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Software Requirements for Unified ISSU
The following requirements must be met for traffic forwarding to continue. However,
failing to meet these requirements does not halt the unified ISSU operation. The
unified ISSU process offers the option to override or ignore these forwarding
requirements.
The running JUNOSe Software release must support unified ISSU.
You can upgrade to a software version that supports unified ISSU from a software
version that does not support unified ISSU only by means of a conventional
upgrade. During the conventional upgrade, all line modules are reloaded, all
subscribers are dropped, and traffic forwarding is interrupted until the upgrade
is completed.
The armed (upgrade) release must be capable of being upgraded to from the
currently running release; it must be higher-numbered than the running release.
All applications that are configured on the router must support unified ISSU and
stateful SRP switchover.
If one or more unified ISSU-challenged applications are configured and you
proceed with a unified in-service software upgrade, the unified ISSU process
forces a conventional upgrade on the router. All line modules are reloaded, all
subscribers are dropped, and traffic forwarding is interrupted until the upgrade
is completed.
You can avoid this circumstance by removing the configuration for the unified
ISSU-challenged applications from the router before you begin the in-service
software upgrade.
Stateful SRP switchover must be configured on the router. Use the following
commands to configure high availability:
host1(config)#redundancy
host1(config-redundancy)#mode high-availability
See "Managing Stateful SRP Switchover" on page 25 for information about high
availability.
Graceful restart must be enabled for all configured routing protocols. The unified
ISSU operation relies on graceful restart to keep the routing protocols alive through
the various stages of the upgrade.
All connected peers must be configured with graceful restart. Because some
protocols cannot themselves confirm peer configuration for graceful restart, you
must ensure that the peers are properly configured.
For applications that exchange keepalive messages with peers, you must ensure
that the poll times are adequate to maintain the peering session across any
forwarding interruption caused by the unified ISSU operation.
On the ERX1440 router, you must enter the key provided with your license in
order to make the unified ISSU CLI commands available. Unified ISSU is licensed
on only the ERX1440 router; no license is required or available on the E120 and
E320 routers.
Chapter 4: Configuring a Unified In-Service Software Upgrade
Software Requirements for Unified ISSU
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