Miscellaneous 

Why do we use BGP instead of OSPF?

Joe Ford

Why do we use BGP instead of OSPF?

BGP is considered to be more flexible as well as scalable than OSPF and it would be also used on a larger network. OSPF would be used to determine the fastest route whereas the BGP would be putting emphasis on determining the best path. Well, Because OSPF stub areas which would be a total mess to configure.

Can I use BGP instead of any IGP?

IGP means Interior Routing Protocol, and EGP – Exterior Routing Protocol. OSPF, IS-IS, RIP and EIGRP are IGP Protocols. BGP is the only available EGP Protocol. There is no need to use the same IGP protocol in these three networks.

Why is IGP used in BGP?

Scalability: You use BGP because you don't want to carry your entire internet routing table in your IGP (i.e. in my case, OSPF)… Countermeasures have now been implemented in IGP protocols (like this one for OSPF in IOS) to prevent redistribution from BGP into OSPF from causing a major outage.

Why is BGP needed?

The main advantage of BGP is that it gives you much more control over what routes you advertise and what advertisements you accept from your neighbors. BGP gives you more control over route selection and your neighbor's route selection. That's one of the major reasons BGP is The Routing Protocol for the Internet.

What is the difference between Ibgp and Ebgp?

EBGP is peering between two different AS, whereas IBGP is between same AS (Autonomous System). 2. Routes learned from eBGP peer will be advertised to other peers (BGP or IBGP); however, routes learned from IBGP peer will not be advertised to other IBGP peers. Multihop is the term used in EBGP only.

Why we use Ibgp instead of IGP?

As with everything there are trade offs; the scalability, control, and flexibility you get from iBGP means that it's a slower converging protocol than IGPs (in general).

Why does Ibgp need full mesh?

IBGP requires a full mesh of BGP peers. The full mesh of IBGP routers is needed because IBGP routers do not re-advertise routes learned via IBGP to other IBGP peers. External BGP (EBGP) relies on the autonomous system path to prevent loops.