Hey Gods Son

Both BGP and RIP are application layer protocols using TCP 179 and UDP 520 respectively for communication. OSPF and EIGRP are network layer protocols using protocol number 89 and 88 respectively for communication. If you were to enable rip on a router, capture and inspect the updates as they leave or arrive, you will get a better understanding as to why rip is an application layer protocol. Hope that helps see file attached.

Peace

Kenard,

I don't think it is that straightforward.  Many consider BGP an application that happens to affect the routing table.  Most people consider RIP, EIGRP, and OSPF routing protocols.  There are also those that would consider BGP a routing protocol as opposed to an application that affects the routing table.  I will say that BGP is much closer to being an application than the others, in my opinion.  Now there is code attached to sockets in the case of all four of these examples.  Does that mean they should all be considered applications?  You are correct in that that EIGRP and OSPF run directly on top of IP.  So if you look at it in a sniffer, you see an IP Protocol id of 88 or 89 respectively and then the EIGRP or OSPF header.  In the case of RIP and BGP, there is a layer 4 header between the IP Header and the Routing Protocol header.

The question I have is why would you consider BGP and RIP application layer protocols while considering EIGRP and OSPF Network Layer protocols?  I would think that if you consider RIP as an application layer protocol, all of those examples would be considered application layer protocols.  RIP and BGP certainly ride on top of layer 4.  EIGRP and OSPF ride on top of layer 3.  EIGRP even has it own transport layer defined as RTP.  So the transport layer is sort of built in. 

If some one asked me, I would describe these as follows--

EIGRP is transported by layer 3

OSPF is transported by layer 3

RIP is transported by layer 4

BGP is an application that transports routing information at layer 4

The good thing about these OSI model discussions is that it really doesn't matter (except for possibly on a test).  The model is to help us get our minds around how a network operates.  I think everyone here is succeeding at that.  In my experience, the examples given on the test has less ambiguity than the examples that are thrown out on this forum.

Hi Sergei

Did you read what others had posted on this thread?

Regards Conwyn

I did but I don't see anything wrong with what I said.

But all four protocols affect the network layer.  I can see how it can be confusing.

RIP and OSPF operate at layer 7

OSPF and EIGRP operate at layer 3 

the only reason which I can see at this point is the RIP operates on UDP port 520 ant BGP operates on TCP Port 179 but they still support l-3 functionality a lot rather than Layer 7

Sorry man the last part is difficult to answer

Regards,

Diwakar

Hi

• IS-IS runs over the data link layer (layer 2 )
  
• OSPF, IGRP, and EIGRP run directly over IP (layer 3) But  OSPF and EIGRP have their own reliable transmission mechanism while IGRP assumed an unreliable transport
  
• RIP runs over UDP (layer 4) .
  
• BGP runs over TCP (layer 4) .