Configuring The Cisco Ios Xe In Service Software Upgrade Process - Cisco Catalyst 4500 series Administration Manual

Prerequisites to Performing ISSU
Related Documents
Related Topic
Performing ISSU
Information about Cisco Nonstop Forwarding
Information about Stateful Switchover
Prerequisites to Performing ISSU
Before performing ISSU, you must meet these prerequisites:
•
Note
•
•
•
Software Configuration Guide—Release IOS XE 3.6.0SG and IOS 15.2(2)SG
7-2
A permanent "ISSU barrier" exists between pre-IOS XE 3.6.0E and IOS XE 3.6.0 releases: ISSU is
supported between versions on the same side of the barrier but it is not supported between versions
on opposite sides.
This restriction applies to Catalyst 4500X in a VSS, as well as to Supervisor Engine 7E,
Supervisor Engine 7LE, and Supervisor Engine 8E in a VSS or in a redundant chassis.
Four scenarios will illustrate the restriction:
If you are running a release prior to IOS XE 3.6.0E (3.5.1E, for example), you cannot perform
an ISSU upgrade to IOS XE 3.6.0E.
If you are running IOS XE 3.6.0E, you cannot perform an ISSU downgrade to IOS XE 3.5.0E.
If you are running IOS XE 3.6.0E, you can perform an ISSU upgrade to IOS XE 3.6.1E (when
released).
If you are running a release after IOS XE 3.6.0E (for example, 3.7.0, when released), you cannot
perform an ISSU downgrade to IOS XE 3.5.0E.
The type of the existing and target image must match. You cannot upgrade from a Universal Lite
image to a Universal image (and vice versa) without experiencing several minutes of traffic loss. The
same restriction applies between crypto and non-crypto images.
The active and the standby supervisor engines must have the same supervisor engine hardware (same
model, same memory, and so on).
The new and old Cisco IOS XE software images must be loaded into the file systems (bootflash, SD
card, or USB) of both the active and the standby supervisor engines before you begin the ISSU
process.
The old software image should be available either in bootflash, SD card, or USB and the system
should have been booted from one of these locations because the boot variable must be changed
before the ISSU process starts.
Chapter 7

Configuring the Cisco IOS XE In Service Software Upgrade Process

Document Title
Cisco IOS Software: Guide to Performing In Service Software
Upgrades
Cisco Nonstop Forwarding
http://www.cisco.com/en/US/docs/ios/12_2s/feature/guide/fsnsf20s.
html
Stateful Switchover
http://www.cisco.com/en/US/docs/ios/12_0s/feature/guide/sso120s.
html
OL-30933-01