NOTE: You must have an advanced features license to use BGP routing.
Border Gateway Protocol (BGP) contains two distinct subsets: internal BGP (iBGP) and external BGP (eBGP). iBGP is intended for use within your own networks. eBGP is used to connect many different networks together and is the main routing protocol for the Internet backbone. FortiSwitch units support iBGP, and eBGP only for communities.
BGP was first used in 1989. The current version, BGP-4, was released in 1995 and is defined in RFC 1771. That RFC has since been replaced by RFC 4271. The main benefits of BGP-4 are classless inter-domain routing and aggregate routes. BGP is the only routing protocol to use TCP for a transport protocol. Other routing protocols use UDP.
BGP makes routing decisions based on path, network policies, and rulesets instead of the hop-count metric as RIP does, or cost-factor metrics as OSPF does.
BGP is the routing protocol used on the Internet. It was designed to replace the old Exterior Gateway Protocol (EGP) which had been around since 1982, and was very limited. BGP enabled more networks to take part in the Internet backbone to effectively decentralize it and make the Internet more robust, and less dependent on a single ISP or backbone network.
This section covers the following topics: