>Hey all, > > I've been reading into BSCN here lately with Cisco press >books. In the book >there is a fairly detailed discussion of OSPF. I'm not in the least opposed >to learning it. One thing I would like to understand is why an organization >would use it. Is this used in ISP's? What are the advantages of it over say, >EIGRP? I always see it compared to RIPv1 but I find it silly for advanced >routing protocols to be compared with ripV1. I'll preface my remarks with the observation that all three advanced IGPs: OSPF, EIGRP, and ISIS, all work well. ISIS is more a niche protocol for ISPs. There are pros and cons for each one. OSPF and ISIS require structured network topology from the very beginning, while EIGRP is much more tolerant -- up to a point. For me, the definitive comment came over a few beers shared with a distinguished Cisco engineer. He observed, "to build a really big network, you absolutely have to have clue." He burped loudly, and then went on. "EIGRP has the advantage of letting you stay clueless for longer." The biggest argument against EIGRP is that it is Cisco proprietary. Being proprietary has implications beyond the multivendor question. Because some of the EIGRP mechanisms have not been published by Cisco, there isn't the external knowledge base about EIGRP that there is about OSPF and ISIS. Protocol and network architects have a very deep understanding how OSPF and ISIS will behave and what their strengths and weaknesses are, but no one who hasn't been a Cisco employee can have the same sort of insight. For similar topologies, EIGRP generally needs less processing than OSPF. On the other hand, with ever-faster processors, this may not be a significant constraint. In a fair test, with equivalent timers set to equivalent values, both converge very fast, and convergence time should not be an issue with any protocol (assuming reasonable network topology). EIGRP may be able to find an alternate path faster when that path goes through a neighbor, but OSPF is faster if the alternate path might be several hops away. If you run Appletalk or IPX routing, there is a definite advantage to using EIGRP. EIGRP also can bring incremental updating to a Netware 3.x environment that can't be upgraded. A few things to consider. > > >Please forgive me if this is shortsighted of me. > >Thanks in advance, >Dave > >_________________________________ >FAQ, list archives, and subscription info: >http://www.groupstudy.com/list/cisco.html >Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] _________________________________ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
