.1. Border Gateway Protocol BGP
BGP is an autonomous system routing protocol, which is used to exchange routing information between ASs, and is usually used between operators and operators or between enterprises and operators. BGP-4 is currently widely used, supports CIDR, and the BGP protocol uses TCP179 port for transmission. The protocol transmitted between routes in the same AS is called IBGP, and the protocol transmitted between routes in different ASs is called EBGP. BGP adopts an incremental update strategy and does not periodically synchronize routes.
Autonomous system (autonomous system), the manager of a segment of Internet IP addresses, or ISP (Internet Service Provider). In the autonomous system, the administrator can independently decide all routing operations, access between autonomous systems, and exchange information through external routing protocols such as BGP. The ISP that provides Internet services must be registered and assigned an AS number, which is unique on the entire network, and the AS number manager in China is the China Internet Network Information Center (cnnic).
Peer (peer), BGP connection is a one-to-one connection, the two parties who establish a BGP connection are called peers, peers are identified by AS number, the same AS number is called an internal peer, using the IBGP protocol, different The AS number is called an external peer, and EBGP is used.
In BGP, Transmission Control Protocol is used. It is a type of mesh topology or design. It consists of two independent networks (autonomous systems or ASs) exchanging routing information. Two routers agree to exchange information about how to reach a particular IP range. BGP uses Transmission Control Protocol (TCP) port 179.
BGP protocol features:
- BGP stands for Border Gateway Protocol;
- BGP applies to the best path algorithm;
- It is basically used in larger organizations compared to EIGRP;
- BGP is a vector state type;
- BGP is the Exterior Gateway Protocol;
- BGP is a more intelligent than EIGRP