Table Of Contents
Cisco IOS XE In Service Software Upgrade Process
Prerequisites for Performing the Cisco IOS XE ISSU Process
Restrictions for Performing the Cisco IOS XE ISSU Process
Information About Performing the Cisco IOS XE ISSU Process
ISSU Rollback Timer Overview on the Cisco ASR 1000 Series Router
ISSU with Dual IOS Processes on a Single RP Overview
Overview of Stateful Switchover
Versioning Capability in Cisco IOS XE Software to Support ISSU
ISSU-Capable Protocols and Applications
How to Perform the Cisco IOS XE ISSU Process
Configuration Examples for Performing the Cisco IOS XE ISSU Process
Verifying Redundancy Mode Before Beginning the ISSU Process: Example
Verifying the ISSU State: Example
Feature Information for Performing the Cisco IOS XE ISSU Process
Cisco IOS XE In Service Software Upgrade Process
First Published: March 16, 2006Last Updated: November 25, 2009The Cisco IOS XE In Service Software Upgrade (ISSU) process allows Cisco IOS XE Software to be updated or otherwise modified while packet forwarding continues. In most networks, planned software upgrades are a significant cause of downtime. ISSU allows Cisco IOS XE Software to be modified while packet forwarding continues, which increases network availability and reduces downtime caused by planned software upgrades. This document provides information about ISSU concepts and describes the steps taken to perform ISSU in a system.
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 the Cisco IOS XE ISSU Process" 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
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Prerequisites for Performing the Cisco IOS XE ISSU Process
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Prerequisites for Performing the Cisco IOS XE ISSU Process
This section describes the prerequisites for performing the Cisco IOS XE ISSU process:
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Restrictions for Performing the Cisco IOS XE ISSU Process
This section describes restrictions for performing ISSU.
General Restrictions
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Cisco ASR 1000 Series Aggregation Services Routers Restrictions
For information on ISSU restrictions between hardware and software configurations on the Cisco ASR 1000 Series Router, see the Cisco ASR 1000 Series Aggregation Services Routers Software Configuration Guide.
Information About Performing the Cisco IOS XE ISSU Process
Before you perform ISSU, you should understand the following concepts:
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ISSU Process Overview
The ISSU process allows software to be updated or otherwise modified while packet forwarding continues with minimal interruption.
For the Cisco ASR 1000 Series Routers, ISSU-compatibility depends on the software sub-package being upgraded and the hardware configuration. Consolidated packages are ISSU-compatible in dual RP configurations only and have other limitations described in the Cisco ASR 1000 Series Aggregation Services Routers Software Configuration Guide.
Some RP and ESP software sub-packages can be upgraded using ISSU even in single RP or ESP hardware configurations via dual IOS processes running on the RP; others require dual RP or ESP configurations for an ISSU upgrade. The SPA and SIP software sub-packages must be upgraded on a per-SPA or per-SIP basis. See Table 1 to view an ISSU table that addresses the contexts where limited interruption upgrades can be performed.
If you are updating multiple sub-packages, you should also realize that the sequence of the upgrade is important to minimize router downtime for the software upgrade (see the "Using ISSU to Upgrade Sub-Packages (Pre Cisco IOS XE Release 2.1.2)" section in the Cisco ASR 1000 Series Aggregation Services Routers Software Configuration Guide).
The Cisco ASR 1000 Series Routers are designed to run one version of Cisco IOS XE Software for all consolidated packages and sub-packages on an RP, and running sub-packages from different versions of Cisco IOS XE Software can cause unexpected router behavior.
When performing ISSU upgrades on the Cisco ASR 1000 Series Routers, it is important to remember that minimal interruption upgrades can be performed using either the issu command set or the request platform command set, and that either command set can be used to perform limited interruption individual consolidated package or sub-package upgrades.
Table 1 provides a list of the Cisco ASR 1000 Series Routers sub-packages and whether or not they can be upgraded without losing any network traffic in single and dual RP and ESP configurations using ISSU.
Table 1 Limited Interruption Upgrade Compatibility Table
Consolidated package (any)
No (Reload required)
Yes (RP switchover)
RPBase
No (RP Reload required)
Yes (RP switchover)
RPControl
Yes (in-service)
Yes (in-service)
RPAccess
Yes (in-service)
Yes (in-service)
RPIOS
Yes1 (IOS software switchover)
Yes (RP switchover)
ESPBase
No2 (ESP reload required)
Yes3 (via ESP switchover)
SIPBase4
No (SPAs in SIP do not forward traffic during upgrade)
No (SPAs in SIP do not forward traffic during upgrade)
SIPSPA5
No (SPAs in SIP do not forward traffic during upgrade)
No (SPAs in SIP do not forward traffic during upgrade)
