Supported Platforms
Configuring the LDP Timer for Hello Messages
LDP hello messages enable LDP nodes to discover one another and to detect the failure of a neighbor or the link to the neighbor. Hello messages are sent periodically on all interfaces where LDP is enabled.
There are two types of LDP hello messages:
- Link hello messages—Sent through the LDP interface as UDP packets addressed to the LDP discovery port. Receipt of an LDP link hello message on an interface identifies an adjacency with the LDP peer router.
- Targeted hello messages—Sent as UDP packets addressed to the LDP discovery port at a specific address. Targeted hello messages are used to support LDP sessions between routers that are not directly connected. A targeted router determines whether to respond or ignore a targeted hello message. A targeted router that chooses to respond does so by periodically sending targeted hello messages back to the initiating router.
By default, LDP sends hello messages every 5 seconds for link hello messages and every 15 seconds for targeted hello messages. You can configure the LDP timer to alter how often both types of hello messages are sent. However, you cannot configure a time for the LDP timer that is greater than the LDP hold time. For more information, see Configuring the Delay Before LDP Neighbors Are Considered Down.
Configuring the LDP Timer for Link Hello Messages
To modify how often LDP sends link hello messages, specify a new link hello message interval for the LDP timer using the hello-interval statement:
For a list of hierarchy levels at which you can include this statement, see the statement summary section for this statement.
Configuring the LDP Timer for Targeted Hello Messages
To modify how often LDP sends targeted hello messages, specify a new targeted hello message interval for the LDP timer by configuring the hello-interval statement as an option for the targeted-hello statement:
For a list of hierarchy levels at which you can include these statements, see the statement summary sections for these statements.
