Networking and Signal Distribution
What this domain tests
This domain tests AV-over-IP and baseband distribution: IP addressing, VLANs, QoS, multicast, IGMP snooping, bandwidth, and distance limits for HDBaseT, SDI, and fiber. Expect items that require you to decide whether a link is feasible and how to configure the network.
Core rules
- AV-over-IP uses IP packets; multicast streams require IGMP snooping on switches to avoid flooding all ports.
- QoS prioritizes latency-sensitive AV traffic, often using DSCP markings; a separate VLAN can isolate AV from corporate data but still needs correct routing and multicast configuration.
- HDBaseT commonly carries video, audio, control, and power over twisted-pair copper up to about 100 m; longer runs need fiber or an active extension.
- SDI is point-to-point coax with defined bitrates (3G, 6G, 12G) and limited equalization distance depending on cable and rate.
- Uncompressed 4K60 4:2:2 10-bit exceeds 1 GbE capacity and generally requires 10 GbE or compressed AV-over-IP.
Worked example
An uncompressed 4K60 signal uses 3840 × 2160 pixels, 60 frames/s, and an average of 20 bits per pixel for 4:2:2 10-bit. Estimate the active-pixel bitrate.
- Pixels per frame = 3840 × 2160 = 8,294,400.
- Pixels per second = 8,294,400 × 60 = 497,664,000.
- Bitrate = 497,664,000 × 20 = 9,953,280,000 bit/s ≈ 9.95 Gb/s. Reasoning: blanking and encoding overhead raise the actual link rate, so this signal does not fit on 1 GbE and needs 10 GbE or compression.
Traps
- Assuming a 1 GbE link can carry an uncompressed 4K stream.
- Forgetting IGMP snooping and flooding multicast to every port.
- Mixing VLAN isolation with routing requirements for control and management.
- Ignoring distance limits for copper HDBaseT or high-rate SDI.
- Marking QoS but not configuring queues on the switch.