Topic starter
BGP (Border Gateway Protocol) messages are used for communication between BGP peers to manage the exchange of routing information. There are four main types of BGP messages:
1. OPEN Message
- Purpose: Establishes a BGP session between peers.
- Contents: Includes information such as BGP version, AS number, hold time, BGP router ID, and optional parameters.
- Usage: Sent when a BGP session is first initiated to establish parameters and capabilities between the peers.
2. UPDATE Message
- Purpose: Advertises new routes or withdraws previously advertised routes.
- Contents: Includes information about network prefixes (NLRI—Network Layer Reachability Information), path attributes (like AS Path, Next Hop, Local Preference), and withdrawals (routes that are no longer reachable).
- Usage: Sent to update the routing table with new routes or to remove routes that are no longer valid.
3. NOTIFICATION Message
- Purpose: Reports errors and is used to close the BGP session.
- Contents: Includes an error code and subcode, which provide details about the error condition that occurred.
- Usage: Sent when a protocol error is detected or when a BGP session needs to be terminated.
4. KEEPALIVE Message
- Purpose: Maintains the BGP session and ensures that the connection between peers is still active.
- Contents: This message does not carry routing information; it is simply a keep-alive mechanism.
- Usage: Sent periodically between peers to prevent the session from timing out and to confirm that the peer is still reachable.
Summary
- OPEN: To establish the BGP session.
- UPDATE: To advertise or withdraw routes.
- NOTIFICATION: To report errors and close the session.
- KEEPALIVE: To maintain the session and confirm peer reachability.
Posted : 14/09/2024 8:02 pm
