Performing an In Service Software Upgrade
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 feature information and caveats, see 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 for Performing an XE ISSU" section.
Use Cisco Feature Navigator to find information about platform support and Cisco IOS XE Software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Contents
•Information About Performing an ISSU
•Configuration Examples for Performing an ISSU
•Feature Information for Performing an XE ISSU
Information About Performing an ISSU
•ISSU and the Cisco ASR 1000 Series Router
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 RP.
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.
Figure 1 shows the ISSU states during the ISSU process.
Figure 1 ISSU States During the ISSU Process

ISSU and the Cisco ASR 1000 Series Router
See the 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 "In Service Software Upgrade (ISSU)" module in the Cisco ASR 1000 Series Aggregation Services Routers Software Configuration Guide.
Configuration Examples for Performing an ISSU
•Example: Verifying Redundancy Mode Before Beginning the ISSU Process
•Example: Verifying the ISSU State
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.
Router# dir harddisk:
Directory of harddisk:/
11 drwx 16384 Jul 24 2008 15:04:47 +00:00 lost+found
1114113 drwx 65536 Nov 25 2008 16:58:36 +00:00 tracelogs
294913 drwx 4096 Jul 24 2008 15:14:39 +00:00 core
12 -rw- 225308932 Nov 12 2008 15:50:37 +00:00 asr1000rp1-adventerprisek9.02.02.00.122-33.XNB-20080810_010002-mcp_dev_2.bin
13 -rw- 209227980 Aug 20 2008 17:31:59 +00:00 asr1000special
14 -rw- 222240972 Sep 8 2008 17:13:22 +00:00 rp_super.ppc.bin
15 -rw- 209985740 Nov 25 2008 16:50:39 +00:00 asr1000rp1-adventerprisek9.02.01.02.122-33.XNA2.bin
39313059840 bytes total (38439649280 bytes free)
Router# dir stby-harddisk:
Directory of stby-harddisk:/
11 drwx 16384 Jul 24 2008 15:05:35 +00:00 lost+found
1507329 drwx 73728 Nov 25 2008 16:58:50 +00:00 tracelogs
2424833 drwx 4096 Jul 24 2008 15:22:04 +00:00 core
12 -rw- 225308932 Sep 8 2008 04:48:39 +00:00 asr1000rp1-adventerprisek9.02.02.00.122-33.XNB-20080810_010002-mcp_dev_2.bin
13 -rw- 209227980 Aug 20 2008 17:41:21 +00:00 asr1000special
14 -rw- 222240972 Sep 8 2008 18:04:26 +00:00 rp_super.ppc.bin
15 -rw- 209985740 Nov 25 2008 16:55:11 +00:00 asr1000rp1-adventerprisek9.02.01.02.122-33.XNA2.bin
39313059840 bytes total (38438928384 bytes free)
Additional References
Related Documents
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Cisco IOS commands |
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Cisco IOS High Availability commands |
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FHRP and HSRP group shutdown |
`Configuring HSRP" chapter of the Cisco IOS XE IP Application Services Configuration Guide |
ISSU on the Cisco ASR 1000 Series Routers |
"In Service Software Upgrades" chapter of the Cisco ASR 1000 Series Aggregation Services Routers Software Configuration Guide |
VRRP |
"Configuring VRRP" chapter in the Cisco IOS XE IP Application Services Configuration Guide |
Standards
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No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature. |
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MIBs
RFCs
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No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature. |
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Technical Assistance
Feature Information for Performing an XE ISSU
Table 1 lists the features in this module and provides links to specific configuration information.
Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Note Table 1 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.