When designing or expanding an IP-based surveillance system in the United States, a common question is: “How do I calculate the total bandwidth (bit rate) required by all my IP cameras?” This is crucial for selecting network equipment (switches, routers), cabling (Cat 5e, Cat 6, fiber), and storage solutions (NVR, server, or NAS).

1. Estimating Individual Camera Streams

Several approaches exist:

• Online Calculators:
• For instance, Axis Design Tool provides a practical approximation based on resolution, frame rate, codec, and scene complexity.
• Reference Tables:
• Example tables are often provided by camera manufacturers. Below is a simplified version for H.264 (Table 20) and MJPEG (Table 21).

Table 20: Bit Rate (Mbit/s) for H.264

Table 21: Bit Rate (Mbit/s) for MJPEG

The choice between MJPEG (intraframe compression) and H.264/H.265 (interframe) depends on:

• The motion complexity of the scene.
• Whether you need detailed per-frame “forensic” analysis (which may favor MJPEG).
• Available bandwidth and storage.

For high-motion scenarios (casinos, busy lobbies, etc.), MJPEG can be preferred because each frame is fully stored — allowing easier detailed frame-by-frame review. However, it consumes more bandwidth. H.264 is more efficient but heavily depends on scene motion and can double or triple the bit rate under high-activity conditions.

Note: In low-light conditions, camera noise may increase data rates (especially in H.264/H.265). Consider using digital noise reduction (DNR) features to mitigate this.

2. Total System Bandwidth

If each camera outputs A(i, j) streams, then the aggregate bit rate BBB for n cameras, each possibly generating k streams (main stream, sub-stream, etc.), is:

However, in practical IP cameras, the so-called multiple “sub-streams” are multiplexed into a single physical data flow at the IP layer. For safety, we increase the calculated total by ~30% to account for peak fluctuations due to scene motion:

Bmax⁡=1.3×B.B_{\max} = 1.3 \times B.Bmax​=1.3×B.

Allocating Bandwidth per Switch Port

After determining your total system bit rate, you must ensure each switch port can handle the camera traffic without exceeding its maximum throughput. Basic guidelines:

• Simple Fast Ethernet Switches (100 Mb/s):
• Realistically, you cannot push 100 Mb/s of continuous video on every port simultaneously. The “switch fabric” capacity must be considered.
• In half-duplex or full-duplex modes, overhead exists. Formulas [3], [4], [5], [6] in the text approximate the maximum safe throughput per port, factoring in overhead (0.7 safety margin, 1.12 or 1.24 overhead coefficients for half/full duplex).

Example: Full-Duplex 8-Port Switch (100 Mb/s Ports)

A simplified formula shows each port can handle about 8.9 Mb/s of stable video if all 8 ports are in use. This might be enough for cameras streaming 6–8 Mb/s in typical H.264. Exceeding that can cause dropped frames or congestion.

For bigger systems, Gigabit (1000 Mb/s) or combo/up-link ports are used so the aggregated data from multiple 100 Mb/s ports can trunk at higher rates to the NVR.

Example: Designing a 56-Camera System

• Each camera is 2.1 MP (1920×1080) using H.264 at 24 fps, referencing Table 20: about 6.51 Mb/s per camera.
• For 56 cameras: total ~364.6 Mb/s.
• Add 30% overhead → ~473.9 Mb/s.
• The design uses a 1 Gb/s backbone. 473.9 Mb/s < 1 Gb/s, so a single LAN can handle all traffic. No additional subnet is needed from a pure bandwidth perspective.

(In real designs, you might subdivide cameras logically or for security reasons.)

Remote/Additional Viewing Workstations

Modern surveillance often needs:

• Remote access over the Internet.
• Additional local workstations for specialized monitoring (supervisor’s office, public viewing screens, etc.).

Each workstation can pull a sub-stream or main stream depending on local needs. Properly planning bit rates ensures no single switch port or trunk is overloaded.

Network Equipment Setup (IP Addresses, Gateways, DNS)

When setting up IP cameras, NVRs, and network gear (routers, switches), follow these rules:

• IP Address: Ensure each device has a unique address in the correct subnet.
• Gateway: The IP of the router or aggregator device leading to the next network (often the NVR or main router).
• DNS: Usually the router’s address if internet-based name resolution is needed, or left blank if purely local.

For instance, you might do:

Note: The exact addresses and netmasks vary. This ensures all cameras send their streams to 192.168.1.1 (the NVR), while the NVR uses 192.168.1.10 (router) for external connections.