Hello Vishwa,
http://www.cisco.com/en/US/docs/switches/lan/catalyst6500/ios/12.2SX/configuration/guide/vss.html
only 67xx modules can be used and these modules don't support POE.
The virtual switching system requires 67xx series switching modules.
The virtual switching system does not support classic, CEF256 or dCEF256 switching modules. In virtual switch mode, unsupported switching modules remain powered off.
The two supervisor engines must match exactly
The VSS is targeted for data center.
the new release 12.2SXI should support service modules and MPLS.
first release in 12.2SXH didn't support IPv6 and MPLS and most of service modules.
Hope to help
Giuseppe
