The unified in-service software upgrade (ISSU) feature enables you to upgrade between two different Junos OS releases with no disruption on the control plane and with minimal disruption of traffic.
NOT:Unified ISSU is supported only on dual Routing Engine platforms.
NOT:In addition, the graceful Routing Engine switchover (GRES) and nonstop active routing (NSR) features must be enabled.
Checks are made for the following:
- Disk space is available for the /var file system on both Routing Engines.
- The configuration is supported by a unified ISSU.
- The PICs are supported by a unified ISSU.
- Graceful Routing Engine switchover is enabled.
- Nonstop active routing is enabled.
set routing-options nonstop-routing
set system commit synchronize
show task replication
request routing-engine login re1
show system switchover
show chassis in-service-upgrade
show chassis hardware