If you want to be more precise in your estimations of user bandwidth requirements to support your regional site, you can calculate bandwidth requirements by using a formula that takes into account a greater number of variables.
This section describes a method for calculating network bandwidth requirements and use, as well as the distribution of operations per second per employee per region. By using these calculations, you can more accurately quantify the amount of bandwidth a regional site will require to access a centrally-hosted SharePoint Products and Technologies solution. In addition, you can determine the effect that a SharePoint Products and Technologies deployment will have on the WAN.
Methodology
Use the following steps to calculate bandwidth requirements:
- Gather profile data:
- Develop a regional profile to determine the size and activity level of a regional user community.
- Develop a usage profile to determine the number of operations performed by an average regional user within a given day.
- Develop a network profile for each class of operation specified in the usage profile.
- Compute the total number of operations performed by the regional user community within a given day.
- Compute the bandwidth requirements of the region.
This methodology assumes that the WAN topology uses a hub-and-spoke (centralized) model where the hub represents the data center that hosts the portal site and the spokes represent the network connections to the regions that want to use the portal site.
This method can be expanded and refined if necessary. In general, this method provides a reasonable approximation of required bandwidth.
Step 1 — Gather Profile Data
Regional Profile
The first step is to characterize the regional site by size and user activity level. A regional profile contains the following information:
- The total number of employees at the remote office
- The number of hours each employee works per day
- The percentage of users active per day
Usage Profile
The usage profile estimates the number SharePoint Products and Technologies user operations that a typical user at the regional site will perform in a typical day. Bandwidth use of user actions falls into two categories based on the amount of data transferred over the WAN:
- Common user operations Browsing through sites and viewing average-size pages
- Complex user operations Uploading or downloading a document
Network Profile
The Network Profile establishes the average network cost associated with each user operation defined in the user profile. Therefore, the network profile represents the network cost of using the SharePoint Products and Technologies solution. The network profile takes into account the amount of data that is traveling over the WAN based on user-generated operations:
- Network cost of a common user operation The network cost of a common operation is the size of the Web page that is browsed or viewed. You can determine the network cost of common user operations by averaging a sampling of popular portal site pages. A typical sampling includes the following pages:
- The home page for the main portal site
- The home page for a top-level Windows SharePoint Services site
- A typical private My Site home page
- A fully-populated Search Results page for the main portal site
- Network cost of a complex user operation Because a complex operation deals with uploading or downloading a document, the network cost of this operation is the average size of a typical file. You can apply a fixed value, such as 250 KB.
Step 2 — Calculate the Normalized User Operations Per Second
Use the data gathered in the previous profiles to calculate the normalized user operations (NOPs) per second. This number represents the total number of normalized user operations performed by a regional user community in a typical day. Therefore, the result represents the average continuous impact that a typical regional user community has on the SharePoint Products and Technologies solution.
Calculate the normalized user operations per second by using the following formula:
The following is a symbolic representation of the formula:
The following table explains the variables used in the formula.
| ID |
Term |
Definition |
| A |
Number of potential users |
The total number of users potentially using the SharePoint Products and Technologies solution. |
| B |
Percent of users active per day |
The percentage of the total number of users who are likely to use the solution during a typical day. This figure is typically approximately 25 percent, but can vary from 10 to 75 percent. |
| c |
Number of common user operations per active user per day |
The number of common user operations that a typical user generates on the portal site during a typical day, such as viewing a Web page. Typically, this number is approximately 50, but it can vary depending on the organization. |
| d |
Number of complex user operations per active user per day |
The number of complex user operations that a typical user generates on the portal site during a typical day, such as uploading or downloading a document. Typically, this number is approximately 10, but it can vary depending on the organization. |
| e |
Network cost (KB) – common user operation |
The total number of kilobytes transferred across the network when a common user operation is performed. Typically, this number is approximately 125, but can vary between 100 and 150 depending on page design. |
| f |
Network cost (KB) – complex user operation |
The total number of kilobytes transferred across the network when a complex user operation is performed. Typically this number is fixed at 250. |
| g |
Complex user operation Weight |
The weight of a complex user operation, in relation to a common user operation. This is determined by the following formula:
[ f / e ] |
| H |
Number of Normalized User Operations per active user per day |
The total number of Normalized User Operations that a typical user generates on the portal site during a typical day, determined by the following formula:
[ (1 * c) + (g * d)] |
| J |
Number of hours per day |
The number of hours during which most activity occurs. This number typically ranges between 6 and 14 hours. |
| K |
Peak factor |
An approximate number that estimates the extent to which the portal site usage exceeds the average usage. This number typically ranges from 5 to 10. |
|
360000 |
A constant value determined by the following formula:
[ 100 (for percent conversion) × 60 (# of minutes in an hour) × 60 (# of seconds in a minute) ] |
Notes
- Normalization occurs by weighting a complex user operation such that it can be expressed in terms of a common user operation.
- This weighting is the ratio of an averaged-sized document associated with a complex user operation to that of an average-sized Web page associated with a common user operation.
- Because normalization occurs with respect to a common user operation, the common user operation is, in effect, the baseline user operation.
Step 3 — Calculate the Total Bandwidth Requirement
Use the result of the previous calculation to determine the total bandwidth required to support users at the regional site.
The formula presented in this section (Total Bandwidth Utilization formula) determines the percentage of available bandwidth that is required to support the usage profile associated with your regional site. This result represents the average continuous impact that the group of regional users will likely have on the WAN connection between the regional and central site.
Use the following formula:
The following is a symbolic representation of the formula:
The following table explains the variables used:
| ID |
Term |
Definition |
| A |
Network cost (KB) of the baseline user operation |
The total number of kilobytes transferred across the network when a common user operation is performed. |
| B |
Number of Normalized User Operations per second |
The total number of Normalized User Operations per second performed on the portal site by the group of users. |
| C |
Total bandwidth available |
The total bandwidth (Mbps) available on the network connection or connections that link the group of users to the portal site. Consider only those connections that link the user directly to the portal site. |
Email this link
Printer-Friendly Version
Share
