Is-Is Effects On Graceful Restart And Network Stability During Unified Issu; Configuring Graceful Restart Before Unified Issu Begins; Configuring Graceful Restart When Bgp And Ldp Are Configured - Juniper SERVICE AVAILABILITY - CONFIGURATION GUIDE V 11.1.X Configuration Manual

JUNOSe 11.1.x Service Availability Configuration Guide
New FTP connections are not allowed and all existing FTP connections are dropped
after the unified ISSU process begins. Also, no remote file operations are allowed
while unified ISSU is in progress. If unified ISSU is aborted, FTP server is returned
to the state in which it was before unified ISSU was started.
Related Topics

IS-IS Effects on Graceful Restart and Network Stability During Unified ISSU

IS-IS 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 IS-IS graceful restart on the router and on all IS-IS neighbors
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 IS-IS neighbors are likely to break the adjacencies with the
upgrading router and consider that routes formerly reached through this router are
now unreachable. When the unified in-service software upgrade completes and the
routing protocols restart, the IS-IS neighbors can relearn the routes through the router.
When you issue the issu start command, IS-IS lengthens its hello timer values and
sends LSPs with the new values. The upgrade proceeds when the IS-IS neighbors
have acknowledged the new values.

Configuring Graceful Restart When BGP and LDP Are Configured

When BGP, IS-IS, and LDP are all configured on a router on which you want to perform
a unified in-service software upgrade, ensure that the IS-IS graceful restart timeout
is longer than the LDP graceful restart timeout. The IS-IS graceful restart does not
complete when the LDP graceful restart timeout is longer than the IS-IS graceful
restart timeout. Configure IS-IS graceful timeout with the nsf t3 command. Configure
LDP graceful restart timeout with the mpls ldp graceful-restart timers max-recovery
command.
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IS-IS Effects on Graceful Restart and Network Stability During Unified ISSU

Application Support for Unified ISSU on page 71
Graceful restart Required
Routing around the upgrading router Optional