Specifications

CHAPTER 5

Implementing High Availability

n Communication and documentation: There should be good communication between teams responsible for the

network, security, servers, and applications. There should also be communication with users. Good documentation,

readily available, is critical to understanding how the network is designed and how it should behave during a failure.

n Sufficient time to accomplish a task: Not having enough time to accomplish a network-related task leads to impor-

tant components, such as testing and documentation, being left out. The design target should be a better than just

“adequate” network.

n Align staff with the services they support: This helps ensure clear lines of responsibility for the different segments

of the network. Be sure to include the people responsible for a segment in the planning for its high availability.

Processes

Companies that build repeatable processes and design templates have more cohesive networks and save time in trou-

bleshooting problems. Process documentation should include configuration change procedures, failover and lab testing

procedures, and network implementation procedures. These should be regularly reviewed and improved as part of the

PPDIOO process.

A lab that reflects the current production network enables thorough testing and validation of such changes as new config-

urations and IOS versions and ensures that the staff thoroughly understands network failover processes.

Having a meaningful change control process includes the complete testing of all changes and how they affect failover

within the entire network before they are implemented. Changes must be well planned with a roll-back strategy in place.

A risk analysis can also help determine if the change is worthwhile.

Network management processes are often overlooked. These should include:

n Capacity audits

n IOS version management

n Corporate best-practice design compliance

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CCNP SWITCH 642-813 Quick Reference by Denise Donohue