Many people were relieved to see Apple include support for Cisco VPN in the Snow Leopard version of Mac OS X; however, the implementation in the operation system is limited to TCP connections and does not support the UDP protocol. This has stopped several people from being able to connect using the built-in client.
If your VPN server is set up to accept connections over UDP only, you will not be able to connect using Apple's client. As such, for people connecting to servers that are set up to accept connections via UDP, the use of Cisco's third-party VPN client is still needed. Fortunately, theCisco VPN client works well in Snow Leopard, so those who need this alternate connectivity can still do it by obtaining the client from here: http://www.cisco.com/en/US/products/sw/secursw/ps2308/index.html
If you need UDP support in your Cisco VPN connections, we encourage you to request it from Apple on its OS X feedback page: http://www.apple.com/feedback/macosx.html. Hopefully, Apple will add or enable UDP support to the built-in Cisco client in a future update.
Topher has been an avid Mac user for the past 10-15 years, and has been a contributing author to MacFixIt for just over a year now. One of his diehard passions has been troubleshooting Mac problems and making the best use of Macs and Apple hardware both for family and friends, as well as in the workplace. He and the newly formed MacFixIt team are hoping to bring enhanced and more personable content to our readers, and keep the MacFixIt community going here at CNET. If you have questions or comments for Topher or the other MacFixIt editors, feel free to contact us at http://www.macfixit.com/contactResources