[nsp] Is default failover in dual-homed DSL possible?

[Josh Duffek]

talk to your sales guys about feature bug CSCds88143.
joshd.

----- Original Message -----
From: "Mark Boolootian" <booloo@ucsc.edu>
To: <cisco-nsp@puck.nether.net>
Sent: Monday, December 16, 2002 6:23 PM
Subject: [nsp] Is default failover in dual-homed DSL possible?


>
> Folks,
>
> I'm looking for a solution for home/business DSL users who want dual-homed
> DSL connections to protect against outages.  The basic picture looks like
> this:
>
>
>        ----------         -----------
>        |  ISP 1 |         |  ISP 2  |
>        ----------         -----------
>            |                    |
>            |                    |
>            |                    |
>           -----               -----
>           |   |               |   |  <- DSL modems
>           -----               -----
>              \               /
>              ----------------
>              |   router     |
>              ----------------
>                     |
>                     |
>             --------------------
>
> The router is doing NAT, and there is no dynamic routing protocol running
> between the router and the ISPs (i.e. typical home DSL setup).  The
question
> is, are there any products/mechanisms for allowing a static default
pointing
> at one ISP to failover to the other ISP in the event of a network outage
> at the first ISP?
>
> In the above diagram, a failure with DSL would take down the PPP
connection,
> so presumably if the DSL modem were built-in to the router, the router
would
> notice that the PPP connection was down, and perhaps the right thing could
be
> made to happen.  Unfortunately, I don't know of a small router that would
> accommodate this solution.  I suppose if one were to terminate each DSL
> connection in an individual router, and then feed both those connections
into
> a third router, one might be able to manufacture something that would
work,
> but I don't think I'd want to put that on my resume (much less mention it
on
> this list).
>
> In order to accomodate failures beyond a dead DSL link, I've got a rather
> messy idea in my head of a box sitting on the LAN pinging nameservers in
each
> of the ISP's networks, and making routing changes on the router
accordingly.
>
> Has anyone on this list set up anything to deal with such a situation?
>
> Thanks very much,
> mb
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