I believe that another reason why EIGRP is so unpopular within ISP's is simply that much of its mechanistic workings are secret. With OSPF and ISIS you can read the RFC's and ISO docs to understand what is really going on, but much of the inner workings of EIGRP are kept deliberately secret by Cisco, like all the timer calculations (i.e. when to switch from multicast to unicast updates) and so forth. So when you got funny problems, your only option is to call TAC.
Cisco claims that EIGRP can scale higher than OSPF, as long as a network is designed properly. Granted, this might be just Cisco marketing talk. EIGRP definitely can't touch ISIS's scalability (but what IGP can?). ""Peter van Oene"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > Most of the largest ISP's in the world run a mix of Cisco and Juniper in > their "core". I'm not aware of any large scale SP's in North America that > run EIGRP. Further, if they are, they are likely thinking about > migrating. Running EIGRP prevents one from taking full advantage of MPLS > (TE) and also prohibits the introduction of non Cisco gear. Juniper, > Unisphere, Redback, Cosine & many others make attention worthy products for > use in these networks. Further, EIGRP simply doesn't offer the scaling > characteristics of OSPF or particularly IS-IS, nor has it been tuned for > use in ISP networks as it was primarily designed for enterprise > networks. Not to mention it has some nasty bugs, but we won't go there :) > > Pete > > > > At 07:21 AM 3/18/2002 -0500, Jeffrey Reed wrote: > >Is it a good assumption that most ISP's, big & small run Cisco routers in > >their core networks? If so, why don't they use EIGRP? I've run into so many > >Cisco routers guys in corporations who threaten holy wars when you ask them > >to move to standards-based OSPF. They claim EIGRP runs more efficiently on a > >Cisco router than OSPF... less memory, less CPU etc. If this is correct, why > >don't ISPs run that as their interior routing protocol? > > > >Jeffrey Reed > >Classic Networking, Inc. > > > >-----Original Message----- > >From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Peter > >van Oene > >Sent: Sunday, March 17, 2002 8:35 PM > >To: [EMAIL PROTECTED] > >Subject: Re: IGP's in ISP [7:38614] > > > >ISP's typically run one of IS-IS, or OSPF as their IGP's and manage only > >link and loopback address space within it. IBGP is always fully meshed, > >although most use tools like Route Reflection and Confederations to avoid > >the n*(n-1)/2 scaling issues IBGP can present. Synchronization is an > >antiquated feature that hasn't been turned on in production ISP's for > >years. Most new routing implementations do not even include the > >functionality in their BGP code. > > > >An overall design theory is to keep the IGP as small and efficient as > >possible to as to maximize convergence, and to keep everything else in BGP > >where rich tools like community based policy can be leveraged fully. > > > >pete > > > > > >At 05:52 PM 3/17/2002 -0500, Steven A. Ridder wrote: > > >Hey guys and gals, > > > > > >I have never worked in an ISP, so I have no idea how they run. I'm just > > >curious, do they run an IGP in addition to IBGP and is it fully > > >synchronized? I'm just curious to see how it's done in the real world. > > > > > >-- > > > > > >RFC 1149 Compliant. > > >Get in my head: > > >http://sar.dynu.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=38708&t=38614 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
