Power over Ethernet (PoE): Fuel for the Cameras
Understanding PoE Types
| PoE Standard | Power at Device | Typical Use |
| IEEE 802.3af (PoE) | 12–15 W | Small domes, indoor fisheyes |
| IEEE 802.3at (PoE +) | 25–30 W | 4 K bullets with IR, basic PTZ |
| IEEE 802.3bt (PoE ++) | 60–90 W | Full-size PTZ, heaters, multi-sensor units |
Most business cameras sit comfortably under 15 W; allocate 20 W per port to stay safe. A 24-port PoE+ switch with a 370 W budget supports roughly eighteen 20 W loads—allow headroom for night-time IR peaks.
Quick tip: Check total and per-port budgets—two switches may claim the same wattage but differ wildly once all ports run at PoE ++.
Mid-Span Injectors vs New Switches
Injectors add power to individual links when switch upgrades are not yet budget-friendly. They work, but multiply wall-warts and make fault-finding harder. When more than eight injectors crop up in one rack, replacing the switch is usually cheaper and neater.
Switching Capacity: Moving the Megabits
Bandwidth Maths—The Friendly Version
A single 4 MP camera at 15 fps, H.265 compression, streams roughly 4 Mb/s. Ten such cameras peak at 40 Mb/s—comfortable on any 1 Gb uplink. Trouble starts when dozens of UHD channels share the same path as Wi-Fi, Teams calls and backup jobs.
Plan for peaks: shift changes, sports events on the office TV, anything pushing more traffic. If CCTV alone exceeds 60 % of a gigabit uplink, step up to 10 Gb/s on the core or ring in an extra aggregation switch.
For detailed number-crunching, our 4 K Storage and Bandwidth Guide includes a hands-on formula.
Uplink and Stack Design
Star-topology works for small offices: each access-layer switch trunks to the core. Larger estates gain resilience by stacking access switches (one virtual chassis) then dual-homing to a pair of core switches. If one link fails, cameras stay online.
Switch vendors sell licencing tiers; make sure multicast and QoS features are enabled in your SKU or you may pay later to unlock them.
Logical Network Design: Keeping Traffic Clean and Secure
Dedicated CCTV VLAN
Segregating video traffic prevents camera chatter eating office bandwidth and adds a firewall point. The CCTV VLAN needs to talk to:
- The recorder or VMS server
- Time servers (NTP)
- VPN gateway if remote viewing is required
Block everything else. If cameras integrate with access control or alarms, permit only those specific IPs and ports.
IP Addressing and Naming
Static IPs beat DHCP for cameras—you always know where to find “Main-Lobby-Cam”. Reserve a tidy block (e.g., 10.10.50.0/24) and document in a spreadsheet or IPAM tool.
Quality of Service (QoS)
Most networks cope without fancy QoS; just put CCTV on its own VLAN. If WAN back-haul is tight, set video to a lower priority than VoIP but higher than guest Wi-Fi. Simple, readable rules beat default factory settings you never verify.
