Specifications

CHAPTER 5

Implementing High Availability

Chapter 5

Implementing High Availability

A highly available network is the goal of every network engineer. Having a highly available network makes the job easier

because it helps to prevent network outages and minimize downtime.

Components of High Availability

There are five components to high availability: redundancy, technology, people, processes, and tools. The first two can be

obtained through network design; the last three are more difficult to implement and control.

Redundancy

Redundancy attempts to eliminate single points of failure by providing duplicate devices and links. This costs more, so

the added cost must be balanced against the added benefit. Add redundancy where it will have the most impact on avail-

ability, in the core of your network, data center, or e-commerce module. Critical WAN or ISP connections are another

possible location.

A redundant network has path diversity with multiple links between multiple devices. It can have geographic diversity,

with data centers in multiple sites. Networks frequently have dual core and distribution switches, with dual uplinks to

each. Dual WAN providers, with dual WAN edge routers, are commonly used. Companies can design their networks with

connections to dual Telco central offices and power substations to achieve additional redundancy.

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CCNP SWITCH 642-813 Quick Reference by Denise Donohue

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