xFSU reduces the traffic downtime during software reload or upgrade operations.
The traffic downtime is reduced for software upgrade operations, when compared to Fast Software Upgrade. The reduced traffic
downtime depends on the switch configuration, the current release, and the intended release for upgrade.
The following table provides information between the traffic downtime, the current release, and the intended release.
|
From
|
To
|
Traffic Downtime
|
|
Cisco IOS XE 17.15.2
|
any supported future release
|
is less than 5 seconds.
|
| Cisco IOS XE Amsterdam 17.3.2a |
any supported release upto Cisco IOS XE 17.15.2
|
is less than 30 seconds.
|
xFSU uses graceful restart capability (also known as Cisco NSF) to ensure that switch configurations, such as certain routing
protocols, remain unaffected during a software upgrade or reload.

Note
|
xFSU works on access layer switches only.
|
Perpetual Power over Ethernet (PoE), if configured, continues to provide uninterrupted power to the connected devices during
software reload or upgrade.