Ethernet, IP Addresses, Subnet Masks, Gateways & DHCP

Est. 60 minCompetency: Explain IP addressing, subnets, gateways, and DHCP for AV.

Learning objectives

Explain IP addresses, subnet masks, and the network/p host split.
Describe the default gateway and its role.
Distinguish static vs DHCP addressing for AV devices.
Read and write a small IP plan.

Vocabulary

IP address: A device's numeric address on a network (e.g. 192.168.10.20).
Subnet mask: Splits an address into network and host parts (e.g. /24 = 255.255.255.0).
Gateway: The router address a device uses to reach other networks.
DHCP: A service that hands out addresses automatically.
Static IP: A fixed address assigned manually, not via DHCP.
VLAN: A virtual LAN separating traffic at the switch.

Lesson content

Every networked AV device — control processor, DSP, codec, Dante endpoint, AV-over-IP encoder — needs an IP address, a subnet mask, and usually a gateway. Getting these right is the first network step.

IP address and subnet mask

Address : 192.168.10.20
Mask    : 255.255.255.0  (/24)
Network : 192.168.10.0    (the subnet)
Host    : .20             (this device on that subnet)

The mask tells the device which addresses are on its local subnet (talk directly) and which must go through the gateway. A /24 mask gives 254 usable host addresses (.1–.254).

Gateway and routing

The default gateway is the router that forwards traffic to other networks.
AV devices on one subnet talk directly; reaching another subnet goes through the gateway.
For an isolated AV network you may not need a gateway, but set it to match the plan.

Static vs DHCP

Static — fixed addresses for control processors, DSPs, codecs, Dante endpoints, switch management. AV infrastructure should not move.
DHCP — fine for laptops and guest devices; reservations can pin specific MACs to an address.
Never let an AV control device depend on a DHCP lease that could change.

Plan the IP space first

Pick a subnet, reserve a range for AV infrastructure (e.g. .10–.99 for devices, .200+ for management), and keep a spreadsheet of every address, MAC, and device. That sheet is the network's equipment schedule.

Field caution — duplicate IPs

Two devices with the same static IP cause intermittent faults that look like magic. Keep the IP plan current and reserve each address exactly once.

Worked example

AV network plan: subnet 10.20.30.0/24, gateway 10.20.30.1. Control processor .10, DSP .11, codec .12, Dante interface .13, touchpanel .14 (DHCP reservation), switch .250. Every address logged in the IP schedule.

Implementation checklist

✓Subnet chosen and mask understood (/24 for most small AV networks).
✓Gateway set consistently across devices.
✓AV infrastructure on static IPs; laptops may use DHCP.
✓IP schedule maintained; no duplicate addresses.

Downloadable study guide

study-guide.txtcopy-paste ready

01. IP + mask = network/host split; /24 gives 254 hosts.
02. Gateway routes traffic to other networks.
03. AV infrastructure uses static IPs; DHCP for guests and reservations.
04. Keep an IP schedule; duplicate IPs cause intermittent faults.