Date: Sun, 31 Dec 2000 13:31:47 -1000 (HST) From: Vincent Poy <vince@oahu.WURLDLINK.NET> To: Jesper Skriver <jesper@skriver.dk> Cc: Jeroen Ruigrok/Asmodai <asmodai@wxs.nl>, Christian Kratzer <ck@toplink.net>, Warren Welch <wwlists@intraceptives.com.au>, <freebsd-isp@FreeBSD.ORG> Subject: Re: Dynamic routing reference sites Message-ID: <Pine.BSF.4.31.0012311326570.2211-100000@oahu.WURLDLINK.NET> In-Reply-To: <20001231183152.A68613@skriver.dk>
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On Sun, 31 Dec 2000, Jesper Skriver wrote: > On Sat, Dec 30, 2000 at 03:52:59PM -1000, Vincent Poy wrote: > > On Sat, 30 Dec 2000, Jesper Skriver wrote: > > > A Cisco router carrying full routing today really need 256 MB of memory, > > > it can just be in 128 MB of memory, but that's VERY tight. > > > > Yeah but what I mean is that's probably with very few peers. What > > happened if you had like a lot of peers? > > -- quote -- > How Much Memory Does Each BGP Route Consume? > > Each Border Gateway Protocol (BGP) entry takes about 240 bytes of memory > in the BGP table and another 240 bytes in the IP routing table. Each BGP > path takes about 110 bytes. > > Under normal circumstances, memory utilization depends on the following > three factors: > > number of prefixes (240 bytes per prefix) > > number of routes (240 bytes per route) > > number of alternate paths (110 bytes per alternate path) > > As an example, let's say you're receiving 50,000 prefixes from four BGP > neighbors, and all of them make it into the routing table: > > BGP table: 50000 * 240 = 12,000,000 bytes > > Routing table: 50000 * 240 = 12,000,000 bytes > > Alternate paths: 50000 * 110 * 4 = 22,000,000 bytes > > In this case, you'll need approximately 46 MB of RAM, not counting the > RAM needed to support Cisco IOS Software, Interior Gateway Protocols (IGPs), > and so on. > -- unquote -- > > The above is over estimated as not all routes will have different AS > paths, the below is from a router taking 4 full views + some partial > views. > > BGP table version is 34619196, main routing table version 34619196 > 115916 network entries and 345514 paths using 23334608 bytes of memory > 75815 BGP path attribute entries using 3639120 bytes of memory > 471 BGP rrinfo entries using 11304 bytes of memory > 60418 BGP AS-PATH entries using 1502272 bytes of memory > 379 BGP community entries using 10516 bytes of memory > 98416 BGP route-map cache entries using 1574656 bytes of memory > Dampening enabled. 290 history paths, 72 dampened paths > BGP activity 794102/678186 prefixes, 23640513/23294999 paths This is pretty interesting since I know it seems like everyone seems to show a different amount of routes depending upon which Cisco router is looked upon. > > And a question, on a Cisco > > router, does the following basically do the route announcements? > > > > router bgp <your ASN> > > bgp dampening > > BGP dampning has nothing to do with announcing routes, go read the > documentation, it's public available. I know what it does, it has something to do so the router doesn't flap according to what Avi Freedman wrote but it seems like there is no way to do this statement in zebra. > > network x.x.x.x > > > > So basically it will announce the network x.x.x.x to the upstream > > provider with my ASN on it and then the upstream will automatically add > > their AS to it when it announces up another level? > > Yes, this is how BGP works. Thanks, after reading all the docs, I was a bit lost in how to do the announcement of routes since I know how to take the routes from the peers. Cheers, Vince - vince@WURLDLINK.NET - Vice President ________ __ ____ Unix Networking Operations - FreeBSD-Real Unix for Free / / / / | / |[__ ] WurldLink Corporation / / / / | / | __] ] San Francisco - Honolulu - Hong Kong / / / / / |/ / | __] ] HongKong Stars/Gravis UltraSound Mailing Lists Admin /_/_/_/_/|___/|_|[____] Almighty1@IRC - oahu.DAL.NET Hawaii's DALnet IRC Network Server Admin To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-isp" in the body of the message
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