TCP/UDP relay vs. SOCKS64

["CTO YAN Renxiang" <Renxiang.Yan@alcatel-sbell.com.cn>]

Hi, all,

Both TCP/UDP relay and SOCKS64 are implemented by forwarding connection to a relay server.
TCP/UDP relay is forwarded by router, and relay in relay server. 
SOCKS64 is forwarded in source host, and relay in SOCKS64 server.

Does anyone can tell the essential differences between this two mechanism?
They can be used in which kind of different cases?

Another issue is: 

In RFC 3142, it states: 

   TRT is designed to require no extra modification on IPv6-only
   initiating hosts, nor that on IPv4-only destination hosts. 

but in fact, the host is required modification, e.g. DNS resolver. 


-Renxiang