What causes my overseas VPN connection to slow during the day?

What causes my overseas VPN connection to slow during the day?

I am using a Nortel Connectivity VPN client and connecting to a remote site in France. When I am connecting in the morning the speed is ok, however, during the day the speed of the connection gradually gets slower and slower until a screen refresh can potentially take up to 1-2 minutes. Do you have any idea what could be causing this? The site is using broadband at about 400 Kbps upload and just under 3 Mbps download. We have a Windows 2003 SBS network with a domain, and a Vigor 2600 router/modem as a gateway. The version of the client is 4.01.

    Requires Free Membership to View

    By submitting your registration information to SearchNetworking.com you agree to receive email communications from TechTarget and TechTarget partners. We encourage you to read our Privacy Policy which contains important disclosures about how we collect and use your registration and other information. If you reside outside of the United States, by submitting this registration information you consent to having your personal data transferred to and processed in the United States. Your use of SearchNetworking.com is governed by our Terms of Use. You may contact us at webmaster@TechTarget.com.

Since your performance appears to be related to the time of day, it is likely due to congestion points in the network. One possibility is that you may be suffering from congestion on the link over the Atlantic. Depending on your Internet provider's peers, the trans-Atlantic connections can be undersized for peak usage, particularly during US business hours. This can result in high latency and packet loss, and a corresponding drop in throughput. You could confirm this by testing your performance outside of the VPN during the slow times, from a server located in France.

Another issue could be the number of users on the host site concentrator. Congestion on this server could also result in slower user performance. You can confirm the concentrator load by examining its logs for the number of concurrent users during the slow performance period. Your VPN provider should be able to provide guidance on whether this number is within the specifications for the concentrator capacity.

This was first published in April 2007