One large product group that is important to know about when setting up a camera system for IP surveillance is switches. A network switch, or switching hub, is a computer networking device that connects network segments. The network switch plays an integral part in most modern Ethernet local area networks (LANs), and a network can have more than one switch. The switch only sends data to the receiver that is supposed to have access to the given information. In this way, a network doesn’t overload when data is sent. It also means higher security as it is hard to gain access to information not meant for another computer.
Non-blocking and wired-speed both refer to the performance of an Ethernet switch. With a 24 port 10/100/1000 switch, if each port is 2G in full duplex mode, then 24 ports means the device is a 48G switch. When this volume of data is passed through the switch, the switch performance can be categorised as non-blocking or wired speed. If the switch is connected to another switch, or to a server that uses network storage or transfers, then non-blocking is essential. Yet, how this is accomplished is up to the vendor’s switch design. The user can only rely on the data provided by the vendor.
Layer 2 switching (or Data Link layer switching) is the process of using devices’ MAC addresses on a LAN to segment a network. Switches and bridges are used for Layer 2 switching. They break up one large collision domain into multiple smaller ones. In this article, we will examine a few important features on the switches used for CCTV projects.
We need to consider the following points when investing in a Switch.
– How many CCTV cameras will be connected?
– Will the system run continuously or is it motion/event triggered?
– Are certain CCTV cameras inactive for any periods?
– Does the switch allow for system expansions and upgrades?
– Are we going to multicast the surveillance video?
– Is PoE (Power over Ethernet) required?
– What peripheral devices are going to be used?
100Mbps ports: In a CCTV project the cameras require around 2.5 Mbps for full HD video streaming (1920 x 1080) at 15 FPS (the default setting for most cameras). If you use a 24 ports switch with 100 Mbps transmission per port, that means you will use only 2.5% of the capacity of each port per video stream.
Gigabit ports: In most cases the switches need to have ports with only 100 Mbps to connect the cameras, however, for the connection between two switches or with the server you can use the Gigabit port that allows to sum up the traffic of the 24 ports in a single port.
Bandwidth: Usually there are switches with 24 – 100M bps ports and 4 1000 – Mbps ports with total bandwidth of 12.8 Gbps, this means that we could use the maximum capacity of all ports without problems, but we already know that we don’t need that much for cameras.
Fiber Optic: Some switch models have fiber optic module inputs to allow connections over long distances.
Redundancy: If you need to use redundancy in your project, the switch has the ability to work with standard STP and RTSP protocols that guarantee high speed redundancy.
Virtual LAN (VLAN): In projects that need to isolate broadcast traffic and implement security, VLANs are very useful, most switches allow you to manage a minimum of 256 VLANs with the 802.1Q protocol standard.
Multicast: When it is necessary to work with multicast streaming the switch must allow the use of specific protocols such as IGMP snooping v1, v2 or v3 or IGMP querier.
COS and QoS: In a network with different devices, sometimes it is necessary to prioritize some of them, in which case the use of COS (Cost of Service) and Quality of Service (QoS) technology must be available on the switch.
Security: To implement security it is recommended to have some features such as 802.1X, Radius and TACACs, so only the cameras and monitoring/recording servers can connect to the network. Make sure the switch has the necessary technology to allow this type of security.
Monitoring: It is possible to monitor the use of the switch with the standard protocol SNMP v1, v2, v3 as long as the switch supports these protocols, it is also interesting to have the monitoring feature of the packets that traffic through the use of port mirroring.
Switches are not only boxes with ports available to connect cables, there are a multitude of features that can be used to improve your project. Be aware of this to make the best use of the equipment. You check out Recommended Network Switches
in this link.
