At 07:05 AM 9/25/01, you wrote:
>hmm..
>that's tricky, as I remember BGP used TCP for the routing update.
RIP runs on top of UDP, so you would have to make the same argument for
RIP, but it's not a good argument. Characterizing what layer they are at by
what layer they reside on doesn't work.
We could claim that all the routing protocols except IS-IS (which runs
directly on top of LLC) are upper-layer protocols since they run on top of
IP, but that doesn't work either. Theoretically they don't have to run on
top of IP. They don't use IP's method for forwarding traffic across an
internetwork. Every routing protocol packet I have ever seen has a TTL of
1. EIGRP can propagate queries, but that's not forwarding based on
network-layer addresses. OSPF propagates Link State Updates, but that's not
forwarding based on network-layer addresses either. Routing protocol
packets are send to other routers on the same segment as either unicasts,
broadcasts, or multicasts.
Obviously, I have heard the argument before about routing protocols running
at the application layer and there's some logic to it, as there is logic to
characterizing the layer by what layers are below it, but it's just not
based on reality regarding the definitions by ISO for their OSI reference
model.
The function of the network layer is forwarding packets across an
internetwork and learning how to reach networks in the internetwork
(routing protocols). The function of the application layer is providing
services to end-user applications, such as e-mail, Telnet, Web browsing.
By the way, with 7-layer bean dip, if you put the beans on top and the
lettuce on the bottom, do the beans become lettuce and vice versa? ;-)
Priscilla
>The only thing I can think of functionaly perhaps it's on layer 3, but
>interm of BGP itself, perhaps it's an application residing most certainly
>not in network layer.
>
>donny
>
>
>>From: "Priscilla Oppenheimer"
>>Reply-To: "Priscilla Oppenheimer"
>>To: [EMAIL PROTECTED]
>>Subject: Re: which layer do the ospf bgp rip work on [7:20953]
>>Date: Mon, 24 Sep 2001 23:27:16 -0400
>>
>>Network layer. Routing is a fundamental component of the network layer.
>>
>>At 10:14 PM 9/24/01, lhill peng wrote:
>> >which layer do the routing protocol such as ospf rip bgp eigrp work on?
>> >sb said that they are on application, others on network
>> >what is the right answer??
>>________________________
>>
>>Priscilla Oppenheimer
>>http://www.priscilla.com
>_________________________________________________________________
>Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp
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________________________
Priscilla Oppenheimer
http://www.priscilla.com
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