Ospf 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; Configuring A Longer Dead Interval Than Normal - Juniper JUNOSE SOFTWARE FOR E SERIES 11.3.X - SERVICE AVAILABILITY CONFIGURATION GUIDE 2010-10-08 Configuration Manual

JunosE 11.3.x Service Availability Configuration Guide

OSPF 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

Configuring a Longer Dead Interval Than Normal

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OSPF has the following issues to consider before you begin a unified in-service software
upgrade:
Graceful restart—Required
Dead interval—Required
Routing around the upgrading router—Optional
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 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.
You must also ensure that the OSPF neighbors have been configured as graceful restart
helper routers. During the unified ISSU initialization phase, OSPF graceful restart on the
upgrading router cannot verify whether its neighbors are helper routers, and reports that
fact by means of the CLI.
When BGP, LDP, and OSPF are all configured on a router on which you want to perform
a unified in-service software upgrade, ensure that the OSPF graceful restart timeout is
longer than the LDP graceful restart timeout. The OSPF graceful restart does not complete
when the LDP graceful restart timeout is longer than the OSPF graceful restart timeout.
Configure OSPF graceful restart timeout with the graceful-restart restart-time command.
Configure LDP graceful restart timeout with the mpls ldp graceful-restart timers
max-recovery command.
To prevent OSPF from timing out to the OSPF neighbors, you must configure a dead
interval that is longer than the expected forwarding outage for the platform. During the
initialization phase, unified ISSU displays the recommended dead interval in a warning
message. For information about the expected forwarding outage, see "Interruption in
Traffic Forwarding for Layer 3 Routing Protocols During Unified ISSU" on page 135
Copyright © 2010, Juniper Networks, Inc.