helper-only

Specifies that the LSR acts as a helper only for LDP graceful restart (GR).

Syntax

helper-only
no helper-only

Command Default

Full LDP GR mode with the router acting either as a restarting router or a GR helper.

Modes

MPLS LDP GR configuration mode

Usage Guidelines

A GR helper is an LSR whose neighbor is restarting its LDP component.

In helper mode, a router does not preserve its forwarding entries on a LDP GR restart. It indicates to its peers that forwarding state is not preserved by sending an initialization message with the Reconnect Time and the Recovery Time set to zero (0) in FT session TLV. The configuration commands for reconnect-time and recovery-time are rejected with informational messages. However, it can help a neighboring router recover its forwarding entries when the neighbor is going through restart.

The no form of the command removes the LDP GR helper mode and revert back to full LDP GR mode with the router acting either as a restarting router or a GR helper.

MPLS is supported on the Extreme 8820, SLX 9740, SLX 9640, and SLX 9540 devices only.

Examples

The following example configures the LSR for LDP GR helper mode only.

device# configure terminal
device(config)# router mpls
device(config-router-mpls)# ldp
device(config-router-mpls-ldp)# graceful-restart
device(config-router-mpls-ldp-gr)# helper-only