Routing protocols confusion

A question arises while reading about socket programming, So far I have read routing protocols such RIP,OSPF,eBGP and iBGP. Where RIP and OSPF does work inside an autonomous system, And for 开发者_如何学Goconnectivity of two different autonomous system we are using eBGP. But it says iBGP works inside an autonomous system as well,

so,

Is iBGP protocol is same as RIP and OSPF?

Thanks in advance for any clarification,

Krio

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I think that iBGP serves the same purpose as the other interior routing protocols like RIP and OSPF. But feature and functionalists associated with each protocol differ. RIP and BGP is a distance vector routing protocol where as OSPF is link state routing protocol. The metric used for calculating the path cost is different is each protocol. RIP used hop count, OSPF uses bandwidth and BGP uses next hop, administrative weights, local preference, route origin, path length, origin code, metric, and other attributes.

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When you talk about routing protocols, you can think about they are providing a way to enable the routers to calculate the route for specific object(packet, cell, services etc.) while delivery them from the source to the target.

Specifically, for the object to be routed, they carrying information such as source,target,size, Class of Service (CoS).

For router, it carrying information such as interface type, connectivity to other routers. And the network as a whole, which covering the topology information over which the specific object is to be routed.

To make the routing process happen, the router make decision about how to route a packet. The decision is based on the knowledge of the network reachability information.

To build up the reachability informaiton, the router needs to talk with each other to communicate how they connected with the other routers.

What you talk to the other router, how you talk to the other routers, and which type of router should you talk to, and how the routers make routing decision based on these information form the basis of the routing protocols.

For large network, to make it admin-able, the network is furthered grouped into different hierarchies, such as Autonomos System (AS), Areas, sub Area.

Now come to your question,

iBGP different from the OSPF and RIP in how they distribute the routing informaiton and the type of information they distributed, and also how they calculate and make routing decisions.

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RIP, OSPF and BGP work completely different. Although purpose is same, finding new routes and building network topology. These are dynamic routing protocols. However principals used are quite different. No iBGP is not as same as RIP or OSPF. major difference is BGP establishes the tcp connection for exchanging information, where as Rip uses UDP and ospf itself is separate protocol whose value is 89 in the protocol filed of ip packet. As soon as backbone or boundary router establishes the connection with other autonomous system, after receiving advertisement, it creates and another tcp session within routes inside AS. RIP uses distance vector protocol. RIP guess the distance between it and next hop using metrics. OSPF using link state protocol. Each router checks the connectivity with other router in topology there by covering entire topology. Now it plots the graph and apply dijkstra's shortest distance algorithm. Now here is what iBGP does, since the backbone router has already has routes to all routers in its AS, which was found with help of RIP, OSPF now it will initiate tcp connection with the routers in AS though port 179. Now it's upto AS, to enable routers to accept or block port 179. If they don't BGP works else not.

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RIP and OSPF are used to distribute internal prefixes, i.e. to teach every router in the AS how to reach the other routers in the same AS.

IGBP is used to distribute external prefixes, i.e. once one AS-border router has learned how to reach an external prefix (using EBGP), IBGP is used to distribute this information to the other AS-border routers in the same AS.