H.323 Multiplex Feature |
The purpose of the H.323 Multiplex (mux) feature is to open a single TCP socket in order to send H.323 Q.931 messages between two Tenor Gateways. Q.931 messages for multiple calls are sent over this single socket. Each H.323 call is identified over the mux socket by its call reference value (CRV).
Note
This method is only used to transport H.323/Q.931 signaling messages. The media will still be negotiated to use its standard port range.
Typically, one of the Tenor Gateways is behind a firewall, while the other Gateway (or Call Relay) is on the public side of the network. Upon proper configuration, the Gateway on the private side of the network (called the Client) initiates a TCP connect to the IP address/port of the public Gateway (called the Server). Once this socket has been connected, all H.323 calls between the two Gateways will be placed over the mux socket. This feature cuts back on the number of ports that need to be opened up in the firewall in order to accommodate H.323.
In order for multiple Gateways located behind a single firewall to talk to the same Server, a protocol has been defined to send the MAC address of the Client to the Server as soon as the mux socket is connected. The message to accomplish this is called Mux Register. The Server uses the MAC address sent in the Register message to distinguish which of its mux sockets should be used to send a particular message.