Details Of Session Protection - Cisco NCS 5500 Series Configuration Manual

Implementing MPLS Label Distribution Protocol
peer was able to restore its state successfully. It reinstates the corresponding forwarding state entries and
receives binding from the restarting peer. When the recovery timer expires, any forwarding state that is still
marked as stale is deleted.
If the restarting LSR fails to recover (restart), the restarting LSR forwarding state and entries will eventually
timeout and is deleted, while neighbor-related forwarding states or entries are removed by the Peer LSR on
expiration of the reconnect or recovery timers.

Details of Session Protection

LDP session protection lets you configure LDP to automatically protect sessions with all or a given set of
peers (as specified by peer-acl). When configured, LDP initiates backup targeted hellos automatically for
neighbors for which primary link adjacencies already exist. These backup targeted hellos maintain LDP
sessions when primary link adjacencies go down.
The Session Protection figure illustrates LDP session protection between neighbors R1 and R3. The primary
link adjacency between R1 and R3 is directly connected link and the backup; targeted adjacency is maintained
between R1 and R3. If the direct link fails, LDP link adjacency is destroyed, but the session is kept up and
running using targeted hello adjacency (through R2). When the direct link comes back up, there is no change
in the LDP session state and LDP can converge quickly and begin forwarding MPLS traffic.
Figure 5: Session Protection
When LDP session protection is activated (upon link failure), protection is maintained for an unlimited
Note
period time.
MPLS Configuration Guide for Cisco NCS 5500 Series Routers, IOS XR Release 6.2.x
Details of Session Protection
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