It is easier to recover from any network failure if you are prepared. Possibly the most important requirement in any network is to have current and accurate information about that network available to the network support personnel at all times. Only with complete information can intelligent decisions be made about network change, and only with complete information can troubleshooting be done as quickly and as easily as possible. Thus to minimize the downtime of all outages, current and accurate network is a necessity.
To determine whether you are prepared for a network failure, answer the following questions:
- Do you have an accurate physical and logical map of your internetwork?
Does your organization or department have an up-to-date internetwork map that outlines the physical location of all the devices on the network and how they are connected, as well as a logical map of network addresses, network numbers, subnetworks, and so forth?
- Do you have a list of all network protocols implemented in your network?
For each of the protocols implemented, do you have a list of the network numbers, subnetworks, zones, areas, and so on that are associated with them?
- Do you know which protocols are being routed?
For each routed protocol, do you have correct, up-to-date router configuration?
- Do you know which protocols are being bridged?
Are any filters configured in any bridges, and do you have a copy of these configurations?
- Do you know all the points of contact to external networks, including any connections to the Internet?
For each external network connection, do you know what routing protocol is being used?
- Do you have an established baseline for your network?
Has your organization documented normal network behavior and performance at different times of the day so that you can compare the current problems with a baseline?
Summarized from Cisco: https://www.cisco.com/en/US/docs/internetworking/troubleshooting/guide/tr1901.html
Jason Howe, PEI