Hello,
Is there any PROM update available for Netra T1 AC200 which include the wanboot feature ... ?
No, this system went EOL before the feature was introduced.
A quick google search located a lot of documents
This is a quote from the following document:
"If your client's OBP does not support WAN boot, you can install with a Solaris 10 Software - 1 CD inserted in the client's CD-ROM drive. When you use a local CD, the client retrieves the wanboot program from the local media, rather than from the WAN boot server."
http://docs.sun.com/app/docs/doc/817-5504/6mkv4nh7b?a=view
There is even a howto on a 3rd-party page
http://solaris10es.blogspot.com/2006/03/guide-to-wan-boot-with-solaris-10.html
Michael