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I just wanted to know how do we calculate the actual bandwidth requirement for a small office (30 users) before ordering the actual Internet line from isp we have 4 Dell 2950 servers , 4 Cisco 3560 switches locally. Remote vpn connectivity, to USA. Current location -IND.

The original question was moved here after it was closed as "primarily opinion-based"

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I would like to know how do we calculate the actual bandwidth requirement for a small office (30 users)

If all the information I had was in your question, I would say between 5Mbps to 10Mbps (symmetric upload/download speeds); depending on pricing and your own personal opinions about my questions below.

The question was moved here after closure as "primarily opinion-based"

Asking this question on Network Engineering is an exercise in speculation which is not something we encourage here. So, why are questions about your office bandwidth requirements speculative?

  • How could we possibly know your local ISP selection or what packages you could get from them?
  • How could we possibly know the frequency that your users will need to access corporate applications vs locally hosted applications?
  • How could we possibly know each individual application bandwidth requirements?
  • How could we possibly know the rate of office growth in the next 2 years (just picking a number I might try to plan for)?
  • How could we possibly know your corporate expectations for performance in this office (do the executives think of this office is a throw-away, or are they very interested in the location)?
  • How could we possibly know how bored your users will get (i.e. youtube / facebook)?
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  • I really want this to be on-topic, but calculating someone's bandwidth requirements is so subjective that it's at odds with the SE policy. – Ryan Foley Dec 11 '14 at 11:02
  • We can always help people in chat, if we can get them to ask there – This Dec 11 '14 at 11:08
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The answer that Mike Pennington gave is the best 'real world' answer, but Cisco documentation lists ~1.5mbps symmetric. I think they assume you to have a private lease line and use traffic engineering to deprioritize or drop non-business critical data. In this day and age, you can't really get by without people using streaming internet services - so know that his answer is the more accurate one, in that regard.

I think a good approach for psuedo-realistic accuracy, is to enable NetFlow/Flexible NetFlow on your current equipment (Router or Switch, if supported) and export it to a NetFlow collector. Further, use of IP SLA could also help you in capacity planning, but will not be as effective or fruitful as NetFlow.

I can't tell by your question if you're setting up a new office or migrating an existing office to a new connection. However, assuming this is a new office and you can't get a baseline. You could use NetFlow on your current corporate network and divide out the user population into percentage of segment use (or percentage of VLAN use) and you'll end up with a close enough estimate to baseline. Look at your new office layout and access requirements. This will give you a minimum value.

By collecting NetFlow data, you can see when your peaks are occurring, what kind of traffic it is, and watch overall conversations inside and outside the network. Some additional things to keep in mind, is expansion. Don't order circuits that are needed today, when you're getting X new hires over the next year, or couple years even. It may be more expensive up front, but this is why you need to think about needs over time.

Lastly, don't overlook the usefulness of QoS. You CAN draw blood from a stone, especially if you have a mix of critical and non-critical data. Instead of making the entire pipe bigger, you can give first access to those critical services, and either drop or slow down the non-crit traffic.

As a final aside, if this is a big issue - look into a traffic analyzer if netflow isn't supported on your equipment. Setup a SPAN port, as appropriate, and let it watch your network activity. Make conclusions from there.

Here's what Cisco is saying about capacity planning, but don't expect to draw anything other than conceptual knowledge:

http://www.cisco.com/web/about/ciscoitatwork/network_systems/network_capacity_planning_web.html

http://www.cisco.com/web/about/ciscoitatwork/downloads/ciscoitatwork/pdf/Cisco_IT_Case_Study_Capacity_Planning_Presentation.pdf

http://www.cisco.com/c/en/us/products/collateral/cloud-systems-management/network-planning-solution/prod_white_paper0900aecd804b9201.html

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  • Without knowing what each of the 30 users are normally going to be doing, all we can do is guess. And that's all Cisco's documentation can do as well. – Ricky Dec 16 '14 at 9:24

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