The University of Texas at Austin

Virtual Private Network

Technical Information for VPN: VPN Split Tunneling

Data traffic consumes bandwidth, a measure of how much information can be sent over a network during a specific unit of time. Bandwidth is usually measured in megabytes per second, or Mbps. If too much data flows through a network, the network can experience lag, or delays in response times. To alleviate lag and conserve bandwidth, the campus VPN supports the concept of split tunneling for connected users. Simply defined, this means that some of your data travels through the VPN tunnel, while the rest travels over your normal, unencrypted connection.

Graphic illustration of a split tunnel VPN

Whenever you activate your VPN connection from a remote location, the data's destination is categorized before any data is sent over the Internet. Your VPN client software checks all outbound traffic to see whether or not that data is headed for campus. Based on that check, the VPN client addresses your packet in one of two ways:

  • Campus traffic - All data that is destined for the University of Texas campus is addressed so that it is delivered to the VPN server at the University of Texas. This includes University of Texas Web pages, applications, and department servers, and any other machine connected to the campus network.The data packets are encrypted before being forwarded to your regular network adapter. Each encrypted packet includes the final destination address for that packet.

  • Non-campus traffic - Any data that is not related to a UT Austin machine and service is not addressed for delivery to campus. Therefore, it travels normally from your machine to your ISP and then makes its way to its eventual destination. This keeps your non-campus Internet activity private and conserves bandwidth on the campus network.

Two main benefits arise from the "split-tunneling" approach.

  • It conserves bandwidth on the campus network. When fewer packets travel to campus, more bandwidth is available. This reduces delays on the network (lag) for campus users. Additionally, your non-campus traffic is not counted against any campus bandwidth limits.

  • It helps protect privacy. The university's privacy policy strives to keep your information confidential, and this extends to your VPN connection. If you visit a Web page or server from home that is not located on the UT Austin campus, that information never reaches the VPN server. Your home network traffic will not be limited or monitored in any way by the VPN.

Last updated November 16, 2012 @ 4:27 pm

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