window scaling or
> timestamps. This is the default configuration of IRIX and what most
> people use.
> Digital Unix, in my experience, will try to enable it not matter which
> side initiates the connection.

OK, I'll harvest a large number of host address from the sendmail and
squid logs and then write a bot to go and connect to them,
advertising wscale and use that as a metric. Virtual interfaces are
going to skew this somewhat, but there isn't much I can do about that
unless I limit myself to at one host in each /24 network or something
to minimize this effect.

> For loopback this is normal behavior, I never see this for normal
> ethernet. If you are seeing it for normal ethernet, do you happen to
> have multicasting of somesuch enabled (explicitly in ipv4 or as a side
> effect of using ipv6 at all)?

I'm seeing this for eth0, e.g. tcpdump -i eth0. I don't see it when
sniffing on the wire from another box, so I assume by loopback you
mean `same machine' and no `lo'?


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