Wednesday, July 23, 2008

How To Determine How Much Bandwidth Your Client Needs For Their Business Network Architecture

When determining the amount of bandwidth a client needs, you first have to understand why the client needs internet/WAN connectivity. Initially you want work with the client to develop an idea of what the client wants to get from the internal network, in other words develop a list of business drivers.

Does the company require*:

?Use of VOIP
?Are they using Voip now
?Will the use it in the future
?How many trunks do they currently support and how much bandwidth is currently being used at the core by those trunks
?Use of IP Telephony (voice to the desktop)
?If they are using IP telephony, are they using only SIP or are they using other protocols and other applications of the feature set on the phones and what are the manufacturers recommended guidelines on bandwidth consumption
?If they are not using IP telephony, do they know what protocols and applications of the feature set on the phones they will use, and what are the manufacturers recommended guidelines on bandwidth consumption
?What internal applications do they use currently
?What are the bandwidth requirements of those applications currently
?What are the manufacturer or developer's guidelines on how much bandwidth to use
?Does the client plan to add additional applications they know are heavy on bandwidth usage?
?Does the client use any security scanning that may take up resources?
?When do the scans occur and are those during peak time
?Do they plan to add security scanning, and if so where (the core or edge or across aggregation points)?
?Does the client currently use QOS, and if so have they manually queued traffic or are they using difserv?

*These are a good sample of questions, but in short, you are conducting a workshop to identify the business and technical drivers of the organization

You will also want to examine the current network design, identify current bandwidth usage across the network, identify bottlenecks, and where T circuits are being employed, where they are using MPLS or metro-e circuits, where they are using dark fiber, if any.

Ultimately you want to understand where their current problems lay from layer 1 and 2 perspectives based on the current design and then you will need to break the network down logically at layer 3 and 4 examining what protocols are being used and how they are being broadcasted across broadcast domains which can create sluggish communications. Is the client using VOIP and not using QOS, is the client using a lot of DHCP relay, are there multicasts being broadcast that are creating superfluous traffic, etc...

Once you have a clear picture of the current network configuration and you have base lined the network, and have identified their current issues via a gap analysis then you can move on to identifying "how much bandwidth they need" internally.

From an external perspective you need to simply perform a firewall analysis of inbound and outbound traffic and match that against the CIR of your ISP pipe(s). You may also want to extrapolate any new data gleaned from your research into the forecasted use of applications for additional bandwidth usage in the future.

So to summarize you will need to use the following methodology:

1. Identify the business requirements and drivers
2. Understand the technical requirements
3. Identify how data is being transported currently
4. Conduct an OSI based network analysis
5. Develop a Gap analysis with suggested solutions
6. Develop a high level plan and provide the customer with an estimated band width requirement based on evidentiary matter obtained in steps 1 - 5.

Michael is the owner of FreedomFire Communications....including DS3-Bandwidth.com and Business-VoIP-Solution.com. Michael also authors Broadband Nation where you're always welcome to drop in and catch up on the latest BroadBand news, tips, insights, and ramblings for the masses.

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