Client network traffic is area that often generates many questions. This area is frequently the subject of discussion when site consolidation is being discussed which also raises the issues of network cost and sizing.
While there is some information available on how to estimate this client network traffic, this is mostly relevant to Exchange 2007 and Outlook 2007. I am not aware of any changes in Exchange 2010 and Outlook 2010 that will change the client network requirements, so the information below is based on this.
The first bit of information you need are user profiles, use the Microsoft Exchange Server Profile Analyzer tool to collect this information if you don’t already have it. You can download the Microsoft Exchange Server Profile Analyzer tool from the links provided at the bottom of this page.
| Profile | Light | Medium | Heavy | Very Heavy |
| Sent/Day | 5 | 10 | 20 | 30 |
| Received/Day | 20 | 40 | 80 | 120 |
| Ave Msg Size | 75kb | 75kb | 75kb | 75kb |
| Msgs Read/Day | 20 | 40 | 80 | 120 |
| Msgs Del’d/Day | 10 | 20 | 40 | 60 |
| OWA logon/Day | 2 | 2 | 2 | 2 |
Next we determine how much traffic is generated by each user profile per day. In the table below, all values are in Kilobytes/User/Day. The table separates sending from all other actions which are labelled as aggregate.
| Profile | Light | Medium | Heavy | Very Heavy | |
| Sending | 285 | 570 | 1,140 | 1,710 | |
| Outlook - Online | Aggregate | 3,765 | 7,545 | 15,075 | 22,605 |
| Total | 4,050 | 8,115 | 16,215 | 24,315 | |
| Sending | 390 | 780 | 1,560 | 2,340 | |
| Outlook - Cached Mode | Aggregate | 1,560 | 3,120 | 6,240 | 9,360 |
| Total | 1,950 | 3,900 | 7,800 | 11,700 | |
| Sending | 465 | 930 | 1,845 | 2,775 | |
| Outlook Anywhere | Aggregate | 1,845 | 3,705 | 7,410 | 11,100 |
| Total | 2,310 | 4,635 | 9,255 | 13,875 | |
| Sending | 1,200 | 2,400 | 4,800 | 7,200 | |
| Outlook Web App | Aggregate | 8,085 | 15,930 | 31,605 | 47,295 |
| Total | 9,285 | 18,330 | 36,405 | 54,495 |
Now that we have these values, how do we use them? The last piece of the puzzle is the formula. The following formula can be used to estimate the network traffic (in KB/Sec) required by your Exchange 2010 clients.
Using this formula and the data in the above tables, if we wanted to calculate the network requirements for 2,500 heavy users who use Outlook in Cached Mode it would look something like this:
Network Traffic (KB/Sec) = 677 KB/Sec. To convert this to Mbps:
Network Traffic (Mbps) = 5.4 Mbps.
This formula assumes all these users are in the same time zone, so they do the majority of the work during an 8 hour day.
This information is based on the original post from MS Exchange Team blog.
Download Microsoft Exchange Server Profile Analyzer (32 bit) here
Download Microsoft Exchange Server Profile Analyzer (64 bit) here