Huawei AR1200 Series - Optional) Configuring an LDP Label Advertisement Mode

Procedure
Step 1 Run:
system-view
The system view is displayed.
Step 2 Run:
mpls
The MPLS view is displayed.
Step 3 Run:
label advertise { explicit-null | implicit-null | non-null }
The label allocated to the LSR at the penultimate hop is configured. One of the following
parameters can be configured in this command:
l implicit-null: is the default value and means that PHP is supported. If this parameter is
configured, the egress allocates an implicit null label with the value of 3 to the LSR at the
penultimate hop.
l explicit-null: means that PHP is not supported. If this parameter is configured, the egress
allocates an explicit null label with the value of 0 to the LSR at the penultimate hop. The
explicit-null parameter can be configured when MPLS QoS attributes are used.
l non-null: means that PHP is not supported. If this parameter is configured, the egress
allocates a common label with a value greater than or equal to 16 to the LSR at the penultimate
hop.
Exercise caution when using the explicit-null or non-null parameter. The setting leads to a great
deal of resource consumption on the egress.
NOTE
PHP takes effect on LSPs that will be established after PHP is configured.
----End
2.5.4 (Optional) Configuring an LDP Label Advertisement Mode
An LDP label advertisement mode can be configured to control LSP establishment.
Context
A downstream LSR sends a Label Mapping message to an upstream LSR in downstream
unsolicited mode (DU) by default. This allows multiple LSPs including backup LSPs to be
established. If a network fault occurs, services rapidly switch to a backup LSP, improving
network reliability. Establishing a large number of LSPs burdens an LSR such as a digital
subscriber link access multiplexer (DSLAM) that is a low-performance access device deployed
on an MPLS network. On a large-scale network, a DSLAM can be configured to send Label
Mapping messages to only upstream LSRs only after receiving requests for labels. This
minimizes the number of unwanted MPLS forwarding entries forwarded by the DSLAM.
Procedure
l Configuring an LDP Label Advertisement Mode of local LDP session.
1. Run:
Huawei AR1200 Series Enterprise Routers
Configuration Guide - MPLS 2 MPLS LDP Configuration
Issue 01 (2011-12-30) Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
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