RealSystem streaming media protocol details

RealSystem streaming example: UDP to clients

The following example shows the typical client and server connections required for RealSystem streaming. Note that in this example, NetCache receives content from the streaming server over TCP and delivers the content to clients over UDP.

If a firewall did not allow one or more of the required ports, the NetCache appliance would use HTTP encapsulation over TCP port 80 to send data to servers or clients. This scenario is not illustrated.

Understanding RealSystem connection requirements

The following table describes the types of protocols NetCache must service to deliver RealSystem content to clients.

Use the proceeding table to configure the NetCache appliance and associated network devices, such as a switch, router, or firewall, that must pass traffic to and from the NetCache appliance. To ease configuration, the Appliance Manager provides default settings that correspond to the port information provided in the following table.

Protocol	Transport	Explanation	Upstream traffic	Downstream traffic
RTSP	TCP	Real Time Streaming Protocol. Used to coordinate the delivery of streaming media.	Received on NetCache port 554 Sent to port 554	Received on arbitrary NetCache port Sent from port 554 to arbitrary client ports
RDT or PN-TNG	UDP	Real Data Transport. RealNetworks proprietary protocol used for monitoring and feedback.	Received on NetCache port 554 Sent to arbitrarily advertised UDP ports	Received on NetCache port range 6970 to 65000 Sent from NetCache port 554 to arbitrarily advertised UDP ports
RTP	UDP	Real-Time Transport Protocol. Used for data transport for all proxied RealNetworks streams.	N/A	Received on NetCache port range 6970 to 65000 Sent from NetCache port 2000 to arbitrarily advertised UDP ports
HTTP	TCP	HTTP encapsulation is used from NetCache to clients and NetCache to servers when the firewall blocks TCP or UDP.	Received on NetCache port 80 Sent to origin server port 80 Can also be sent from or received on port 8080	Received from origin server port 80 or 3128 Sent from NetCache port 80 or 3128