The Media Router role is the central role that handles all stream requests (audio and video) in Security Center. It establishes streaming sessions between the stream source, such as a camera or an Archiver, and its requesters (client applications). Routing decisions are based on the location (IP address) and the transmission capabilities of all parties involved (source, destinations, networks, and servers).
Role of the Media Router
The Media Router ensures all video streams use the best route to get to their destinations, while performing any necessary transport transformation, for example, from unicast to multicast, or from IPv4 to IPv6.
Only a single instance of the Media Router role is permitted per system.
Network security
The Media Router role has a default RTSP port of 554, and its redirectors have a default RTSP port of 560 and a default RTP port of 960. Archiver roles have two default RTSP ports: 555 and 605. If the Media Router, redirector, and Archiver are hosted on the same server, each of these ports must be unique. For all ports requirements, see Ports used by Omnicast™ applications in Security Center.
If multiple Archiver roles are created on the same server, they must each have different RTSP ports. Otherwise, the role entity turns yellow and an Entity warning event is generated.
Multicast optimization
Client applications can only request multicast streams by IP address from the router, not by port number. Therefore, although a client application listens only on a specific port, all stream sources sharing the same IP address are sent by the router. If your system uses Federation™, there is a good chance that a federated camera would be assigned the same IP address, with a different port, as a local camera. When a client requests a multicast stream from a local camera while a federated camera assigned to the same IP address is in use, both streams are sent to the client, although only one is needed. The likelyhood of this conflict is greatly increased if, for example, you record the federated stream continuously.
To avoid wasting network bandwidth, the Media Router uses two separate ranges of IP addresses, one for local streams and another for federated streams. Each range of multicast IP addresses is defined by a Start address and a specific port number.
Overcoming Windows multicast performance issue
There is a known Windows limitation that puts a cap on the bandwidth of a single port at around 100 Mbps. For systems with a lot of multicast traffic, a second optimization is available, and that is to increment the port number for each new multicast address. For each new multicast address, the port number is incremented by 2. Even port numbers are used for data transmission, while odd port numbers are used for RTCP control messages. This option is available on the Properties page of the Media Router.
For more information, see Best practices for configuring Multicast in your network for Security Center.