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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: Confussion over multi-homing
Of course, peering agreements may speak to route filtering at that particular interface, but can't assure global routability. For all intents and purposes, /24s are globally routable, but their are several meaningful exceptions - Verio and legacy class B space come to mind. Daniel Golding Director of R&D "I'm not evil. I'm just drawn that way" NetRail, Inc. 1-888-NetRail On Thu, 14 Sep 2000, Brantley Jones wrote: > > At 01:23 PM 9/14/2000 -0500, you wrote: > > >Wouldn't one of the ISPs have to advertise a longer prefix? I would think > >that the address space would come from only one of the providers, in which > >case the other provider would have to advertise this space on top of its own > >/20. It is irrelevant whether the two ISPs advertise one another, the > >longer prefix would be the first choice for the backbone traffic. If the > >longer prefix route goes down, traffic would still go to the /20 the other > >provider is advertising. > >The ISP who is advertising the route on top of its own /20 can't aggregate > >said route as it only can route to that portion of the address space defined > >in the longer prefix. > > > >Geoff Zinderdine > > The problem is GETTING a /20 from anybody. We recently tried and could > only get a /23 (being a small start-up). BUT, that /23 is (apparently) > globally routable because of peering agreements with L3 and UUNET. Our /23 > prefix has yet to be filtered by anybody. > > Brantley > >
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