Why we use BGP?
GBP (Border Gateway Protocol) is mostly used by ISPs (internet service providers). BGP is replaced with the older protocol that is EGP and latest version of BGP is Version 4. BGP v4 is defined in RFC 1771 you can read that for more detail. BGP suppose to be a distance vector protocol, it metric is hop count but hop count in BGP case is a autonomous system therefore BGP is also know as path vector protocol.
As a routing protocol BGP is best choice in following environment:
- BGP is normally use for connecting different AS’s, in an environment where your autonomous system have multiple links to other AS’s.
- BGP is better option in transit AS, it mean that you can allow your packets packet to move through from one AS to other AS, for Example LAN to an ISP.
- BGP is build for controlling the large networks, it will work great if you have a large amount of traffic and traffic needs high degree of control.
- The multiprotocol version of BGP is used to carry MPLS VPN information between all provider edge (PE) routers within a VPN community. MP-BGP is defined in RFC 2858. It introduces a new BGP capabilities advertisement to determine whether a BGP peer supports MP-BGP.
- You can handle the Policy-based routing with BGP among different AS. There two types of BGP that are IBGP and EBGP, you can use the IBGP in internal or in single AS, while EBGP is used among different AS.