(Optional) Configuring Timers for a Local LDP Session

Timers of a local LDP session include the link Hello hold timer, link Hello send timer, Keepalive hold timer, Keepalive send timer, and Exponential backoff timer.

Context

The following timers are used in a local LDP session:

**Table 1** Timers for a local LDP session
LDP Timers	Description	Suggestion
Link Hello send timer	Used to send Hello messages periodically to notify a peer LSR of the local LSR's presence and establish a Hello adjacency. Similar to a remote LDP session, a local LDP session uses a link Hello send timer.	On an unstable network, decrease the value of a link Hello send timer, speeding up network fault detection.
Link Hello hold timer	Used to exchange Hello messages periodically between two LDP peers to maintain the Hello adjacency. If no Hello message is received after the link Hello hold timer expires, the Hello adjacency is torn down. Similar to a remote LDP session, a local LDP session uses a link Hello hold timer.	On a network with unstable links or a large number of packets, increase the value of the link Hello hold timer, preventing a local LDP session from being torn down and set up frequently.
KeepAlive send timer	Used to send KeepAlive messages periodically, maintaining the local LDP session.	On an unstable network, set a smaller value for a KeepAlive send timer, speeding up network fault detection.
KeepAlive hold timer	Used to send LDP PDUs over an LDP session, maintaining the local LDP session. If no LDP PDU is received after the KeepAlive hold timer expires, the TCP connection is closed and the local LDP session is terminated.	On a network with unstable links, increase the value of the KeepAlive hold timer, preventing the local LDP session from flapping.
Exponential backoff timer	Started by an LSR that plays an active role after an LDP Initialization message sent by the LSR to another LSR that plays a passive role fails to be processed or parameters carried in the message are rejected. The LSP that plays the active role periodically resends an LDP Initialization message to initiate an LDP session before the Exponential backoff timer expires.	When a device is upgraded, prolong the period for the active role to retry setting up a session. In this case, you can set larger initial and maximum values for the Exponential backoff timer. When a device that bears services tends to alternate between Up and Down, shorten the period for the active role to retry setting up a session. In this case, you can set smaller initial and maximum values for the Exponential backoff timer.

The default timer values are recommended.

Procedure

Configure a link Hello send timer.
1. Run system-view
  The system view is displayed.
2. Run interface interface-type interface-number
  The view of the interface on which an LDP session is to be established is displayed.
3. Run mpls ldp timer hello-send interval
  A link Hello send timer is configured.
  
  Effective link Hello send timer value = Min{Configured link Hello send timer value, 1/3 of the link Hello hold timer value}
4. Run commit
  The configuration is committed.
Configure a link Hello hold timer.
1. Run system-view
  The system view is displayed.
2. Run interface interface-type interface-number
  The view of the interface on which an LDP session is to be established is displayed.
3. Run mpls ldp timer hello-hold interval
  A link Hello hold timer is configured.
  
  If a link Hello hold timer is configured on each end of a local LDP session, the smaller value takes effect.
4. Run commit
  The configuration is committed.
Configure a Keepalive send timer for a local LDP session.
1. Run system-view
  The system view is displayed.
2. Run interface interface-type interface-number
  The view of the interface on which an LDP session is to be established is displayed.
3. Run mpls ldp timer keepalive-send interval
  A Keepalive send timer is configured for the local LDP session.
  
  Effective Keepalive send timer value = Min{Configured Keepalive send timer value, 1/3 of the Keepalive hold timer value}
4. Run commit
  The configuration is committed.
Configure a Keepalive hold timer for a local LDP session.
1. Run system-view
  The system view is displayed.
2. Run interface interface-type interface-number
  The view of the interface on which an LDP session is to be established is displayed.
3. Run mpls ldp timer keepalive-hold interval
  A Keepalive hold timer is configured for the local LDP session.
  
  If a Keepalive hold timer is configured on each end of a local LDP session, the smaller value takes effect.
4. Run commit
  The configuration is committed.
Configure an Exponential backoff timer.
1. Run system-view
  The system view is displayed.
2. Run mpls
  The MPLS view is displayed.
3. Run mpls ldp
  The MPLS-LDP view is displayed.
4. Run backoff timer init max
  An Exponential backoff timer is configured.
5. Run commit
  The configuration is committed.