oh alright, I guess I need to continue my documentation 
So basically, with SAProuter you can connect SAP to a customer's SAP or a SAP landscape (from client A) to the SAP of the VAR for exemple.
It all goes through the Internet, all you need for two system to connect them is that they both have SAProute ?
A basic scheme , in a VAR scenario for exemple, could then be "SAP solution of client A -> Customer A Solman -> customer SAProuter -> Internet -> VAR SAProuter -> VAR Solman -> VAR SAP solution" ?
And if I got it right, SNC (Secure Network Connection) is there to encripte that connection, especially when it goes over internet