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Date:      Thu, 9 Aug 2001 23:05:59 -0700
From:      "Ted Mittelstaedt" <tedm@toybox.placo.com>
To:        "Nick Rogness" <nick@rogness.net>, "Eric Masson" <e-masson@kisoft-services.com>
Cc:        <freebsd-questions@FreeBSD.ORG>
Subject:   RE: DSL connectivity & ISDN backup
Message-ID:  <004701c12162$86b05820$1401a8c0@tedm.placo.com>
In-Reply-To: <Pine.BSF.4.21.0108091335110.90563-100000@cody.jharris.com>

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>-----Original Message-----
>From: owner-freebsd-questions@FreeBSD.ORG
>[mailto:owner-freebsd-questions@FreeBSD.ORG]On Behalf Of Nick Rogness

>	territory).  Like Mr. Middlestaedt mentions, paying $20-$40
>	a month for ADSL service will not be as reliable as a Leased line.
>

Unfortunately, it turns out that dial-on-demand redundancy on leased lines
isn't 100% reliable either.

Case in point - a customer of ours has a Frame Relay connection to us
using a Cisco 1604 - the frame connection comes into a WAN card in the
router, and the router is configured to bring up an ISDN call on the
ISDN port in case the Frame circuit goes offline.

The backup works perfectly if I stand next to the router and remove the
T1 Frame circuit from the DSU card.  It's also worked a few times
unattended.  (I loved the time they called complaining about slow
Internet access and our response to them was "didn't you know your T1
was down and your running on ISDN?")

But, one day the customer went offline and the ISDN circuit didn't come up.
Further investigation found that the phone company had hosed up the PVC
internally somewhere in their cloud - only problem is that at both ends
(ours and theirs) the Telco was still merrily advertising the DLCI.  Thus
the router never thought that the interface on the Frame side went down
and was stupidly sending traffic into a pipe that was going nowhere.  And
I spent at least an hour working out that particular configuration too.  Sigh.

>>
>> It would be nice to see this kind of setup handled by ppp(8) via a new
>> keyword like <backup> which parameter would be the configuration to
>> use for backup.
>>
>
>	Yes, that would be nice.
>

Ah, yes, that would indeed.  Eric - sign me up as one of your beta testers.
:-)  Only problem I can see is how does PPP know when the main circuit is back
online?  Does it keep redialing periodically or what?


Ted Mittelstaedt                                       tedm@toybox.placo.com
Author of:                           The FreeBSD Corporate Networker's Guide
Book website:                          http://www.freebsd-corp-net-guide.com





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