outbound peer split-horizon

Function

The outbound peer split-horizon command enables split horizon on an LSR to allow the LSR to distribute labels only to its upstream LDP peers.

The undo outbound peer split-horizon command restores the default setting.

By default, split horizon is not enabled, which means that an LSR distributes labels to both upstream and downstream LDP peers.

Format

outbound peer { peer-id | all } split-horizon

undo outbound peer { peer-id | all } split-horizon

Parameters

Parameter	Description	Value
peer-id	Specifies the LSR ID of an LDP peer.	The value is in dotted decimal notation.
all	Indicates all LDP peers.	-

Views

MPLS-LDP view

Default Level

2: Configuration level

Usage Guidelines

Usage Scenario

An LSR sends Label Mapping messages to both upstream and downstream LDP peers by default, speeding up LDP LSP convergence. This leads to the establishment of a great number of unwanted LSPs, wasting resources. To reduce the number of LSPs and saving memory resources, run the outbound peer { peer-id | all } split-horizon command to configure an LDP split horizon policy, enabling the LSR to send Label Mapping messages only to upstream LDP peers.

In the outbound peer split-horizon command, configure either of the following parameters to prevent an LSR from distributing labels to specified downstream peers:

peer-id: prevents the LSR from distributing labels to a specified downstream peer.
all: prevents the LSR from distributing labels to all downstream peers.

Prerequisites

MPLS LDP has been enabled globally using the mpls ldp command in the system view.

Precautions

The all parameter takes preference over the peer-id parameter. For example, the outbound peer all split-horizon and then outbound peer 2.2.2.2 split-horizon commands are run, the outbound peer all split-horizon command can be saved in the configuration file and take effect, not the outbound peer 2.2.2.2 split-horizon command.

Example

# Enable split horizon for all LDP peers.

<HUAWEI> system-view
[HUAWEI] mpls ldp
[HUAWEI-mpls-ldp] outbound peer all split-horizon