LDP Hello Hold time

The LDP hold time specifies how long the device or MPLS interface waits for its LDP peers to send a Hello message.

When the device does not receive a Hello message within this time, the LDP session with the peer can be terminated. The device includes the hold time in the Hello messages it sends out to its LDP peers. The LDP Hold time sent in Hello messages to adjacent LSRs can be configured globally for either Link or Targeted LDP sessions.

For an MPLS interface, how long it waits for its LDP peers to send a Hello message differs for a targeted LDP session and a link LDP session, as follows:

• For targeted LDP sessions—The value received in Hello messages from its peers determines the time that the device waits for its LDP peers to send a Hello message. When the timeout value received from a peer is zero, the Hold time is set to the default period of 45 seconds.
• For link LDP sessions —In this case, the wait time is determined by any one of the following criteria.
  • When the Hello hold time is set per-interface, that value is used.
  • When the Hello hold time is not set per-interface, the hold time in the received message is used.
  • When the Hello hold time in the received message is zero (0), the default value of 15 seconds is used.