2.1.2 Ping Message
A Ping Message can be a Ping Request or a Ping Response. A Ping Request MAY<7> be sent from an initiator to an acceptor to determine whether the acceptor is available and can accept a binary protocol sequence connection. An acceptor responds to a Ping Request by sending a Ping Response back to the initiator. All Ping Messages use the Ping Packet (section 2.2.7).
Ping Messages MAY<8> be sent using the UDP or the SPX protocol.
Ping Requests are sent to UDP or SPX port 3527 on the acceptor.<9> The source port used by the initiator can be any UDP or SPX port value. The initiator MUST listen on that source port for the Ping Response.
The acceptor MAY<10> listen for Ping Requests. If an acceptor listens for Ping Requests, it MAY<11> do so on UDP or SPX port 3527. A Ping Response MUST be sent to the UDP or SPX source address and port from which the corresponding Ping Request was sent.