Ospf Effects On Graceful Restart And Network Stability During Unified Issu; Configuring Graceful Restart Before Unified Issu Begins - Juniper SERVICE AVAILABILITY - CONFIGURATION GUIDE V 11.1.X Configuration Manual

JUNOSe 11.1.x Service Availability Configuration Guide
See Specifying the Number of Retransmission Attempts.
When the unified ISSU operation attempts to verify the upgrade prerequisites, a
warning message is generated if any tunnels are present for which failover
resynchronization is disabled.
You can use the show l2tp tunnel failover-resync disable command to identify the
tunnels referred to by the warning message. The command enables filtering based
upon the effective failover resynchronization mechanism:
If a successful failover resynchronization cannot be performed for a tunnel following
the upgrade, then the tunnel and all of its sessions are subject to disconnection.
L2TP automatically detects a peer L2TP disconnect after the unified in-service software
upgrade is completed by detecting a control channel failure.
When peer LNSs are not configured with PPP keepalives or inactivity timeouts, you
must configure an inactivity timeout for L2TP on the LAC. This timeout enables the
router to detect a PPP disconnect when signaling has been dropped during the unified
ISSU forwarding interruption. In the absence of this configuration, the connection
at the LAC and LNS is left as logged in for an extended period of time following the
upgrade.
Related Topics

OSPF Effects on Graceful Restart and Network Stability During Unified ISSU

OSPF has the following issues to consider before you begin a unified in-service
software upgrade:

Configuring Graceful Restart Before Unified ISSU Begins

You must configure OSPF graceful restart before you begin the unified in-service
software upgrade. When the unified ISSU process verifies the upgrade requirements
during the initialization phase, it detects whether graceful restart is configured. If it
is not configured, the CLI displays a warning message and prompts you to proceed
or halt. You can stop at this point to configure graceful restart.
If instead you proceed, the unified in-service software upgrade can complete
successfully, but the OSPF neighbors are likely to break the adjacencies with the
upgrading router and consider that routes formerly reached through this router are
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OSPF Effects on Graceful Restart and Network Stability During Unified ISSU
host1#show l2tp tunnel failover-resync disable
L2TP tunnel 2/1 is Up with 1 active session
1 L2TP tunnel found
Application Support for Unified ISSU on page 71
Graceful restart Required
Dead interval Required
Routing around the upgrading router Optional