From: Pierre-Alex Guanel (pierreg@planetkc.com)
Date: Thu Jul 08 2004 - 17:48:35 GMT-3
Hi Howard,
This is the basic idea I had in mind.
It looks like if I wanted to know the details I would need to spend the time
reading the RFC
and doing it step by step. Could be of good use for academics but for the
lab, I am not quite sure.
Thanks for your input.
Pierre
----- Original Message -----
From: "Howard C. Berkowitz" <hcb@gettcomm.com>
To: "Ccielab@Groupstudy.Com" <ccielab@groupstudy.com>
Sent: Wednesday, July 07, 2004 7:38 PM
Subject: Re: Advanced: OSPF Algorithm
> At 7:23 PM +0100 7/7/04, Pierre-Alex Guanel wrote:
> >How does OSPF add the cost of the links?
> >
> >>From what I have seen, it does not seem like the cost in the packet gets
> >updated from hop to hope.
> >
> >The process of flooding just passes the original lsa along, unaltered.
> >
> >>From what I read, the OSPF algorithm knows how to find all the costs
and add
> >them up from the LSA using the Djakstra algorithm.
> >
> >Yes I know its all explained in RFC 2178 ...section 16, but I am
looking at
> >a simple explaination.
> >
> >thanks,
> >
> >Pierre
>
> Let's keep this at the intra-area case at the moment, which is all
> the Dijkstra algorithm cares about. Link state protocols do not
> transmit routes, but router links (and a list of subnets connected to
> them) and network/subnet links (with a list of router interfaces
> connected to them).
>
> The Dijkstra algorithm builds a tree, matching up the
> networks-with-routers and the routers-with-networks. Each time it
> steps closer to a destination, it picks the lowest interface cost at
> that hop. When the final best paths are selected, OSPF adds up the
> costs along the path, and then sends the route to the routing table
> installation process. The intra-area routes are never passed to other
> routers during flooding. Route metrics are computed independently by
> each router, from its own position in the topology.
>
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