This module describes the In Service Software Upgrade (ISSU) process and provides configuration examples for ISSU on Cisco
ASR 1000 Series routers.
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest caveats and feature information,
see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module,
and to see a list of the releases in which each feature is supported, see the feature information table.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature
Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Information About Performing an ISSU
ISSU Process Overview
ISSU allows Cisco software to be upgraded or downgraded, at a router level, while the system continues to forward packets.
ISSU takes advantage of the Cisco high availability infrastructure--Cisco NSF with SSO and hardware redundancy--and eliminates
downtime associated with software upgrades or version changes by allowing updates while the system remains in service. Cisco
high availability features combine to lower the impact that planned maintenance activities have on network service availability,
with the results of less downtime and better access to critical systems.
SSO mode supports configuration synchronization. When images on the active and standby RPs are different, this feature allows
the two Route Processors (RPs) to remain synchronized although they may support different sets of commands.
An ISSU-capable router consists of two RPs (active and standby) and one or more line cards. Before initiating the ISSU process,
you must copy the Cisco IOS software into the file systems of both RPs
After you have copied the Cisco IOS software to both file systems, load the new version of Cisco IOS software onto the standby
After switchover, the standby RP takes over as the new active RP.
Then, the former active RP, which is now the new standby RP, is loaded with the new software.
The two RPs in a system can be in one of three different states during ISSU:
Active--One RP is actively forwarding packets with old software. After the ISSU process is performed, the original active
RP becomes the standby RP.
Standby--Perform ISSU on the standby RP, loading it with new software. After the ISSU process is performed, the original
standby RP is the new active RP.
Hot standby--After the original standby RP becomes the new active RP, load the new software image into the new standby RP.
Doing so makes the standby RP a hot standby RP.
The figure below shows the ISSU states during the ISSU process.
ISSU and the Cisco ASR 1000 Series Router
Cisco ASR 1000 Series Aggregation Services Routers Software Configuration Guide for information about ISSU and Cisco ASR 1000 Series routers.
How to Perform an ISSU
Unlike SSO, which is a mode of operation for the device and a prerequisite for performing ISSU, the ISSU process is a series
of steps performed while the router or switch is in operation. The steps result in the implementation of new or modified Cisco
software, and have a minimal impact to traffic.
For information on performing Cisco IOS XE ISSU upgrades on the Cisco ASR 1000 Series Router, see the “Software Upgrade Process” section in theCisco ASR 1000 Series Aggregation Services Routers Software Configuration Guide.
Configuration Examples for Performing an ISSU
Example Verifying Redundancy Mode Before Beginning the ISSU Process
The following examples display verification that the system is in SSO mode and that slot R0 is the active RP1 and slot R1
is the standby RP1. Both RPs are running the same Cisco IOS XE Software image.
Router# show redundancy states
my state = 13 -ACTIVE
peer state = 8 -STANDBY HOT
Mode = Duplex
Unit ID = 48
Redundancy Mode (Operational) = sso
Redundancy Mode (Configured) = sso
Redundancy State = sso
Maintenance Mode = Disabled
Manual Swact = enabled
Communications = Up
client count = 67
client_notification_TMR = 30000 milliseconds
RF debug mask = 0x0
Router# show platform
Chassis type: ASR1006
Slot Type State Insert time (ago)
--------- ------------------- --------------------- -----------------
0 ASR1000-SIP10 ok 02:48:56
0/0 SPA-2X1GE-V2 ok 02:46:38
0/1 SPA-2XOC3-POS ok 02:46:38
R0 ASR1000-RP1 ok, active 02:48:56
R1 ASR1000-RP1 ok, standby 02:48:56
F0 ASR1000-ESP10 ok, active 02:48:56
F1 ASR1000-ESP10 ok, standby 02:48:56
P0 ASR1006-PWR-AC ok 02:47:55
P1 ASR1006-PWR-AC ok 02:47:55
Slot CPLD Version Firmware Version
--------- ------------------- ---------------------------------------
0 07091401 12.2(33r)XN2
R0 07062111 12.2(33r)XN2
R1 07062111 12.2(33r)XN2
F0 07051680 12.2(33r)XN2
F1 07051680 12.2(33r)XN2
Example Verifying the ISSU State
The following example displays and verifies the ISSU state:
Router# show issu state detail
--- Starting installation state synchronization ---
Finished installation state synchronization
No ISSU operation is in progress
The new version of the Cisco IOS XE Software must be present on both of the RPs. The directory information displayed for each
of the RPs shows that the new version is present.
No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature.
The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and
resolving technical issues with Cisco products and technologies.
To receive security and technical information about your products, you can subscribe to various services, such as the Product
Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds.
Access to most tools on the Cisco Support website requires a Cisco.com user ID and password.
The following table provides release information about the feature or features described in this module. This table lists
only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise,
subsequent releases of that software release train also support that feature.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco
Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Table 1. Feature Information for Performing an ISSU
In Service Software Upgrade (ISSU)
Cisco IOS XE Release 2.1
The following features were introduced:
Dual IOS processes on the same RP
In Service Software Upgrade (ISSU)
ISSU - ARP
ISSU - Frame Relay
ISSU - GLBPv6
ISSU - HSRPv6
ISSU - HDLC
ISSU - IGMP snooping
ISSU - IPv6 uRPF
ISSU - IS-IS
ISSU - Managed LNS MPLS
ISSU - MLD Access Group
ISSU - NAT
ISSU - PPP/MLP
ISSU - QoS
ISSU - SNMP
The following commands were introduced or modified
ISSU - ATM
Cisco IOS XE Release 2.3
This feature was introduced.
ISSU - HSRPv6 on VRF interfaces
Cisco IOS XE Release 3.1S
This feature was introduced for Cisco ASR 1000 Series Aggregation Services Routers.