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Configuring the Hello Message Attributes for the LMP Control Channel

Hello messages are exchanged between LMP peers to maintain the control channel after LMP has activated the control channel. The LMP control channel is considered to be up only when the hello negotiation is successful. Successful negotiation consists of the local peer sending a hello message to the remote peer and receiving a hello message in response.

The LMP peers continue to exchange hello messages after the LMP control channel is up in order to maintain the channel.

The hello interval specifies the interval between periodic hello messages. The hello dead interval specifies how long the local peer waits for a hello response before it declares the LMP control channel to be down. When the channel goes down, the local peer restarts the LMP control channel negotiation and configuration process.

You can specify a hello interval from 150 through 300,000 milliseconds. The default hello interval is 150 milliseconds.

You can specify a hello dead interval from 500 through 300,000 milliseconds. The default hello dead interval is 500 milliseconds.

To configure the attributes for hello messages exchanged between LMP peers, include the hello-interval and hello-dead-interval statements:




hello-interval milliseconds;

hello-dead-interval milliseconds;

You can configure these statements at the following hierarchy levels:

[edit protocols link-management peer peer-name lmp-protocol]
[edit logical-systems logical-system-name protocols link-management peer peer-name lmp-protocol]

When an LMP control channel comes up after a successful exchange of hello messages between LMP peers, LMP uses link property correlation to verify the traffic engineering and data link information on both sides of a link. To do so, the local peer sends a LinkSummary message for each traffic engineering link governed by the LMP control channel. The LinkSummary message contains information that characterizes the traffic engineering link and each data link in the traffic engineering link.

The local peer continues sending a LinkSummary message for each link until the remote peer responds with a LinkSummaryAck message or until the message retry limit is reached. When the message retry limit is reached, the local peer logs that event and restarts the link property correlation process.

When the remote peer receives a LinkSummary message, it examines its own link information. If this information agrees with that in the LinkSummary message, the remote peer responds with a LinkSummaryAck message. If the information is different, the remote peer responds with a LinkSummaryNack message.

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