Check http://blogs.technet.com/rrasblog/archive/2005/12/22/416421.aspx for information to enable RAS logs on the earlier Windows Versions.
RAS Trace logs help in troubleshooting RAS connections related issues. On the earlier versions of Windows, "netsh ras set tracing * enabled" command enables the tracing. Though this command continues to work on Vista/Longhorn Server, a better place to enable tracing is from "netsh ras diagnostics".
Development LeadRouting and Remote Access Team,
Windows Enterprise Networking
[This posting is provided "AS IS" with no warranties, and confers no rights.]