Chapter 13: LAN Maintenance

1. Chapter 13: LAN Maintenance

2. Documentation • Document your LAN so that you have a record of equipment location and configuration. Documentation should include network maps, configuration information, and baseline performance data. • You should be able to easily locate which switch port a particular network point corresponds to. Remember to remove the patch cable from the switch if a network point is no longer in use. • You should be aware of which hardware device drivers are required for computers. Download and store device drivers somewhere safe, so that they are easily accessible when needed.

3. Baselines • Monitor server performance during normal working hours. • What is the average processor usage? • What is the average disk read/write activity? • Monitor network performance during normal hours. • What percentage of the network bandwidth is being used? • What percentage of traffic on the network is broadcast frames as opposed to unicast frames? • Keep these statistics and refer back to them regularly. If necessary, you can use historical trends (for example: increasing use of network bandwidth over time) as a convincing argument to management for new equipment purchases.

4. Data Retention Policies • When designing a data retention policy, you should address the following questions. • How long should your company store e-mail? • In legal cases, past e-mail can be subpoenaed. Many organizations now have a policy where by e-mail is deleted after a certain amount of time from the mail server. • Should your organization keep archival backups? • How long should files that are no longer accessed be kept before they are deleted from your file server’s HDD?

5. Patch Management • Vendors regularly produce updates, hotfixes, and service packs for operating systems. • These updates should be tested in a limited environment before they are deployed to all computers on the LAN. It might be that a particular update has undocumented side effects that render a system unusable. • Monitor vendor security bulletins for information about issues that might influence the computers on your LAN. • Balance the need to update regularly with the impact on users of constantly updating computers with new fixes.

6. Windows Update Services Microsoft’s freely available Windows Update Services allow a single server on the LAN to distribute patches to all computers on the network. This reduces network traffic as a patch needs to be downloaded from the Internet only once, rather than to each specific computer. patch deployed many times across LAN patch downloaded once From Internet

7. Create Images • Disk imaging software allows you to create an exact copy of an operating system and all of its installed applications. • Rather than attempting to troubleshoot a computer that has a mysterious fault, you can simply re-image it back to default configuration. • When using imaged computers, ensure that users store all their data on file servers. • If using Windows operating systems, remember that you will need to alter the unique SID using a utility like newsid before you can join the computer to the domain. • Windows XP introduces restore points, which allows you to roll back an operating system to a previous point in time.

8. SNMP • Simple Network Management Protocol can be used to monitor and manage network components, from routers to servers. • An SNMP agent resides on a host and gathers information. • An SNMP management application polls SNMP agents and collates the information for analysis and alerts. • SNMP management applications can be configured to send an e-mail alert or even to SMS a mobile phone in the event of a network failure.

9. Summary • You should keep up-to-date documentation of your organization’s network map, baseline performance, and hardware configuration. • A baseline should include both server and network performance. • You should keep up to date on hotfixes and patches. Test them on a small group of computers before deploying them to all hosts on the LAN. • Centralized patch management allows you to deploy patches centrally, rather than manually installing them on each computer. • Disk images allow you to quickly restore a corrupted operating system.

10. Discussion Questions • What statistics should you monitor when generating a baseline? • What advantages are there to using centralized patch management such as Windows Update Services? • What advantages are there to using disk imaging? • What is the difference between an SNMP agent and an SNMP management application?