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

[Scott Weeks]

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