1 Only supported if software redundancy is configured on the RP.
2 ESP has to reload to complete ESPBase sub-package upgrade. All router traffic will be lost during ESP upgrade.
3 An ESP switchover occurs as part of the upgrade, so traffic is forwarded with minimal interruption.
4 Any SIPBase upgrade will require the SPA interfaces to go down during the upgrade for all the SPAs in the SIP.
5 Any SIPSPA upgrade will require the SPA interfaces for that particular SPA to go down during the upgrade.
ISSU Rollback Timer Overview on the Cisco ASR 1000 Series Router
The Cisco ASR 1000 Series Router ISSU procedure has a rollback timer. Rollback timers are used for for ISSU procedures on all Cisco routers that support ISSU. This section provides a brief overview of ISSU rollback timers on the Cisco ASR 1000 Series Routers.
During ISSU, the rollback timer begins after the consolidated package or sub-package is loaded. If the upgrade does not move forward in the amount of time specified in the rollback timer, the configuration will automatically "roll back" to the previous configuration and the ISSU upgrade will be cancelled.
Upgrades using the issu command set and the request platform command set both have the rollback timer option. The issu command set always uses a rollback timer; the request platform command set does not use a rollback timer unless the auto-rollback option is used in the request platform software package install command line.
For the issu command set, the issu acceptversion command can be entered to stop the rollback timer without committing the upgrade during the ISSU upgrade. The issu commitversion command can be entered to stop the rollback timer and commit the ISSU upgrade.
For the request platform command set, the request platform software package install rp slot commit command must be entered to stop the rollback timer only in cases where the auto-rollback option is used.
The rollback timer for the issu command set can be configured by entering the issu set rollback-timer command. The rollback timer when used with the request platform command set is specified when you use the auto-rollback option when entering the issu request platform software package install command.
For ISSU upgrades on Cisco ASR 1000 Series Routers, it may be advisable to set long rollback times when the upgrade is being performed on routers with large configurations.
The amount of time left on the rollback timer during an ISSU upgrade can be checked by entering the show issu rollback-timer command.
ISSU with Dual IOS Processes on a Single RP Overview
To complete an ISSU upgrade of an individual sub-package using dual IOS processes on a single RP, RPR or SSO must first be enabled.
ISSU with dual IOS processes is useful for upgrading the individual RP sub-packages that can be upgraded without a router reload. See Table 1 for a list of these sub-packages. Most sub-package upgrades in a single RP configuration require a hardware reload to complete (whether an RP reload for an RP sub-package, an ESP reload for the ESPBase sub-package, a SIP reload for a SIPBase sub-package, or a SPA reload for the SIPSPA sub-package), so limited interruption upgrades for single RP configurations are not available in most upgrade scenarios.
Overview of Stateful Switchover
Development of the SSO feature is an incremental step within an overall program to improve the availability of networks constructed with Cisco IOS XE routers.
In specific Cisco networking devices that support dual RPs, SSO takes advantage of RP redundancy to increase network availability by establishing one of the RPs as the active processor while the other RP is designated as the standby processor, and then synchronizing critical state information between them. Following an initial synchronization between the two processors, SSO dynamically maintains RP state information between them. A switchover from the active to the standby processor occurs when the active RP fails, is removed from the networking device, or is manually taken down for maintenance. The Cisco 1000 ASR Series Routers also support dual IOS processes on a single RP to provide SSO capability.
Cisco NSF is used with SSO. Cisco NSF allows for the forwarding of data packets to continue along known routes while the routing protocol information is being restored following a switchover. With Cisco NSF, peer networking devices do not experience routing flaps, thereby reducing loss of service outages for customers.
Figure 1 illustrates how SSO is typically deployed in service provider networks. In this example, Cisco NSF with SSO is enabled at the access layer (edge) of the service provider network. A fault at this point could result in loss of service for enterprise customers requiring access to the service provider network.
For Cisco NSF protocols that require neighboring devices to participate in Cisco NSF, Cisco NSF-aware software images must be installed on those neighboring distribution layer devices. Depending on your objectives, you may decide to deploy Cisco NSF and SSO features at the core layer of your network. Doing this can help reduce the time to restore network capacity and service for certain failures, which leads to additional availability.
Figure 1 Cisco NSF with SSO Network Deployment: Service Provider Networks
Additional levels of availability may be gained by deploying Cisco NSF with SSO at other points in the network where a single point of failure exists. Figure 2 illustrates an optional deployment strategy that applies Cisco NSF with SSO at the enterprise network access layer. In this example, each access point in the enterprise network represents another single point of failure in the network design. In the event of a switchover or a planned software upgrade, enterprise customer sessions would continue uninterrupted through the network.
Figure 2 Cisco NSF with SSO Network Deployment: Enterprise Networks
Further Information About SSO
For further information on SSO, see the"Stateful Switchover" chapter in the Cisco IOS XE High Availability Configuration Guide.
NSF Overview
Cisco NSF works with the SSO feature in Cisco IOS XE Software. SSO is a prerequisite of Cisco NSF. NSF works with SSO to minimize the amount of time a network is unavailable to its users following a switchover. The main objective of Cisco NSF is to continue forwarding IP packets following an RP switchover.
Usually, when a networking device restarts, all routing peers of that device detect that the device went down and then came back up. This transition results in what is called a routing flap, which could spread across multiple routing domains. Routing flaps caused by routing restarts create routing instabilities, which are detrimental to the overall network performance. Cisco NSF helps to suppress routing flaps in SSO-enabled devices, thus reducing network instability.
Cisco NSF allows for the forwarding of data packets to continue along known routes while the routing protocol information is being restored following a switchover. With Cisco NSF, peer networking devices do not experience routing flaps. Data traffic is forwarded through intelligent line cards or dual forwarding processors (FPs) while the standby RP assumes control from the failed active RP during a switchover. The ability of line cards and FPs to remain up through a switchover and to be kept current with the Forwarding Information Base (FIB) on the active RP is key to Cisco NSF operation.
Versioning Capability in Cisco IOS XE Software to Support ISSU
Before the introduction of the ISSU capability, the SSO mode of operation required each RP to be running like versions of Cisco IOS XE Software. The operating mode of the system in a redundant HA configuration is determined by exchanging version strings when the standby RP registers with the active RP.
The system entered SSO mode only if the versions running on both RPs were the same. If not, the redundancy mode was reduced to ensure compatibility. With ISSU capability, the implementation allows two different but compatible release levels of Cisco IOS XE images to interoperate in SSO mode and enables software upgrades while packet forwarding continues. Version checking done before ISSU capability was introduced is no longer sufficient to allow the system to determine the operating mode.
ISSU requires additional information to determine compatibility between software versions. Therefore, a compatibility matrix is defined that contains information about other images with respect to the one in question. This compatibility matrix represents the compatibility of two software versions, one running on the active and the other on the standby RP, and to allow the system to determine the highest operating mode it can achieve. Incompatible versions will not be able to progress to SSO operational mode.
The Cisco IOS XE infrastructure has been internally modified and redesigned to accommodate subsystem versioning with ISSU. Cisco IOS XE subsystems correspond to feature sets and software component groupings. Features or subsystems that maintain state information across RPs are HA-aware or SSO clients. A mechanism called ISSU Framework, or ISSU protocol, allows subsystems within Cisco IOS XE software to communicate RP to RP and to negotiate the message version for communication between RPs. Internally, all NSF- and SSO-compliant applications or subsystems that are HA-aware must follow this protocol to establish communication with their peer across different versions of software. (For further information on operating modes, see the "Stateful Switchover" chapter in the Cisco IOS XE High Availability Configuration Guide.)
Compatibility Matrix
You can perform the ISSU process when the Cisco IOS XE Software on both the active and the standby RP is capable of ISSU and the old and new images are compatible. The compatibility matrix information stores the compatibility among releases as follows:
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The compatibility matrix represents the compatibility relationship a Cisco IOS XE Software image has with all of the other Cisco IOS XE Software versions within the designated support window (for example, all of those software versions the image "knows" about) and is populated and released with every image. The matrix stores compatibility information between its own release and prior releases. It is always the newest release that contains the latest information about compatibility with existing releases in the field. The compatibility matrix is available within the Cisco IOS XE Software image and on Cisco.com so that users can determine in advance whether an upgrade can be done using the ISSU process.
Before attempting an ISSU, you should determine the compatibility level between the Cisco IOS XE Software versions on the active and the standby RPs. To display the compatibility matrix data between two software versions on a given system, enter the show issu comp-matrix negotiated command.
For information on the interoperability of different Cisco IOS XE software releases for the Cisco ASR 1000 Series Aggregation Services Routers, see the "Cisco IOS XE Software Package Compatibility for ISSU" section in the Cisco ASR 1000 Series Aggregation Services Routers Software Configuration Guide.
SNMP Support for ISSU
ISSU - SNMP for SSO provides a mechanism for synchronizing the Simple Network Management Protocol (SNMP) configurations and the MIBs that support SSO from the active RP to the standby RP, assuming that both RPs are running the same version of Cisco IOS XE Software. This assumption is not valid for ISSU.
