| 5.5 |  | Managing the Router |
| 5.5.3 |  | Updating the router |

| Periodically, the router will require updates to either the operating system or the configuration file , . Before updating, the administrator should complete the following checks:

- Determine the memory required for the update, and install additional memory if necessary.
- Set up and test file transfer capability between the administrator’s host and the router.
- Schedule the required downtime for the router to perform the update, usually after regular business hours.

After obtaining an update from the router vendor and verifying its integrity, the administrator should perform the following procedures:

- Shut down or disconnect the interfaces on the router
- Back up the current operating system and the current configuration file to the administrator’s computer
- Load the update for either the operating system or for the configuration file
- Perform tests to confirm that the update works properly
- If the tests are successful, then restore or reconnect the interfaces on the router.
- If the tests are not successful, then discontinue the update.

Motivations for Updating Router Software
Installing an IOS update entails inconvenience and the risk of disruption of service. The benefits of upgrading should be weighed against the risks before starting. The following list describes some good reasons for installing an update:

- To fix known vulnerabilities - When there are security vulnerabilities exist, one solution may be to upgrade to a later edition of the IOS software.
- To support new features - Cisco has added new operational and security features to each new IOS release. If one or more of these features are needed to support the network, or to enforce the local security policy, then it makes sense to upgrade.
- To improve performance - The router might need an upgrade to support new hardware or hardware features. If the performance benefit is greater than the cost of upgrading, then do the upgrade.

Software updates may entail substantial costs for the following reasons:

- The router must be out of service for at least a short time during the installation process. Depending on router model and other factors, the minimum downtime will range from about a minute to several minutes.
- Some features may not work in a newer release because they might be broken or simply unsupported. It is very important to read the release notes for a new release carefully before installing it to ensure that the new software fully supports existing router functions.
- A new release may degrade performance, either by implementing new features or by reducing available free memory. If the performance of the router is critical, measure the performance before upgrading, and again afterwards, and be prepared to back out if the performance has suffered.

Deciding which update to pick is a complex topic. Factors that must be taken into account include

- Feature availability
- Release status
- Cost
- Router cost
- Router memory size
- Bug history

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