Date: Tue, 1 Oct 2002 00:15:59 -0400 From: "Troy Settle" <troy@psknet.com> To: <freebsd-isp@FreeBSD.ORG> Subject: RE: Multihoming alternatives Message-ID: <001601c26901$404df5d0$2615c518@psknet.com> In-Reply-To: <5425A7F4-D4C4-11D6-A6AC-000A27D85A7E@mac.com>
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> -----Original Message----- > From: owner-freebsd-isp@FreeBSD.ORG > [mailto:owner-freebsd-isp@FreeBSD.ORG] On Behalf Of Chuck Swiger > Sent: Monday, September 30, 2002 6:31 PM > To: freebsd-isp@FreeBSD.ORG > Subject: Re: Multihoming alternatives > > On Monday, September 30, 2002, at 06:08 PM, Ralph Forsythe wrote: > > On Mon, 30 Sep 2002, Chuck Swiger wrote: > >> [ ... ] > >> Yes, although a /24 isn't guaranteed to be globally routable. > > > > Yes, quite the opposite, it's all but guaranteed to NOT be globally > > routable. AFAIK there is a big push for route > consolidation, and many > > larger route points will not even pass a route entry for > something that > > small. > > Right-- most ISPs don't host routes smaller than a /20, > simply because the > amount of memory required to hold even that subset of network > routes is > around 128 MB. Actually, you can fit 3 full route tables (~112k routes each) into 128MB, I've done it. No guarantees on router performance though. Currently, I'm taking 3 views on a 7206 w/512mb. For 2 full views, I'd probably recommend a minimum of 192mb. > > On the other hand, as an end-user organization, you only need > to worry > about prefered routes via one link or the other for networks > which (a) you > care about, and (b) see a significant difference in > reachability via one > provider versus the other. So the OP could get away with using Cisco > 1xxx-grade routers with only 32 MB on his side. Right. In this scenerio, you could actually get away without taking /any/ routes from your upstream providers. Just use 2 default routes for your outbound traffic and BGP to announce your own space, which takes care of your inbound traffic. You could do this on even an old 2501. As for a /24 not being routable, I agree that it can cause problems, but in 5 years of doing it, I've not run into any yet. I have 4 /24 and 2 /23 networks assigned to me by Sprint. I announce these to all 3 of my providers (Sprint, AT&T, and UUNut). I've yet to receive a complaint of an unreachable network due to some under-funded idiot having filters on announcements smaller than a /20. I assume the reason for that, is becaue said idiot had at least enough sense to leave default route entries in place. This is a moot point anyways, as I'll bet you couldn't name me one person who will guarantee any network of any size to be globally routable, as there is no single entity that controls routing policies on all 25k+ autonomous systems on the 'net. -- Troy Settle Pulaski Networks 540.994.4254 - 866.477.5638 http://www.psknet.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-isp" in the body of the message
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