Talk:Open Shortest Path First
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The remark concerning Type 5 advertisements and Stub Areas is in fact correct. Type 5 carries AS-external routing information, and a Stub Area only has one connection towards the backbone, thereby eliminating the need for a detailled routing information. Stub Areas are usually only fed a default route and maybe the AS-internal routes (Type 1-4), but they don't need to know about the AS-external routes. Sigkill 02:06, 1 July 2006 (UTC)
"Intra-area routing goes via the backbone"
Is this really correct? It would seem more logical if inter-area routing was done via the backbone. --K. Sperling 10:33, July 20, 2005 (UTC)
- True, and is corrected meanwhile. Sigkill 02:06, 1 July 2006 (UTC)
"In contrast to RIP or BGP, OSPF does not use TCP or UDP but uses IP directly, using IP protocol 89."
This sounds incorrect Routers are layer 3 devices so how can they use Transport Layer, Layer 4, services?
- While some routing protocols use L4 transports (such as tcp/179 for BGP or udp/520 for RIP), others bring their own L4 protocol (such as (E)IGRP with L4-protcol number 88 or OSPF with L4-protocol number 89). You should distinguish between the actual routing task running on Layer 3, and the inter-router communication, which uses higher-level protocols. Sigkill 02:06, 1 July 2006 (UTC)
Could a list of entry level Products which support OSPF be added, so others can learn by 'doing'?
- Added meanwhile. Sigkill 02:06, 1 July 2006 (UTC)
[edit] A good introduction article
I think this guy has done a good job on introducing the topic. Its a little Cisco oriented, but unlike the corporate literature, his writting style is human, or what Art Kleiner call "native" in his book The Age of Heretics.
One thing that I found confusing though, what is the explicit message behind this paragraph? Does he imply that OSPF can not scale? I am betting its communication problem as the guy seems to know his stuff really well
"The U.S. Post Office is putting in 38,000 Cisco routers. Note that if we use our rules of thumb, 38,000 divided by 100 routers says we'd need 380 areas. Alternatives include multiple OSPF AS's, and other protocols (like EIGRP). I'd very definitely want healthy route summarization in such a network. Note that since OSPF only allows us to summarize at ABR's, we can only have one level of summarization. With 38,000 routers, we might well want to summarize at the regional, state, and portion of state levels. That can't be done with pure OSPF." [1]
