In an environment that large with no clearly defined area 0, would not IS-IS also be a viable choice from a technological standpoint? I understand that not as many people are familiar with it but it seems like it might be a good fit there.
It seems like the argument is always EIGRP vs OSPF, but I think people really should consider IS-IS in the mix if it fits. What are your thoughts? John >>> "W. Alan Robertson" 12/13/01 12:14:40 PM >>> One reason that you may prefer EIGRP over OSPF would be in a particluarly "meshy" environment. In an OSPF network, inter-area traffic must pass through area zero (commonly called the core). Traffic between Areas 1 and 2 must be sent through Area 0, even if Areas 1 and 2 have a direct connection. This is the default behavior, which can be addressed in a number of ways (virtual links, extending area 0, etc), but you'd hardly want to start off having to resort to this kind of trickery. EIGRP, on the other hand, would handle this configuration out of the box, and you would get desirable traffic flows without having to do anything fancy. 1 year ago, I was deploying a network for a large federal institution that had 3 Main locations, and over 2000 satellite locations that were triple homed to each... The main locations had dozens of routers, and each router hundreds of connections (Frame-relay circuits, with a lot of DLCIs per circuit). There was no good location to define as Area 0, as an equal amount of traffic would be going to each of the 3 main locations. OSPF, as much as I like it, is not well suited to an environment like this. EIGRP, with a good addressing plan, and good summarization, handles it like a champ, and will continue to scale even if they add another 2000 sites. Summarize everything you can, everywhere that you can, and keep that in mind while figuring out your addressing. The biggest mistake that people make when deploying, or living with, and OSPF network, is that they tend to get sloppy with Area 0. If your topology doesn't allow for a clearly defined core, then you probably shouldn't try to force it... OSPF will make you pay later, and dearly. Look at your topology, and the flow of traffic that you anticipate... >From what you have described below, you seem to have a topolgy that would probably work well with OSPF. It sounds like you will have a Core location, and that you anticipate any Remote-site to Remote-site traffic to come through the core anyway. OSPF will probably work out well for you, but don't feel like you have to switch to it. An elegantly designed network, with good addressing and summarization is impressive regardless of routing protocol. Don't let it become a Holy War... Protocol selection should be dictated by topology, design goals, and supporability (Does your networking Team have sufficient experience with OSPF? They already know, or are at least familiar with EIGRP); don't let it become about religion. ;) Alan~ ----- Original Message ----- From: "Mears, Rob" To: Sent: Thursday, December 13, 2001 12:40 PM Subject: RE: OSPF or EIGRP [7:28966] > Hi All, > > To your question; we are, as all should be, a pure IP and Cisco shop (:. > As to why we originally went Eigrp, who knows it was before my time but I > would guess Cisco had some influence on it, but now we are growing and plan, > no not plan but have bought the routers\switches for 400 locations and will > be deploying @ the beginning of the year. > > I know EIGRP will scale well and will handle our growth for the time being. > As my research points, we will be good with EIGRP for a long time and the > differences I found between the two are really nominal. But since the > network we are rolling out is in parallel to the present, we do not have to > worry about the migration part, so we have the opportunity to do it right > and impress people long after I am gone. > > So correct me where I am wrong and please show me the light OSPF or EIGRP. > > > Thanks > Rob > > -----Original Message----- > From: Gregg Malcolm [mailto:[EMAIL PROTECTED]] > Sent: Wednesday, December 12, 2001 3:40 PM > To: [EMAIL PROTECTED] > Subject: Re: OSPF or EIGRP [7:28966] > > Rob, > > Few questions. What routed protocols you plan to run? Just IP or > IP/IPX/AT,etc.? Any other vendor equipment other than cisco? Firewalls > running OSPF for failover? Why did you initially choose EIGRP? Does the > network design lend itself well to a backbone area? Redundant links > (including DDR) ? > > I think if you can answer some of these questions, it will help the group > give you a better response. > > Gregg > > > ""Mears, Rob"" wrote in message > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > Hi all, > > > > We are in the middle of building out a new ATM network for the Core and on > > the outside we are going to be running about 80 3640 or 2600. We are in a > > big debate about the routing protocol, we are currently EIGRP. > > > > I have collected lots of info off Cisco's Web site about the two but > wanted > > to hear it from the Engineers in the trenches. > > What's your take on it? If it were you what would you run (EIGRP, OSPF) > and > > why? > > > > > > > > Thanks > > Rob [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=29132&t=28966 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