ISSU - SNMP provides an SNMP client that can handle ISSU transformations for the MIBs. An SNMP client (SIC) handles ISSU for all MIBs and handles the transmit and receive functions required for ISSU. During SNMP, a MIB is completely synchronized from the active RP to the standby RP only if the versions of the MIB on both Cisco IOS XE releases are the same.
ISSU-Capable Protocols and Applications
The following protocols and applications support ISSU:
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How to Perform the Cisco IOS XE ISSU Process
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 IOS XE 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)" chapter in the Cisco ASR 1000 Series Aggregation Services Routers Software Configuration Guide.
Configuration Examples for Performing the Cisco IOS XE ISSU Process
For ISSU configuration examples for the Cisco ASR 1000 Series Router, see the "In Service Software Upgrade (ISSU)" chapter in the Cisco ASR 1000 Series Aggregation Services Routers Software Configuration Guide.
This section contains the following examples that verify the redundancy mode and the ISSU state before you begin the ISSU process:
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Verifying Redundancy Mode Before Beginning the ISSU Process: Example
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 statesmy state = 13 -ACTIVEpeer state = 8 -STANDBY HOTMode = DuplexUnit ID = 48Redundancy Mode (Operational) = ssoRedundancy Mode (Configured) = ssoRedundancy State = ssoMaintenance Mode = DisabledManual Swact = enabledCommunications = Upclient count = 67client_notification_TMR = 30000 millisecondsRF debug mask = 0x0Router# show platformChassis type: ASR1006Slot Type State Insert time (ago)--------- ------------------- --------------------- -----------------0 ASR1000-SIP10 ok 02:48:560/0 SPA-2X1GE-V2 ok 02:46:380/1 SPA-2XOC3-POS ok 02:46:38R0 ASR1000-RP1 ok, active 02:48:56R1 ASR1000-RP1 ok, standby 02:48:56F0 ASR1000-ESP10 ok, active 02:48:56F1 ASR1000-ESP10 ok, standby 02:48:56P0 ASR1006-PWR-AC ok 02:47:55P1 ASR1006-PWR-AC ok 02:47:55Slot CPLD Version Firmware Version--------- ------------------- ---------------------------------------0 07091401 12.2(33r)XN2R0 07062111 12.2(33r)XN2R1 07062111 12.2(33r)XN2F0 07051680 12.2(33r)XN2F1 07051680 12.2(33r)XN2Verifying the ISSU State: Example
The following example displays and verifies the ISSU state:
Router# show issu state detail--- Starting installation state synchronization ---Finished installation state synchronizationNo ISSU operation is in progressThe 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+found1114113 drwx 65536 Nov 25 2008 16:58:36 +00:00 tracelogs294913 drwx 4096 Jul 24 2008 15:14:39 +00:00 core12 -rw- 225308932 Nov 12 2008 15:50:37 +00:00 asr1000rp1-adventerprisek9.02.02.00.122-33.XNB-20080810_010002-mcp_dev_2.bin13 -rw- 209227980 Aug 20 2008 17:31:59 +00:00 asr1000special14 -rw- 222240972 Sep 8 2008 17:13:22 +00:00 rp_super.ppc.bin15 -rw- 209985740 Nov 25 2008 16:50:39 +00:00 asr1000rp1-adventerprisek9.02.01.02.122-33.XNA2.bin39313059840 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+found1507329 drwx 73728 Nov 25 2008 16:58:50 +00:00 tracelogs2424833 drwx 4096 Jul 24 2008 15:22:04 +00:00 core12 -rw- 225308932 Sep 8 2008 04:48:39 +00:00 asr1000rp1-adventerprisek9.02.02.00.122-33.XNB-20080810_010002-mcp_dev_2.bin13 -rw- 209227980 Aug 20 2008 17:41:21 +00:00 asr1000special14 -rw- 222240972 Sep 8 2008 18:04:26 +00:00 rp_super.ppc.bin15 -rw- 209985740 Nov 25 2008 16:55:11 +00:00 asr1000rp1-adventerprisek9.02.01.02.122-33.XNA2.bin39313059840 bytes total (38438928384 bytes free)Additional References
The following sections provide references related to the Cisco IOS XE ISSU feature.
Related Documents
Cisco nonstop forwarding
Stateful switchover
FHRP and HSRP group shutdown
`Configuring HSRP" chapter in the Cisco IOS XE IP Application Services Configuration Guide
ISSU on the Cisco ASR 1000 Series Routers
Cisco ASR 1000 Series Aggregation Services Routers Software Configuration Guide
VRRP
"Configuring VRRP" chapter in the Cisco IOS XE IP Application Services Configuration Guide
High availability commands
Standards
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
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 the Cisco IOS XE ISSU Process
Table 2 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 Cisco IOS XE 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
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