Configuring multi-home failover

Mike Stubbers mikest at
Fri Jan 18 20:51:14 UTC 2002

> -----Original Message-----
> Stephane Bortzmeyer
> To: Mike Stubbers
> On Friday 18 January 2002, at 11 h 46,
> "Mike Stubbers" <mikest at> wrote:
> > I am wanting to configure a secondary ISP to be used as fail
> over only for our primary.
> Most people who have two links use them also for load-sharing. A
> link to an ISP is expensive enough so you don't want to keep it unused
> in case".  Is it because the second ISP charges a lot according to the
> volume actually transfered?

Given our rural location, the high cost is in the circuit not the service.
We have contracted with a local ISP to utilize their bandwidth, but they do
not have continued capacity to support load balancing effectively.  When our
primary fails we understand our secondary will become saturated as well
upstream.  Not a pretty solution, but affordable for the moment.  So yes, we
need to use this as backup only.  The pricing model has this built in.
We'll pay very little to have the reserve in place, but face penalties when

> >  At this point both ISP's come into the same 7500 router.  So much for
the redundancy.

Agreed, see affordable note above.  Historically most of our outages have
come from a local farmer during spring work, or a redneck with a shotgun.  I
can repurpose equipment as needed in an emergency.

> > have an established BGP session with our primary provider.
> Do you have a private AS number or already a public one?

We have a public AS in place already.

> > Can those of you doing this already tell me the optimum way to
> > set this up?  Is this best done on my end or by having my secondary
discover our
> > disappearance and begin announcing?
> I would say that it is better done on your end because it will
> allow you to change your policy (see above my remarks). Also, it
> is "the normal way" of operation for BGP.

Thanks for your input.

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