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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: IGPs in use
[email protected] (Howard C. Berkowitz) writes: > When I gave my OSPF tutorial at NANOG in June, I stressed OSPF shouldn't be > thought of purely as a 2-level hierarchy with a routing domain consisting > of an area 0 and a set of nonzero areas. Some of the OSPF scaling > problems I see, and these are probably equally likely in IS-IS, come from > people trying to put everything into a single OSPF routing domain. Aside > from performance issues, this can become a network administration nightmare. > > Splitting the interior network into several IGP routing domains, and > linking these with a backbone-of-backbones, helps both performance and > administration. The backbone group doesn't need to be concerned with LAN > installations in a POP or customer site. Depending on the particular > network, you might link IGP routing domains with: > > -- static routes > -- iBGP, putting all IGPs in a single AS > -- iBGP and eBGP in a confederation > -- Hybrid layer 2/3 techniques, such as linking IGP-routed domains > to internal layer 2 "superhubs" > > How much IGP support you need will depend on your network. A large > enterprise, or a provider of both connectivity and content, will probably > need more IGP stuff than a pure connectivity provider. Howard, Yes, those sound like a list of administrative nightmares. ;-) Wouldn't it be much easier to make use of a three or four level hierarchical IGP? Tony
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