Questions to ask to determine WAN bandwidth requirements

• 
  Paul Kirvan
• Published: 20 Mar 2009

How can you build a network without knowing the bandwidth needed? Business and financial issues, competition and...

existing network topology issues will affect your decisions. Should you look at your bandwidth requirements in terms of the whole network or parts of it? Perhaps you can segment and subdivide your network so that issues in any one part won't limit your ability to address unique requirements of other parts.

In order to develop a network that fulfills your requirements today and can accommodate future demands, it makes sense to develop a migration path on a network-by-network basis, then revisit and reassess each element in that path over time. With market, business, and technology dynamics changing quickly, you must keep a watchful eye on your network so that it can dynamically support opportunities as they occur.

Gathering business information
When addressing bandwidth management, business issues cannot be overlooked. This means that as a network manager you must identify several key factors:

1. Current and potential users of network resources
2. Primary activities, such as email, file transfers and the applications to support them
3. Types of devices to be used, such as PCs, laptops and printers
4. Expectations for network performance
5. Other applications currently being used, such as voice, and video
6. Applications planned for future use
7. Amount and frequency of data users plan to download or upload
8. Security issues like data encryption.

Unlike servers and routers, which can be configured and reconfigured at any time, bandwidth as a network design element should be done correctly (e.g., optimized) the first time, when the network is first launched. After that, regular reviews of network performance are necessary to ensure that sufficient bandwidth is available.

Questions to identify bandwidth requirements
We can convert the above criteria into specific interview questions to ask when identifying bandwidth requirements. Schedule appointments with your key technical users, such as applications programming, database management, information security and data center, and key business departments such as human resources, legal, and administration.

For each current and potential department using network resources, ask:

What are their primary functions?

Best practices for WAN design and capacity planning WAN design: What to consider WAN capacity planning: Building a methodology Determining WAN bandwidth requirements