Re: What's the best configuration for this setup?

From: Russell Street <>
Date: Sun, 24 Nov 1996 14:53:30 +1300 (NDT)

> Whoever started this thread (sorry I forgot!) claimed that a single
> (FTP?) transfer seemed to consume the entire link bandwidth.

[It wasn't me.]

I am at the end of a Frame Relay link -- 384Kb/sec CIR over a bearer
with a 512Kb/sec access rate. Our international access provider has a
T1 onto MCI.

If I hit the right site, I can get a single FTP to drive the link at
the access rate (512K). Usually it takes two FTPs to a well connected

Most of the time this does not actually happen.

Empericaly, one thing that does help in these situations is to tune
*down* the send buffers at the far end of your link. This has
mulitple good and bad effects:

- when these buffers fill up the sending site will get "source quench"
ICMP messages sent back

- the router at the far end will start dropping packets, and this
lossage will slow down the remote site as it waits for ACKs ;-)

- the round trip times on the link will go down. We did have >2000ms
RTTs but no packet loss because the packets were getting queued not

This is with cisco routers at each end of the FR link.

Fair weighted queuing and priority queueing may also help as other
people have suggested.

Received on Sat Nov 23 1996 - 17:53:48 MST

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