SSL ENABLED and USE SECURITY SERVICES, will affect client connection?

Hi Folks

Our sybase 15.7 server need enable USE SECURITY SERVICES and SSL ENABLED , (both need change from 0 to 1) . This is a request by new security policy.

My concern is we have over hundreds of desktop user use open client connect to this server, do we have to make change to the client connection ?can those client still use NON-SSL regular (old) connection?

Or put in another word, after we enable those two config value, is SSL a must for each client connection, or just an option? 

Thanks in advance!