IP Addresses and Subnet Masks

IP Addresses and Subnets can be confusing at times, especially when using IP Address ranges which are less common. This guide will help you understand how IP Addresses and Subnet Masks work, and we offer some recommended settings. This guide only discusses IPv4 addresses. Shure devices do not support IPv6 at this time.

What is an IP Address?

An IP Address is a unique address for a device which sends and receives network traffic on a network. Some devices may have more than one IP Address, because they have multiple internal components which need to communicate, or because they need to operate on multiple networks at the same time.

An IP Address consists of four numbers called octets that are separated by periods. Each number can range from 0 to 255. An example of an IP Address is: 192.168.1.20.

There are four very common ranges of IP addresses which are used for private networks. These addresses cannot be accessed over the Internet, and so are suitable for AV networks. If you are not sure what range of addresses to use, you should use one of these:

• 192.168.0.0 to 192.168.255.255 (65,536 possible IP addresses)
• 172.16.0.0 to 172.31.0.0 (1,048,576 possible IP addresses)
• 10.0.0.0 to 10.255.255.255 (16,777,216 possible IP addresses)
• 169.254.0.0 to 169.254.255.255* (65,536 possible IP addresses)

Note: The last range, 169.254.x.x, is a special IP address range that is reserved for devices to self-assign an address. You generally do not manually assign addresses in this range, and they are not "handed out" by a switch, device, or server. Devices give themselves an address in this range when no DHCP server is present and a static IP address is not configured.

There are some additional IP Addresses and ranges of IP Addresses you should be aware of:

• 0.0.0.0: No IP Address. This is sometimes entered in the Gateway field when you want a network to be isolated. See the section on Subnets and Gateways below.
• 127.0.0.1 (and 127.0.0.0-127.255.255.255): This address always sends data back to the device that sent it. It's sometimes called localhost or a loopback address. Do not ever assign an address beginning with 127 to a device.
• 224.0.0.0-239.255.255.255: These are Multicast IP Addresses. See Multicast and IGMP In Depth for more information on Multicast IP traffic. You can't assign these addresses to a device as they are not valid device addresses.
• Any other address range not mentioned: other IP addresses should be assumed to be part of an enterprise network which is connected to the public Internet. Do not use those addresses unless your IT department directs you to do so.

Subnet Masks

A Subnet Mask defines which range of IP Addresses are within a local network, and which ones are not. Subnet masks always work from left to right. Devices are said to be within the same subnet if their IP Address starts with the same digits, but ends with a different set of digits.

Sometimes, it's easy to tell which part of an IP address is part of the local network and which is not (when the subnet mask consists only sections that are 255 and 0), but sometimes it may not be as clear.

If the subnet mask is 255.255.255.0, then the first three octets of all devices must be the same. The 4th octet must be different and unique. A maximum of 254 devices can be used in this subnet.

If the subnet mask is 255.255.0.0, then the first two octets of all devices must be the same. The combination of the last two octets must be different and unique. 65,534 devices can be used in this subnet.

The very first address and very last address in a subnet are specially reserved addresses and cannot be assigned to devices. Devices that are within the same subnet will be able to communicate with one another, but a gateway is required to communicate with devices in different subnets.

Gateways (or Routers)

When traffic is intended for a device outside of the subnet, it is sent to the gateway to be routed to the correct destination. The gateway is a device on the network which has multiple networks configured. For example, a gateway on a home network generally sees the local network (e.g., 192.168.0.x) as well as the ISP (Internet Service Provider) network. The gateway takes local traffic for the internet and sends it along to the ISP, and then sends the response back to the device that originally sent the request.

Devices on isolated networks, such as AV networks which do not connect to the Internet) should not have a gateway assigned. This can cause unexpected behavior because devices may attempt to contact the non-existent gateway. If the field must be filled in, enter 0.0.0.0.

Recommended Settings

Generally, we recommend you set your devices for Automatic or DHCP mode. A DHCP server on the network isn't required, but it is fine if one is present. For Dante-enabled devices, both the Shure Control and Network Audio addresses should be set to Automatic or DHCP (don't set one to Static and the other to Automatic).

• If a DHCP server is present, devices will get an IP Address in the DHCP range like 192.168.1.x.
• If no DHCP server is present, devices will get an IP address in the 169.254.x.x range with a 255.255.0.0 subnet mask. This is perfectly fine.

Static IP Addresses

If you must use static IP addresses for your network, be sure that both Shure Control and Network Audio address for all devices are within the same subnet, and that all devices have unique IP addresses. We recommend that you maintain a list of all IP addresses in use to avoid conflicts. Do not assign a gateway address if there is no internet connection.

Separating Traffic
In some cases, it is desired to separate Dante traffic from Control traffic. This can be done with some Shure devices which have multiple Ethernet ports by setting them to the Split mode. However, it is not possible to just configure IP addresses in different ranges in an attempt to separate traffic on the same switch or VLAN. This can lead to a number of issues, including devices which cannot communicate with one another, and will not prevent multicast and broadcast traffic from reaching undesired destinations in many situations.