>>"Deloso, Elmer G." wrote:
>> > When comparing Distance Vector with Link State protocols, although the
>> > procedures are different,
>> > isn't the end result for both the same? That is, having a complete map
>> > of the entire network?
>> > Please correct me if I'm missing something. Thanks.
>
>
>It's a good question that I'd like to see some gurus discuss.
>
>I think people lose sight of the fact that the end result is quite similar.
Obviously, lots of issues are involved here. But one of the first I'd
mention is that in well-designed networks of any appreciable size,
whether they use LS or DV dynamic routing or static routing, the
individual routers do NOT have a "complete map of the entire
network." The network is divided into a hierarchy of areas/domains,
and each router has a map of its own domain and routes that leave the
domain.
Even a "default-free" BGP router with a "full" 80,000 plus route
table does not have a complete routing table for the network. It does
not, and should not, know the internal details of other autonomous
systems.
Distance vector and link state are basic routing ideas, but, as
presented for RIP and basic OSPF, are certainly not the most advanced
evolution of routing.
Routing stability is a major issue in the Internet.
There are theoretical arguments that in principle, distance vector is
less resource intensive than a link state model of a network of the
same size, and is less vulnerable to the effects of incorrect routing
information. Link state, however, generally offers faster
convergence to non-adjacent destinations within the domain.
And, indeed, there may be multiple RIBs in a complex situation, such as VPNs.
>
>The differences between distance vector and link-state have to do
>with how the RIB gets populated. These differences are based on what
>data is sent to broadcast/multicast addresses and neighbors, and how
>the received data is analyzed and placed into the RIB.
>
>The data that ends up in a RIB also depends on such routing protocol
>features as:
>
>* metric: how does the protocol decide between multiple paths?
>* load balancing: should the protocol remember more than one path?
>* does the protocol support route summarization?
>* does the protocol support areas?
>* should intra-area routes be preferred over inter-area routes, such
>as in OSPF?
>* are routes being filtered?
>* ETC.
>
>The real answer is, read Howard's book on routing and switching! ;-)
>
>Priscilla
"What Problem are you trying to solve?"
***send Cisco questions to the list, so all can benefit -- not
directly to me***
Howard C. Berkowitz [EMAIL PROTECTED]
Technical Director, CertificationZone.com
Senior Product Manager, Carrier Packet Solutions, NortelNetworks (for ID only)
but Cisco stockholder!
"retired" Certified Cisco Systems Instructor (CID) #93005
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