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Multicast Switching Protocol


Overview

Switching sources in a Just Add Power Multicast Switching system involves changing the multicast IP of the Receiver - called a Channel - to match the multicast IP of the Transmitter it wants to watch.

Changing the Channel in a Just Add Power Multicast Switching system can be done in various ways depending on the needs of the control system or end user.


Requirements

  1. Only compatible with 3G devices. 2G systems should instead reference Hostname Switching
  2. justOS firmware B2.0.x or greater
  3. All units in the same VLAN with the same IP scheme.

Please see the article on Multicast Switching for Single VLAN Implementations for information on how to setup the network.


Concept

An audio/video signal in a Multicast Switching system is distributed according to the multicast IP assigned to the signal. The full multicast IP is distilled down to a single Channel number for simplicity of programming. Audio and video have separate multicast IPs, making audio and video separately routable.

Each Transmitter has a unique multicast IP that distinguishes it from all other Transmitters on the network.

The multicast IP of a Receiver is altered to match the multicast IP of the Transmitter it wants to watch.

Default Multicast IPs

Basic Mode - audio and video switch together (default)

  • Video - 239.92.0.0
  • Audio - 239.92.0.0

Advanced Mode - audio and video switch together or separately

  • Video - 239.92.0.0
  • Audio - 239.93.0.0

Multicast IP to Channel Translation

The first 2 octets of the multicast IP must be the same for all devices. The first octet can be changed, but must be the same value on all devices. The second octet is used to distinguish between different services - audio or video - on the same unit.

The second 2 octets are unique to each Transmitter and identify it on the network. They directly relate to the Channel number of the Transmitter.

  • Channel numbers are integers ranging from 0 to 9999
  • The 4-digit Channel translates to the last 2 octets of the multicast IP:
    • Channel 0000 --> 239.92.00.00
    • Channel 99 --> 239.92.0.99
    • Channel 100 --> 239.92.1.0
    • Channel 9999 --> 239.92.99.99

Command Line Interface

All commands are case-sensitive.

Set Basic Mode (default)

Set once. All devices must have the same Mode. Audio and video always switch together.

channel mode basic

Set Advanced Mode

Set once. All devices must have the same Mode. Allows audio and video to switch separately

channel mode advanced

Set Audio & Video Channel

Set once on a Transmitter. Send to a Receiver to switch audio and video. Variable X is an integer from 0-9999.

channel X

Set Audio Channel (Advanced mode only)

Set once on a Transmitter. Send to a Receiver to switch audio. Variable X is an integer from 0-9999.

channel -a X

Set Video Channel (Advanced mode only)

Set once on a Transmitter. Send to a Receiver to switch video. Variable X is an integer from 0-9999.
channel -v X

Set Management IP (TX & RX)

Set IP address, subnet mask, and default gateway for network access. Example uses IP 192.168.254.101, mask 255.255.255.0, gateway 192.168.254.1

astparam s ip_mode static;astparam s ipaddr 192.168.254.101;astparam s netmask 255.255.255.0;astparam s gatewayip 192.168.254.1;astparam save


HTTP API

The full HTTP API for justOS is available at https://justaddpower.docs.stoplight.io/


Web Interface

The web interface only allows Basic Mode options

Set Audio & Video Channel

Set once on a Transmitter. Send to a Receiver to switch audio and video. Variable X is an integer from 0-9999.

On the System tab, Assign Channel and select Apply. Channel is updated immediately for a Receiver, and requires reboot to apply to a Transmitter.

Set Management IP (TX & RX)

Set IP address, subnet mask, and default gateway for network access. Example uses IP 192.168.254.101, mask 255.255.255.0, gateway 192.168.254.1

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  • 08-Jul-2020
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