Network maintenance is an integral component of a network management methodology. While in general network maintenance is assumed to be primarily concerned with repairs and upgrades, it should be noted that a comprehensive network maintenance solution also includes corrective and preventive measures, which allow for network optimization as well as the upkeep of network documentation, amongst other tasks, which are listed later in this chapter.
Network maintenance activities can be performed in a structured (scheduled) manner or on an as-needed (ad-hoc) basis. A structured or scheduled approach is based on predefined plan and is the recommended method for performing any network maintenance tasks. An example of structured maintenance might be a scheduled change window to upgrade the software versions on internetwork devices, such as routers and switches.
As-needed or ad-hoc maintenance activities are those that are performed when any issues arise. These maintenance activities, also referred to as interrupt-driven tasks, are tasks that are unplanned and typically cannot be predicted. An example of such a task would be replacing a failed Supervisor module or line card in a Cisco Catalyst 6500 series switch. Such maintenance activities are part of the day-to-day management of the network and cannot be completely eliminated; however, a structured maintenance approach can be used to mitigate their occurrences and their overall impact on the network as well as the organization in general.
A structured maintenance approach leverages proactive monitoring to detect and remedy any potential problems within the network itself or with internetwork devices. A proactive monitoring solution not only provides the organization with the ability to identify and remedy problems before they actually impact the production environment, but it also allows for capacity planning, which includes network upgrades, expansions, or enhancements. This allows network maintenance activities to be planned, scheduled and implemented in a controlled manner greatly increasing the overall probability of the success of those activities.
Without a structured maintenance approach in place, the majority of network maintenance tasks are performed in a reactive manner, increasing the number of resources required to maintain and support the network on a day-to-day basis, and also increasing the likelihood of significant and possible costly business impact, e.g. a network outage, at any given time.