A method and apparatus for providing notification to a client that an access server is on-line during a communication session is disclosed. The client and the access server execute an embedded protocol, such as telnet, to define the communication session. The protocol defines a negotiation-style communication...http://www.google.com.au/patents/US6304905?utm_source=gb-gplus-sharePatent US6304905 - Detecting an active network node using an invalid protocol option
