RE: BGP Default Route

["Martin, Christian" <cmartin () gnilink net>]

> On Sat, Sep 14, 2002 at 02:18:15PM -0400, Lupi, Guy wrote:
>
> > I was wondering how people tend to generate default routes to
> > customers running bgp.
>
> Short answer: don't
>
> Longer answer: To solve the exact problems you mention below,
> only advertise a aggregate block of your own to this customer,
> say x.x.0.0/16, then the customer will configure his device
> something like
>
> ip route 0.0.0.0 0.0.0.0 x.x.0.0
>
> or
>
> set routing-options static route 0.0.0.0/0 next-hop x.x.0.0 resolve
>
> This will ensure that if the border router get's isolated, it will no
> longer advertise x.x.0.0/16 to the customer, and the customer 
> router can
> choose a backup path.

What if the aggregate is local to the border router?  If you want to avoid
this problem, you will have to use a route that originates from somewhere
away from the border.  This is more work than is necessary, IMO.  If your
border router is isolated, you have a design problem or a failure state that
is just as likely to occur(if not moreso) than the border router failing.

What I will say is that a "full-table" peer should not get a default route
at all.  Of course, this isn't very enforcable.  In any case, providing a
default is not something I would say shouldn't be done, IMHO.

Thanks,
chris


> /Jesper
>
> -- 
> Jesper Skriver, jesper(at)skriver(dot)dk  -  CCIE #5456
> Senior network engineer @ AS3292, TDC Tele Danmark
>
> One Unix to rule them all, One Resolver to find them,
> One IP to bring them all and in the zone to bind them.