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Re: EIGRPs DV characteristics [7:80025] posted 12/02/2003
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"Chuck Whose Road is Ever Shorte wrote:
> actually EIGRP does use hop count,

Yes, but only for faster loop-detection.

> but it doesn't show up in the tables anywhere.

show ip eigrp topo  

> Max hop count can be changed using some command or other.

metric maximum-hops

> EIGRP routers outside of the diameter will be unable to
> send or receive routes to the other side of the diameter.

Only because routes longer than the max_hopcount are part of a loop by
definition.

To address the original question, I was surprised when I learnt that
distance vector protocols are defined based on an algorithm like
Bellman-Ford (which is a very generic graph algorithm). To me, this is what
really differentiates distance vector protocols from link state protocols:

> > When a router running EIGRP receives a distance vector from a
> > neighbor, it
> > determines whether its cost of reaching any destination would
> > decrease if
> > packets to that destination were to be sent through that
> > neighbor. If so,
> > that router updates its own distance vector.
> >
> > A link-state protocol, on the other hand, keeps a database of
> > routers and
> > their links and needs to run Dijstra's algorithm to find the
> > shortest path.

Except that I wouldn't go as far as to say that it "needs to run Dijkstra's
algorithm". I don't think it needs to, it just happens to be the most
efficient so everyone is using that.

Thanks,

Zsombor
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