H3C Technologies H3C S10500 Series Switches - Manual (Page 72)

61
NOTE:
•
When specifying the type of label for an egress to distribute to a penultimate hop, check whether the
penultimate hop supports PHP. If the penultimate hop supports PHP, you can configure the egress to
distribute an explicit null or implicit null label to the penultimate hop. If the penultimate hop does not
support PHP, you must configure the egress to distribute a normal label.
• The device supports PHP when it works as a penultimate hop.
• For LDP sessions existing before the label advertise command is configured, you must reset the LDP
sessions by using the reset mpls ldp command for the PHP configuration to take effect.
Configuring the policy for triggering LSP establishment
You can configure an LSP triggering policy on an LSR, so that only routes matching the policy can trigger
establishment of LSPs, reducing the number of LSPs to be established on the LSR and avoiding instability
of the LSR caused by excessive LSPs.
An LSR supports the following types of LSP triggering policies:
• Allowing all routing entries to trigger establishment of LSPs.
• Filtering routing entries by an IP prefix list, so static and IGP routes denied by the IP prefix list will not
trigger LSP establishment. To use this policy, you must create the IP prefix list. For information about
IP prefix list configuration, see Layer 3—IP Routing Configuration Guide.
Follow these steps to configure the policy for triggering LSP establishment:
To do… Use the command… Remarks
Enter system view system-view —
Enter MPLS view mpls —
Configure the LSP establishment
triggering policy
lsp-trigger [ vpn-instance
vpn-instance-name ] { all | ip-prefix
prefix-name }
Optional
By default, only host routes with
32-bit masks can trigger
establishment of LSPs.
NOTE:
•
For an LSP to be established, an exactly matching routing entry must exist on the LSR. For example, on
an LSR, to establish an LSP to a loopback address with a 32-bit mask, there must be an exactly matching
host routing entry on the LSR.
• If the vpn-instance vpn-instance-name option is specified, the command configures an LSP
establishment triggering policy for the specified VPN. Otherwise, the command configures an LSP
establishment triggering policy for the public network routes.
Configuring the label distribution control mode
With the label re-advertisement function enabled, an LSR periodically looks for FECs not assigned with
labels, assigns labels to them if any, and advertises the label-FEC bindings. You can set the label
re-advertisement interval as needed.
Follow these steps to configure the LDP label distribution control mode: