General Network Guidance¶

Practical Considerations¶

Power over Ethernet and Cables¶

All units work on IEEE 802.3af Standard active Power over Ethernet (abbreviated to PoE).

PoE comes in two ways: either power on the data lines or on the (100mbit)spare lines: Green-GO Digital Intercom products support both. There is also no need to worry about using crossover cables as all devices support MDIX (automatic detection).

Some units can also work with an external power supply (multichannel stations and rack mount interface units). PoE uses a sensing method to check if a connected device needs power. It will only apply power when needed.

There is no need to worry about using crossover cables as all devices support MDIX (automatic detection)

As Green-GO Devices handle audio signals and interface with other audio systems, it very well possible to create ground loops in unexpected manners when using shielded network cables. The easiest way to prevent this is to use unshielded network cables.

Shielded cable will work, but its not necessary and it will improve the chance of ground loops and its associated hums and buzzes

^* any combination of foiled and/or shielded

Bandwidth and Latency¶

By default, the system audio runs at a 32kHz/16bit sample rate providing ~15 kHz of audio bandwidth. The number of active sources determines the network bandwidth used.

An active source is, for example, a device with one or more talks enabled and vox present, the gate threshold is met . Each active source uses about 650kbps, less than 0,7% on a 100Mbps network. In practice this will limit a system to 150 simultaneous active sources on a single config

The audio latency for wired devices is fixed at ten (10) milliseconds for a 32kHz system (headset-to-headset), comparable to standing 3.5 meters away from the person talking (no lip-sync problems).

Quality of Service (QoS) / Class of Service / IEEE 802.1p¶

The Green-GO digital intercom system is designed to work on a shared network. However, as the latency of the Green-GO digital intercom is very low (10 milliseconds), there is a small requirement on the network switches used. The switches need to support Quality of Service (QoS) or IEEE 801.2p. Almost every professional switch supports this, but check the specifications.

VLANs, High Bandwidth Backbones and Multicast¶

The Green-GO digital intercom system can work within a network (LAN) that carries other traffic and protocols. For more reliable operation and minimizing network configuration issues it is however advised to separate traffic using managed switches and VLAN's or a physical isolated network

When deploying a large-scale network with a 1GB or higher backbone that uses a lot of multicast/broadcast (more than ~50Mbit), it is good practice to create a separate VLAN for Green-GO traffic. As Green-GO is based on 100Mbit and multicast technology.

Although networks without IGMP snooping and querying will work fine for smaller setups, larger systems will benefit from correctly setup IGMP snooping especially when other multicast traffic on the same (V)LAN is present. Correctly Setting up IGMP snooping and querying can be complicated especially using multiple brands of switches. Incorrect setup networks will usually cause more problems than solutions. Problems can vary from interrupted audio streams, or groups of devices that can not hear other groups of devices.

Boot up time and Network indication¶

The boot-up time of the devices is less than 3 seconds, but care should be taken as some switches can take up to 30 seconds to bring up the network link (this can be due to a spanning tree functionality of the switches).

Each Green-GO device will indicate if the network connection is ok and other Green-GO devices are visible with the same configuration. The belt packs will have a blue backlight if there is a problem or no other devices are found, the MCX rack and MCXD desktop station will blink, the Setup button will flash red, and the interface units will flash the backlight.

IP addressing¶

Usually, configuring the IP address is NOT needed for the regular operation of the system. The handling of IP addresses is only needed if the Green-GO devices need to communicate with a computer (only for loading new configuration or monitoring and firmware updates). By default the units get a dynamic IP address via DHCP or LLC, a fixed IP address can be set with the Firmware Update program.

Protocols and Ports¶

Device communication¶

• Diffserve (DSCP) at 46 ( RTP / Voice )
• 650kbit/s @32Khz, per engine sending active audio
• ~2.5kbit/s per engine, not sending audio

Application¶

The Green-GO application uses several TCP/UDP ports. In very specific cases, for example with very strict third party firewalls it might be necessary to specifically allow these ports through the firewall: