Hold Time

Hold Time
The Hold Time field is 2 bytes long and informs the receiving BGP speaker of the proposed
value for the holdtime by the sending BGP speaker. The receiving BGP speaker calculates the
lowest of its configured holdtime and the value in the Hold Time field. This will determine the number
of seconds the BGP speaker will allow between the receipt of KEEPALIVE and/or UPDATE messages.
If one of these messages is not received in the time specified by the holdtime, the neighbor is
considered dead. Each time one of the messages is received, the holdtime is reset to 0.
Unlike the negotiation for the BGP version, where a connection is reset to negotiate a common
version number, the negotiation for the holdtime does not reset the connection.
The BGP speakers can set the value for the holdtime to 0. If this occurs, no KEEPALIVE
messages are sent. This means that the connection will always be up. Having a holdtime of
0 could cause problems if one side of the connection has a loss of communications. Because
KEEPALIVE messages are not being exchanged, the other side of the connection would
never know the loss of communication occurred. If the value of the Hold Time field is not
0, it must then be at least 3.