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Wireless for redundancy

Implementing a wireless network is usually done for the sake of mobility, but why not consider it for redundancy?

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Effort spent to make the network redundant is almost exclusively devoted to servers and the backbone. Primarily, this is because when those two components fail, a large number of individuals are inconvenienced. Another reason is that there's never been a really good solution for making an individual laptop or desktop redundant, no matter how important the user is. These devices often have a single NIC and the cable can only go to one place. If that switch dies, there's no easy or automated way to move that physical cable into another switch. Dual NICs are cost prohibitive in many instances, and simply not an option in most of the laptop hardware.

However, almost everyone overlooks redundancy to the desktop as a benefit of typical wireless deployments. That is, most administrators realize that if a WAP fails, it is fairly simple to engineer the network so that other nearby WAPs can assume the load of the failed WAP, perhaps resulting in a degradation of service, but not an outage. However, no engineers I'm aware of have convinced their managers to deploy wireless specifically because of this inherent redundancy. As you know, the justification for wireless is always mobility and occasionally reduced cost by eliminating cable plants in new offices.

The point is, if you have a set of VIPs who need their network connectivity to be on, you can eliminate a point of failure by using wireless technology instead of traditional wired Ethernet.

While WAPs are already reasonably priced compared to wired Ethernet ports, expect the next version of WAPs to be designed and priced for dense coverage. That is, vendors will be selling WAPs that are cheaper, but that interact better (often dynamically adjusting their radios based on the neighbors they detect) and are intended to be used in groups.

Tom Lancaster, CCIE# 8829 CNX# 1105, is a consultant with 15 years experience in the networking industry, and co-author of several books on networking, most recently, CCSPTM: Secure PIX and Secure VPN Study Guide published by Sybex.

This was last published in November 2004

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