Maintenance is no doubt an important component to network stability and that’s why we see it covered on the troubleshooting exam. This is perfect multiple-choice style content as it is difficult to test your understanding of maintenance concepts and methodologies on a simulation-focused exam like TSHOOT. Keep that in mind as you walk through the following topics.

Good troubleshooting reduces the time an outage lasts, good maintenance minimizes outages themselves.

Maintenance Methodologies

Several well known maintenance models have been defined by a number of organizations. Many organizations use parts of several instead of adopting one method completely, but it is important as a network engineer to understand what models exist and how they translate into improving your organization. A documented maintenance strategy is worth its weight in gold.

IT Infrastructure Library (ITIL)

ITIL focuses on creating a technology service framework within an organization and aligning it closely with the organization’s requirements and processes. Note that ITIL is a large and comprehensive approach that was developed specifically for IT professionals.

FCAPS

FCAPS is an IT maintenance model created by ISO that categorizes network management into five parts. FCAPS is an acronym using the first letters of the five categories it includes.

Fault management

■ Preventive maintenance
■ Minimizing network downtime

Configuration management

■ Both hardware and software installation and configuration
■ Change control
■ Inventory management

Accounting management

■ Capacity planning
■ Cost efficiency

Performance management

■ Maximize performance on existing network investments

Security management

■ Confidentiality, integrity, availability (CIA)
■ Authentication, authorization, accounting (AAA)
■ Encryption
■ Intrusion detection/prevention

Cisco Lifecycle Services

Cisco has come up with their own maintenance model, sometimes also referred to as PPDIOO, or Prepare, Plan, Design, Implement, Operate, and Optimize. This model is specifically focused on deploying and operating Cisco’s product families.

Telecommunications Management Network (TMN)

TMN was developed by ITU-T and is a tailored version of FCAPS specific to the telecommunications industry.

Once the model has been selected, its parts should inform an IT organization’s processes and standard procedures. After all, a model is meaningless unless it affects how a business operates.

After the maintenance model components have defined an organizational processes (ex. automated config backups, manual security audits, etc.), tools should be selected to carry out those processes. FTP could be used for configuration backups for example.

Network Maintenance Core Tasks

Whatever model an IT organization chooses, there a some functions that should be included every time. These include:

■ Managing adds, moves, and changes
■ Installing and configuring new network devices
■ Replacing failed hardware
■ Software backup
■ Configuration backup
■ Troubleshooting failure scenarios
■ Software upgrades
■ Network performance monitoring
■ Capacity planning
■ Creating/updating network documentation

Documentation

Up-to-date, clear, and complete infrastructure documentation is crucial to reduce recovery times and maintain a robust networked environment. Different levels of detail are appropriate for different audiences, but some common details that should be documented include:

■ Production configurations
■ Inventory (including serial numbers, support info, etc.)
■ Circuit information
■ Network drawings
■ IP address assignments

Another important component to network documentation is a performance baseline, or snapshot. It captures the expected performance of your network systems like link bandwidth, WAN jitter and delay, and port status. This is a tremendous help during troubleshooting efforts because without knowing what normal levels are, detecting abnormal traffic behavior becomes very subjective.

IOS Tools

Configuration

Configurations should be backed up periodically or after changes are made. One of the simplest methods is to save the configuration as a text file on a remote TFTP or FTP server. TFTP and FTP servers are available on all modern operating systems and free, open source offerings are widely available.

Adding the date to the saved configuration can make rolling back changes easier in the future. Here’s an example of a router saving it’s configuration to a local TFTP server:

RouterA# copy run tftp
Address of name of remote host []? 10.10.1.35
Destination filename [routera-config]?routera

Syslog

Syslog is a tool that collects alerts from network devices and stores them on a common log. Obviously, this can be very handy when you need to troubleshoot an issue across many devices.

Know that every syslog message contains two parts, a severity level and a facility. The severity level goes from 0 to 7 with 0 being the most severe to 7 being simply informational.
Syslog Priority (highest to lowest):

0. Emergency (highest)
1. Alert
2. Critical
3. Error
4. Warning
5. Notice
6. Informational
7. Debug (lowest)

NTP

Alerting is important, but if the timestamps that are included are not correct, then the alerts are unreliable (and next to useless). NTP stands for Network Time Protocol and is used to keep accurate and consistent time on all network devices. NTP works by using pulling the current time from a time server, each of which are assigned by stratum. Stratum 1 clocks are synchronized directly with an atomic clock, stratum 2 clocks get their time from stratum 1 clocks, etc.

Configuring NTP is easy – just point the device to the proper time server:

Switch(config)# ntp server ip_address_of_ntp_server

To verify:

Switch# show ntp status

One last note for NTP, it is important to consider the time zone that each device is set to. Make sure you have it consistent (ex. local time zones, GMT, HQ time zones, etc)

CCNP TSHOOT 642-832 :: Network Maintenance