Ldp Nsr - HP MSR2000 Configuration Manual

3. After LDP completes restart, the GR restarter reestablishes an LDP session to the GR helper. If the
LDP session is not set up before the Reconnect timer expires, the GR helper deletes the stale
FEC-label mappings and the corresponding MPLS forwarding entries. If the LDP session is
successfully set up before the Reconnect timer expires, the GR restarter sends the remaining time of
the MPLS Forwarding State Holding timer as the LDP Recovery time to the GR helper.
4. After the LDP session is reestablished, the GR helper starts the LDP Recovery timer.
5. The GR restarter and the GR helper exchange label mappings and update their MPLS forwarding
tables.
The GR restarter compares each received label mapping against stale MPLS forwarding entries. If
a match is found, the restarter deletes the stale mark for the matching entry. Otherwise, it adds a
new entry for the label mapping.
The GR helper compares each received label mapping against stale FEC-label mappings. If a
match is found, the helper deletes the stale mark for the matching mapping. Otherwise, it adds the
received FEC-label mapping and a new MPLS forwarding entry for the mapping.
6. When the MPLS Forwarding State Holding timer expires, the GR restarter deletes all stale MPLS
forwarding entries.
7. When the LDP Recovery timer expires, the GR helper deletes all stale FEC-label mappings.

LDP NSR

The following matrix shows the feature and hardware compatibility:
Hardware
MSR2000
MSR3000
MSR4000
LDP nonstop routing (NSR) backs up protocol states and data (including LDP session and LSP information)
from the active process to the standby process. When the LDP primary process fails, the backup process
seamlessly takes over primary processing. The LDP peers are not notified of the LDP interruption. The LDP
peers keep the LDP session in Operational state, and the forwarding is not interrupted.
The LDP primary process fails when one of the following occurs:
The primary process restarts.
•
The MPU where the primary process resides fails.
•
• The MPU where the primary process resides performs an ISSU.
The LDP process' position determined by the process placement function is different from the
•
position where the LDP process is operating.
Choose either LDP NSR or LDP GR to ensure continuous traffic forwarding:
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
•
LDP NSR compatibility
No
No
Yes
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