Solution that Worked, Re: (PM) Excessive Renegotations w/ v.90?

Greg Hughes (greg@cyberport.com)
Wed, 6 May 1998 20:02:14 -0600

When connecting V.90 with my USR modem, I found that I was seeing
performance fluxuations in a big and bad way. The connection would often
hang, and ARQ actions were WAY up. I disabled v.42bis (&K0) and forced
hardware flow conteol on and software flow control off (&F1). This is on a
Unix box that I use as a small LAN router at home. Oncer I made these two
changes:

1. Ping times to the terminal server improved drastically
2. Renegotiations decreased dramatically
3. ARQ problesm nearly disappeared
4. Throughput increased on compressed file downloads

I am now seeing downloads in the range of 5.35 Kbps on a fully-compressed
zip file, where throughput prior to the change was erratic and well below
4.8 Kbps.

At any rate, it worked on my end!

Greg Hughes

-----Original Message-----
From: John W Baxter <jwblist@olympus.net>
To: James Laszko <james@tfbnet.com>; portmaster-users@livingston.com
<portmaster-users@livingston.com>
Date: Sunday, May 03, 1998 10:46 PM
Subject: Re: (PM) Excessive Renegotations w/ v.90?

>At 15:05 -0700 5/3/98, James Laszko wrote:
>>I've got one of our techs who's got a v.90 USR Sportster at home that is
>>experiencing an unusually high number of renegotiations whenever he dials
>>in. When he first connects, he'll connect at about 48000. After
>>transfering 100K or so, he'll renegotate (Amber shows his TR speed 50666)
>>and then drops down to the low 30K's, and transfer 10-20K more, and then
>>renegotiate again (50666 again) and drop to anywhere from 30-48K. This
>>continues about 20 or so times (at this point he's normally got about
>>500-600K transferred) and it stabalizes at 48000 and chugs along. Anyone
>>else seeing this?
>
>I am seeing similar renegotiations on the test USR X2/V90 modem I bought
>recently. They are particularly evident when I call from home (where I use
>modems, and from which I work). "Home" is in the 360-437 exchange, which
>is a "Flex-free zone", although V.90 does limp along (with the
>renegotiations).
>
>In about 5 cases, the renegotiations were particularly frequent (most
>packets seemed to trigger them), and those connections eventually dropped
>(the renegotiation count was in the low three figures). Removing other
>load from the phone line seems to have helped.
>
>Here's the connection I'm using at the moment (it began at 48000, and went
>to 44000 before I could check it in the PortMaster):
>
>show m0
> Card Type: Lucent Chipset
> State: ACTIVE
> Active Port: S3
> Transmit Rate: 44000
> Receive Rate: 21600
> Connection Type: LAPM/V42BIS
> Chars Sent: 100966564
> Chars Received: 13096051
> Retrains: 0
> Renegotiations: 18
>
> --John
>
>
>--
>John Baxter jwblist@olympus.net Port Ludlow, WA, USA
>Give a man a fish and you feed him for a day. Teach him to fish,
>and you get rid of him for the weekend.
>-
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