Router Behavior During A Unified In-Service Software Upgrade; Unified Issu Platform Considerations; Hardware And Software Requirements Before Beginning A Unified Issu - Juniper SERVICE AVAILABILITY - CONFIGURATION GUIDE V 11.1.X Configuration Manual

Applications that do not support unified ISSU applications cannot maintain state and
configuration with minimal traffic loss across the upgrade to a higher-numbered
release. When you attempt a unified in-service software upgrade on a router on
which a unified ISSU-challenged application is configured, the unified in-service
software upgrade cannot proceed. You must unconfigure the unified ISSU-challenged
application to successfully perform the unified ISSU.

Router Behavior During a Unified In-Service Software Upgrade

The following behaviors are characteristic of a unified in-service software upgrade.
Related Topics

Unified ISSU Platform Considerations

Unified ISSU is supported on E120 and E320 routers. Unified ISSU is also supported
on the ERX1440 router with the SRP-40G PLUS with 2GB of memory. Unified ISSU
on the ERX1440 requires a license key.
Connections that were established before you begin the unified ISSU are
maintained across the upgrade. Any such connection that was forwarding data
continues to do so during and after the upgrade.
New connections are denied until the upgrade is completed.
Packet loss during the upgrade is limited. Bandwidth through the modules is
reduced, but the impact is minimal.
Graceful restart protocols do not time out during the unified ISSU.
The unified in-service software upgrade has a minimal effect on the control and
data planes. During the SRP module upgrade phase, forwarding through the
fabric is interrupted for about 1 second on the E120 and E320 routers and about
4 seconds on the ERX1440 Broadband Services Router. During the line module
upgrade phase, forwarding through the chassis is interrupted for about 15 seconds
on the E120 and E320 routers and for about 50 seconds on the ERX1440 router.
Diagnostic software is not run on any modules during a unified in-service software
upgrade.
The router undergoes a cold restart if you attempt to upgrade the software to a
lower-numbered version with unified ISSU. The unified in-service software
upgrade must be to a higher-numbered release than the running release.
Additional memory is consumed during a unified in-service software upgrade.
Available memory on a line module might not be sufficient due to the module's
configuration. Unified ISSU can detect this limitation during the upgrade procedure
and exit the process, gracefully.
Unified ISSU Phases Overview on page 63
Application Support for Unified ISSU on page 71
Hardware and Software Requirements Before Beginning a Unified ISSU on
page 60
Upgrading Router Software with Unified ISSU on page 96
Chapter 4: Configuring a Unified In-Service Software Upgrade

Unified ISSU Platform Considerations

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