Re: [EXIM] Exim and ISDN (was: Exim is too fast?)

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Author: Jeff Mcadams
Date:  
To: Mark Seuffert
CC: exim-users
Subject: Re: [EXIM] Exim and ISDN (was: Exim is too fast?)
Thus spake Mark Seuffert

>I guess my last question has been stupid (?) or none of you is using an
>ISDN connection, right? I still have the problem that big mails block the
>connection for several minutes and would appreciate any experience/ideas.


>I think it should be possible to connect an small intranet via ISDN,
>actually a lot of customers do, because it's much cheaper. It's possible
>to slow down the local proxy (squid)... but what about the MTA? No other
>service makes so much traffic, that I would wish to limit the resource
>consumption. Thx a lot for help.


You probably *really* should be doing this at the router level rather
than at the application level. Depending on the routers/NAS'es that
you're using, some of them have support for this type of functionality
(traffic-shaping is what it's commonly called). I know newer versions of
Cisco's IOS has the ability to do some of this, as for other vendor
implementations...I don't know for sure.

I'm not aware of any config at the application level (exim) that can
control this well...you could probably limit it down so that only one
delivery is going to that particular host at a time, but even a single
delivery of a large file could overwhelm an ISDN line (as you're
probably aware).

If you want to do this on a larger level, where the level can support
the purchase of hardware such as these, you can look at packateer (sp?)
and xedia as both have boxes (packateer functions as a bridge, xedia can
function either as a bridge or a router) that will do traffic shaping on
a large scale and for a large number of classifications.  Xedia, I know,
can handle at least up to Fast Ethernet speeds (maybe higher?), but is
certainly not cost effective to deploy one of these boxes for a single
ISDN line!
-- 
Jeff McAdams                            Email: jeffm@???
Head Network Administrator              Voice: (502) 966-3848
IgLou Internet Services                        (800) 436-4456


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