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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: BGP Default Route
On Sun, Sep 15, 2002 at 07:32:23PM -0400, Martin, Christian wrote: > > 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. Yes, I guess that is the most normal senario, the aggregate routes are sourced at a set of routers at different pop's, but not all border routers. > 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. That is no argument, there is a probability that a border router get's isolated, and the above solution will handle that problem too, how likely or unlikely that failure might be, which highly depends on the design. > What I will say is that a "full-table" peer should not get a default > route at all. Agree > Of course, this isn't very enforcable. In any case, providing a > default is not something I would say shouldn't be done, IMHO. /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.
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