[nsp] Large Number of small packets --> timeout over frame relay, IGX, ATM

[Scott Weeks]

On Tue, 30 Mar 2004, Michael Axelrod wrote:

: I remember similar problems with small packets over UFM-UFM connections.
: Scott, do you recall that?

Hi Mike and Everyone,

I remember a lot of "funny" things like this on the IGX's.  It was a lot
of fun figuring it all out.  I miss the old days! :-)


: I would start with looking at the firmware versions on your UFM cards and
: trunk cards and getting that up to date.

Take Mike's advice and definitely do this!  The main thing is get someone
experienced if you're new to it and need it fixed fast.  There is a LOT to
learn and you can do damage easily.  For ATM see "ATM Theory and
Applications" by McDysan and Spohn.  I don't have a good book suggestion
for FR.  I learned it all from hands-on and cisco.com, but I don't know
if they still have the wealth of "Technology Basics" info like they used
to have.

scott


: Good luck,
: Mike Axelrod
: ----- Original Message -----
: From: "Scott Weeks" <surfer at mauigateway.com>
: To: <cisco-nsp at puck.nether.net>
: Sent: Tuesday, March 30, 2004 1:32 PM
: Subject: Re: [nsp] Large Number of small packets --> timeout over frame
: relay, IGX, ATM
:
:
: >
: >
: > Hello Everyone,
: >
: > Comments inline...
: >
: > On Tue, 30 Mar 2004, Hans-Peter Walter HAWA wrote:
: >
: > : one of our branch offices tries to connect to a self-written application
: > : in our main data center. It works, but long response times and timeouts.
: > <snip>
: > : on a Cisco 3640 in a firewall DMZ. All other applications works fine. No
: > : CPU problems, no Access-lists,  only a little bit of NAT. I had the IGX
: > ; in mind, so we changed all
: >
: > Why did you have the IGX in mind?  If it was the backbone, all apps
: > on the same PVC would show the same symptoms.
: >
: >
: > : found out, that the client only sends packets with a MTU size of 50 - 70
: > : instead of 1500.
: > :
: > : So I routed only the one application (-server) over an existing VPN
: (Cisco
: > : VPN Concentrator)  to our data center, and the connection works better,
: > : but not perfect. Response time is O.K. now, but now we have sudden
: > : connection failures  (well, it's over the Internet, I know)...
: >
: > Yes, that's why you have the connection drops, it's over the internet.
: >
: >
: > : So the only solution is to solve the frame relay, ATM, IGX or whatever
: > : problem. But I don't know where to start. I read several newsgroups,
: > : articles and googled for it, but absolutely no result. The developers
: > : can't change the MTU, so that is not an option.
: >
: > If they can't change the MTU, you're screwed.  Perhaps you could create a
: > PVC just for the app and play with it (the PVC that is... ;) until you
: > get it good enough.  However, if you're trying to do ATM w/o much
: > experience, you might do more damage than good.  Seen that happen...
: >
: > scott
: >
: >
: > _______________________________________________
: > cisco-nsp mailing list  cisco-nsp at puck.nether.net
: > https://puck.nether.net/mailman/listinfo/cisco-nsp
: > archive at http://puck.nether.net/pipermail/cisco-nsp/
:
: