Configuring BGP4+ Connection Parameters

Usage Scenario

BGP4+ can use various timers to minimize the impact of interface flapping or route flapping.

• Timers for BGP4+ Peers

  After establishing a BGP4+ connection, two peers periodically send Keepalive messages to each other to detect the status of the BGP4+ peer relationship. If the router does not receive any Keepalive message or any other type of packets from its peer within a time of period called holdtime period, it considers the BGP4+ connection closed.

  When establishing a BGP4+ connection, two peers compare their holdtime periods and use the shorter one. If the used holdtime period is 0, no Keepalive message will be transmitted and the hold timer status will not be detected.

  

  If the timeout period of the hold timer changes, the BGP4+ connection may be interrupted for a short period of time. This is because the peers need to renegotiate the holdtime period.

• BGP4+ ConnectRetry Timer

  After BGP4+ initiates a TCP connection, the ConnectRetry timer will be stopped if the TCP connection is established successfully. If the first attempt to establish a TCP connection fails, BGP4+ re-establishes the TCP connection after the ConnectRetry timer expires.

  Setting a short ConnectRetry interval reduces the period BGP4+ waits between attempts to establish a TCP connection, which speeds up the establishment of the TCP connection.

  Setting a long connectRetry interval suppresses routing flapping caused by peer relationship flapping.

Pre-configuration Tasks

Before configuring BGP4+ connection parameters, configure basic BGP4+ functions.