Subject: Weird TCP/IP behaviour
To: None <>
From: Paul Mather <>
List: port-alpha
Date: 11/26/2001 10:20:37
I have a DEC 3000/300 running NetBSD-current completely rebuilt
(kernel+userland) as of about a week ago.  I noticed some really weird
TCP/IP behaviour that maybe someone can shed some light upon.

For some reason, I get *terrible* speeds when FTPing *to* an AIX 4.3.3
box.  The weird thing is that I get normal speeds when FTPing *from*
that same AIX box.  Actually, it's more likely it involves FTPing *to* a
particular subnet, as the same behaviour manifests when FTPing *to* an
OpenBSD machine on the same subnet as the AIX machine (but not *from*
that machine).

I tried other machines from the DEC 3000/300.  FTP gives normal speeds
in both directions to other machines (on the same subnet).  The weird
thing is that FTPing from other machines on the same subnet as the DEC
3000/300 to that other subnet is unaffected (speeds are normal, even
from a DECstation 5000/240 running NetBSD 1.4), yet I get only about
6--10K/sec from the NetBSD DEC 3000/300.

Is there something I can disable on the DEC 3000/300 to restore normal
speeds in *both* directions?  What is causing it?

Finally, I'm running ipfilter on the DEC 3000/300, and FTP speeds seem
to max out in the low 800 KB/sec, whereas I manage the high 900 KB/sec
on the DECstation 5000/240 (and over 1 MB/sec on a DEC 3000/500S running
Digital Unix 4.0D).  Is this simply due to the overheads of ipfilter,
and, if so, is there anything I can do to improve matters?  I looked on
the NetBSD WWW site for TCP/IP tuning tips, but couldn't find anything.




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