mldp make-before-break

Function

The mldp make-before-break command enables the mLDP make-before-break (MBB) capability.

The undo mldp make-before-break command disables the mLDP MBB capability.

By default, the mLDP MBB capability is disabled.

Format

mldp make-before-break

undo mldp make-before-break

Parameters

None

Views

MPLS-LDP view

Default Level

2: Configuration level

Task Name and Operations

Task Name	Operations
mpls-ldp	write

Usage Guidelines

Usage Scenario

If the optimal route between a non-root node and a root node on an mLDP P2MP network changes, the non-root node re-selects an upstream node and by default tears down the P2MP LSP. As a result, traffic is dropped before a new P2MP LSP is established. To minimize traffic loss, run the mldp make-before-break command to enable the mLDP MBB capability on each node on the mLDP P2MP network. If the optimal route to the root node changes, the non-root node establishes a new P2MP LSP before tearing down the original P2MP LSP.

Prerequisites

mLDP P2MP has been enabled globally using the mldp p2mp command.

Precautions

Deploying the MBB may fail to ensure switching performance if a node to switch traffic is notified by the upstream node of the successful establishment of a new path whereas connectivity the forwarding plane fails. This situation occurs when an overloaded node resides on a path after convergence and this node cannot ensure the consistency between the control and forwarding planes during MBB-compliance protocol interaction.

Example

# Enable the mLDP make-before-break capability.

<HUAWEI> system-view
[~HUAWEI] mpls
[*HUAWEI-mpls] quit
[*HUAWEI] mpls ldp
[*HUAWEI-mpls-ldp] mldp p2mp
[*HUAWEI-mpls-ldp] mldp make-before-break