Subject: Strange network behavior wrt tcp stream lockups
To: None <>
From: M Graff <>
List: current-users
Date: 09/09/1999 08:49:57
I am seeing some strange TCP behavior on my -current machine.

NetBSD 1.4K NetBSD 1.4K (POOFBALL.v6) #0: Wed Sep  8 23:24:56 PDT 1999 i386

If I do something over ssh, such as "cat /usr/share/misc/termcap" I
will get perhaps 10k before the session locks up.  Sometimes I get
"chunks" after a few seconds, other times I get a total lockup of that

It seems to be related to fragmentation, in that if a packet is
fragmented Bad Things happen.

My setup is a little strange:

NetBSD-current <-> router <-- gre tunnel --> home router <-> NetBSD-1.4

The NetBSD 1.4 box has problems talking to the -current machine.
However, the 1.4 box doesn't have problems talking to another 1.4
machine on the same network as the -current box.

When I turn on path MTU discovery on the -current machine, it seems to
work just fine again, since fragmentation no longer occurs.