Howard..........What can I say...It's posts like this that keep me reading
this list!!! Very well said...
"Howard C. Berkowitz" <[EMAIL PROTECTED]> wrote in message
news:v0422083ab56575ac4454@[63.216.127.98]...
> >"Winchester, Derek S." <[EMAIL PROTECTED]> asked,
>
>
>
> >Looking for an educated answer other than the book definitions that
explain
> >Convergence in Eigrp: What feature or why is Convergence in Eigrp faster
> >than other Link-state and distance vector protocols. I would like it in
the
> >words that actually makes sense. I know that it is faster, and I know
that
> >Dual makes convergence simpler and fast, but in words of the common man,
> >WHY?
>
>
> It's misleading to say EIGRP is faster, unless you compare it to
> other modern protocols with the same hello timer value. By default,
> EIGRP has a 5 second hello timer while OSPF and ISIS have 10 seconds.
> Obviously, a protocol with a shorter hello timer will detect and
> respond faster to changes.
>
> Once the hello timers are equated, will EIGRP, OSPF or ISIS be the
> fairest in the land? The mirror on the wall says, "it depends."
>
> Tony Li, who used to be one of the principal routing developers at
> Cisco, and is coauthor of BGP, discussed this a while back in one of
> the IETF mailing lists, and described EIGRP as faster to converge
> when the alternate path was in an adjacent router or one that is one
> hop away from the adjacent router, while OSPF is faster when finding
> the new path will involve routers more than one or two hops away.
>
> The reality is that in most circumstances, there is very difference
> among the real-world convergence times of the three modern IGPs. If
> you were doing something such as non-local-acknowledged SNA, which
> has critical convergence time requirements, you'd have to tune the
> timers of any of them.
>
> EIGRP probably needs less resources, but needs more tuning for low
> speed lines (below 56 Kbps, roughly)
>
> RIP and IGRP, however, are significantly slower than the modern
> protocols, principally because they (1) have to wait for periodic
> updates and (2) usually have holddown timers that make them wait for
> several updates.
>
> There is a whole other issue, however, on what do we mean by
> convergence? I'm in the process of writing an Internet Draft on some
> definitions, especially for BGP.
>
> Is convergence:
>
> The time it takes a router to initialize its routing table on power
on?
> The time it takes to be able to route to a new (i.e., previously
> unknown) destination, after it receives the update? After the change
> causing the update occurs?
> The time it takes after it recognizes the best route to a
> destination is down, but it has an alternate route in local memory?
> The time it takes after it recognizes the best route to a
> destination is down, but it does not have an alternate route in local
> memory?
>
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