R0106-HP MSR Router Series MPLS Command Reference(V7)

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Usage guidelines
LDP nonstop routing (NSR) backs up protocol states and data (including LDP session and LSP information)
from the active process to the standby process. After the LDP primary process fails, the backup process
seamlessly takes over the job of the primary process. The LDP peers are not aware of the LDP interruption
and keep the LDP session in Operational state, so the forwarding is not interrupted.
The LDP primary process fails when one of the following events occurs:
• The primary process restarts.
• The MPU where the primary process resides fails.
• The MPU where the primary process resides performs an ISSU.
• An active/standby process switchover occurs when the position determined by process placement
is different from the position where the process operates.
Both LDP NSR and LDP GR ensure continuous traffic forwarding. Choose either feature as needed. They
have the following differences:
• Device requirements—To use LDP NSR, the device must have two or more MPUs, and the primary
and backup process for LDP reside on different MPUs. To use LDP GR, the device can have only one
MPU on the device.
• LDP peer requirements—With LDP NSR, LDP peers of the local device are not aware of any
switchover events on the local device. The local device does not require the help of a peer to restore
the MPLS forwarding information. With LDP GR, the LDP peer must be able to identify the GR
capability flag (in the Initialization message) of the GR restarter, and the LDP peer acts as a GR
helper to help the GR restarter to restore MPLS forwarding information.
Example
# Enable LDP NSR.
<Sysname> system-view
[Sysname] mpls ldp
[Sysname-ldp] non-stop-routing
Related commands
• display mpls ldp discovery
• display mpls ldp fec
• display mpls ldp peer
• display mpls ldp summary
pv-limit
Use pv-limit to specify the path vector limit.
Use undo pv-limit to restore the default.
Syntax
pv-limit pv-number
undo pv-limit
Default
The path vector limit is 32.