[1211] in linux-net channel archive
IP forwarding kills TCP with moderate loads
daemon@ATHENA.MIT.EDU (Joshua M. Thompson)
Fri Oct 13 06:32:23 1995
Date: Thu, 12 Oct 1995 22:31:46 -0500
To: linux-net@vger.rutgers.edu
From: invid@optera.com (Joshua M. Thompson)
I just upgraded to an ISDN link (64k for now, 128k once I upgarde my 3Com
Impact firmware) and I'm having a major problem with IP forwarding.
My setup is this: at work there is a 3Com Impact hooked up to a Livingston
Portmaster at 115.2k bps and set as a hardwired PPP link. At my end I have
the same 3Com unit on a 16550A serial port at 115.2k, using PPP 2.2 and
Linux 1.3.29. IP forwarding is on and I am routing an entire Class C from
work into the Ethernet in my house. The machine is a 486DX/2 66 with 12
Megs of RAM, and very little load (it mostly does mail serving and
routing).
The problem is this: under any moderate load over the ISDN link, the entire
TCP system would simply FREEZE! And it's not just the ISDN link that's
affected; even Ethernet connections freeze and eventually time out.
Shutting down the ISDN link to hault the packet flow is the only solution
to unfreeze the network.
For the moment I have lowered the port speed to 57.6k and this seems to be
working for now. But I paid extra money to buy 128k-capable TAs and I want
to use all my bandwidth. Even now I am wasting bandwidth running at only
57.6k bps. I suppose in a week or so I could spring for a small
router...Compatible Systems makes the MicroRouter 900i (one Ethernet, one
async serial 115.2k serial port) for around $735. But I'd rather not put
that much more money into this just yet.
Any ideas? Would a newer kernel help me? I've stuck with 1.3.29 since it's
been stable for me but if this is a known bug I'll happily upgrade my
kernel.
--
invid@optera.com "This is God, concluding my broadcast day..."
http://www.optera.com/~invid - MST3K, "The Magic Voyage of Sinbad"
PGP fingerprint: 90 05 50 DA 0E 18 CD 47 C5 25 83 1F A5 41 17 73
