North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: BGP4 on a /20
Why should you concern yourself with the problems of a multi-billion dollar company like Sprint? Marcus R. Williams, Jr. [email protected] ISP Programmer / Engineer On Thu, 18 Sep 1997, Phil Howard wrote: > Date: Thu, 18 Sep 1997 18:22:19 -0500 > From: Phil Howard <[email protected]> > To: [email protected] > Subject: BGP4 on a /20 > > I'm trying to understand what all the implications of running BGP4 on > a network with a prefix longer than 19 bits. Here are some of the points > I am thinking about. > > <flameshields> > > If I go ahead and announce a /20 via two backbones, one of which is > the provider of the address space, then there will be redundant routes > for this space as the backbone provider will be announcing the /19 > (or shorter) block themselves. > > If I do this, it adds to the routing table glut, among other things. > The advantage gained is questionable. If my link to the provider that > the space comes from goes down, they are still announcing and I'll only > be able to reach where my path via the alternate provider is shorter > than the path to the down provider itself. > > OTOH > > If the provider were to be convinced to stop announcing for my /20, > then I'm going to get filtered at Sprint and AGIS and whoever else > is doing this and there won't be any /19 announcement that I can use > a default path on. > > But the real catch here is that for the provider to stop announcing > my /20 they have to split their /19 into two /20's. And if that was > really a /18 that means they will be announcing a /19 and a /20 where > before only a /18. This gets worse the larger their block was. > > Even worse than that, by doing this, they now have a /20 (the other > half of the /19 my /20 is in) with other customers who will now also > be filtered out at Sprint and AGIS and whoever else. While it can be > OK to me if I want to give up that reachability, this is also imposing > this on the other customer(s) in the other /20. So that provider is > not even likely to do that. > > So, should I add to the glut of routes or should I add to the glut of > routes? > > This needs to be simpler. > > </flameshields> > > -- > Phil Howard +-------------------------------------------------------------+ > KA9WGN | House committee changes freedom bill to privacy invasion !! | > phil at | more info: http://www.news.com/News/Item/0,4,14180,00.html | > milepost.com +-------------------------------------------------------------+ >
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