NETWORK SWITCHES FOR NETWORK CAMERAS, HOW TO CHOOSE?

Network cameras become more and more popular in video surveillance application, how to choose the right network switches that meet the high definition video surveillance data switching becomes very important. 

Three-layered hierarchical network

According to network topology structure, a medium and large video surveillance system requires adoption of three-layered hierarchical model: Access layer, convergence/distribution layer, core layer, each layer's network performance and required bandwidth is different, the selected network switch is also different.

Access layer

Users can choose 8 ports or 16 ports 10/100Mbps network switch, can connect the number of network cameras is 6-10 pieces.

As we know, the real bandwidth of network switch is the 50%-70% of theoretical value, thus a 100Mbps network switch real bandwidth is 50 Mbps-70 Mbps. 4M*12=48M, so a 100Mbps network switch can connect to max. 12 sets of IP cameras with 720p resolution. Meanwhile, we need to consider the fact that IP cameras adopt dynamic encoding method, network camera's peak bitrate may exceed 4Mbps, also need to consider the bandwidth redundancy, so a 10/100Mbps network switch should connect not more than 8 pieces network cameras, more than 8 units of  network cameras, it's recommended to use a Gigabit network switch.

Convergence layer

The network switch used in convergence layer requires much higher performance than network switches in access layer, can choose network switches equipped Gigabit uplink ports. This network switch 10/100 Mbps ports connect to network switch (of access layer), 10/100/1000Mbps (Gigabit) uplink port connect to network switches belong to core layer. The number of maximum connected network cameras should be within 30 sets.

Based on one 720p network camera requires 4Mbps, each 10/100Mbps network switch connects to 6 pieces 720p network cameras, convergence layer network switches connect to five sets of access layer network switches. The total bandwidth in convergence layer is 4M*6*5 = 120M, therefore convergence layer network switches need to have Gigabit uplink ports.

Core layer

Network switches in core player are crucial for the entire video surveillance system. It downlinks network switches from the convergence layer,uplinks video surveillance platform, storage server, NAS etc equipment, suggesting to use the layer 3 Gigabit core network switch, the number of total network cameras exceed 150 sets should consider to use the layer 3 ten-gigabit network switch.

Two important parameters

1. Backplane bandwidth

Backplane bandwidth, refers to the bus bandwidth/speed available for communication between the line cards and the SUP module in a chassis-based switch. It represents the total switching bandwidth of the network switch, its unit is Gbps, also called the switching bandwidth. The higher the backplane bandwidth, the stronger its data processing capability.

Backplane bandwidth calculation method: Number of ports x ports speed x 2 = Backplane bandwidth.

Taking Huawei S1724G network switch as an example, it has 24x Gigabit ports, its backplane bandwidth = 24 x 1000 x 2 / 1000 = 48Gbps.

Backplane bandwidth ≤ nominal backplane bandwidth, this means this network switch is wire-speed type, also known as non-blocking.

2. Forwarding performance

Packet forwarding rate, also known as port throughput, refers to the packet forwarding capability of each port in the network switch, unit normally used pps (packets per second( to measure. Generally, low-end router's packet forwarding rate is only several K to tens of Kpps, and high-end routers can reach tens Mpps (million packets per second) or even hundreds Mpps.

Packet forwarding rate calculation method: Number of Gigabit ports x 1.488Mpbs + Number of 100Mbps ports x 0.1488Mbps = Packet forwarding rate.

Taking Huawei S2700-26TP-SI as an example, it has 24x 100Mbps ports, 2x Gigabit Uplink ports.

Its packet forwarding rate = 2x 1.488Mbps + 24 x 0.1488Mpps = 6.5472Mpps.

The total packet forwarding rate ≤ nominal packet forwarding rate, then the switching equipment is wire-speed forwarding, also known as non-blocking.

HOME security burglar ALARM SYSTEM - 6 THINGS YOU SHOULD KNOW BY NOW

Security industry mainly includes alarm monitoring, video surveillance, access control, video intercom etc sectors. Undoubtedly, video surveillance contributes more than 70% market share. Nowadays, it becomes the fast growing business in global security market, video surveillance is evolving from analog standard definition to digital high definition. 

Network alarm system is far too flawed to be Reliable

WiFi or Internet connectivity technology can allow security system to transmit alarm signals through your home Internet connection. Unfortunately, the current technology is far too flawed to be reliable.  Alarm connection is crucial important for home security system. Once an alarm occurs, the system should instantly send alarm signals to alarm monitoring centre or key holders. Currently, there are three main technologies have been used in alarm communication, they are telephone line, GSM/3G/4G cellular, Internet. 

Each methods has pros and cons:

• Telephone line: wired connection, vulnerable to be cut by a smart intruder, not portable, connection speed is slow
• GSM/3G/4G cellular: wireless connection, portable, connection speed is medium
• Internet / Network: wired connection, likely to fail when electricity/network outage and router stops working, or IP address has been changed, connection speed is fast.

What's difference between magnetic contact and PIR motion sensor?

A  home security system will include one alarm control panel and some security sensors. Users can choose diversity security sensors that used to detect different events. Magnetic contact, has many different names such as Door/Window sensor, reed switch, entry-point sensors etc. Magnetic contact is suitable for all open/close cabinet objects including doors, windows, drawers, wardrobes, safety deposit boxes, gun boxes etc. Magnetic contacts are inexpensive, very reliable, and in most cases out of sight. Magnetic contacts are inexpensive, very reliable, and in most cases out of sight. They are suitable for perimeter protection as the first line of defense in the burglar alarm system. While PIR motion sensor is widely used in interior motion detection. It adopts passive infra-red detection theory to sense moving objects. PIR motion sensors can protect a large space area. While PIR's and other interior detectors are an excellent back up, it is the contact that immediately triggers the alarm system when the door or window is open. Contacts should be used on all entry sights because a PIR will pick up the intruder after they are inside.

DOOR SENSOR

SMOKE SENSOR

PIR SENSOR

 

What is AHD CAMERA?

AHD CCTV is an analog high definition closed-circuit television video surveillance standard that uses coax cable to transmit HD video from security cameras to DVRs. AHD supports 720p and 1080p HD video resolutions.

What type of cable do AHD Cameras use?

AHD CCTV cameras are connected to DVRs using the same type of coaxial cable as traditional analog CCTV cameras , typically RG59 or RG6 coax cable. One of the advantages of AHD over HD-SDI cameras (another HD over coax security camera standard), is that RG59 coax cable can be run long distances without video loss. So far in our experience, installers can reliably use RG69 coax cable up to a max distance of 800 feet for AHD cameras.  AHD cameras can also use UTP cable with video baluns to run cable up to 320 Meters / 960 feet with CAT5 cable.

AHD vs 960H Video Resolution

The below images compare a video surveillance photo capture by a 960H CCTV camera with 720p and 1080p AHD CCTV cameras. The first two cameras where connected to an iDVR-E8 hybrid analog / AHD CCTV DVR to capture the images. The 1080p camera was connected to an iDVR-PRO AHD-TVI / anlog CCTV hybrid DVR.

The analog and 720p AHD camera were both displayed full screen at 720p resolution when the image was captured. The 1080p AHD camera was displayed at 1080p resolution.  

960H RESOLUTION IMAGE

AHD RESOLUTION IMAGE (720p AHD)