BGP Protocol Learning Notes

BGP (Border Gateway Protocol) Border Gateway Protocol, is an external routing protocol, which refers to the boundary of an autonomous system, Used to propagate routing information between autonomous systems BGP constructs a topology diagram of an autonomous system by adding the as path and other accompanying attribute information to the routing information to eliminate the policy of user configuration implemented by the routing loop.

The focus is on choosing the best route and controlling the propagation of the route, rather than discovering and computing the route.

The BGP protocol uses link-oriented TCP as its transport layer protocol, which increases the reliability of the protocol and the port number is 179.

BGP is a path vector routing protocol that transmits routing information between autonomous systems, and BGP propagates the entire routing table when it is started, and then propagates only the part of the network change. Support for classless inter-domain routing.

BGP has 4 message types

1. Open: Used to identify yourself

2. Keepalive:

3. Update: Updating routing information

4. Notification: Notice when the error is checked

Two kinds of neighbors: EBGP, IBGP

Routing notification principle: BGP informs all Neighbors (EBGP, IBGP) of the received EBGP message;

The IBGP message received will no longer be advertised to the IBGP neighbor.

Generally only the best route that you know is communicated to the neighbor, and the optimal route that you know is added to the routing table.

Message format:

Message header + Newspaper style

BGP Protocol Learning Notes