A network switch directs traffic across a LAN, allowing computers to communicate and share resources. It operates in full-duplex mode, sending traffic discriminatively, making it superior to a hub. Anti-sniffing software can be installed to detect packet sniffers. Network switches increase in price with the number of ports they have. A broadband router with built-in switches and firewalls can be used instead of a standalone switch.
A network switch is the central device in a wired or wireless local area network (LAN). It receives signals from each computer on the network via Ethernet cables in a wired network or radio waves in a wireless LAN. In both cases, the switch directs traffic across the LAN, allowing computers to communicate with each other and share resources.
All computers included in the LAN must contain a network interface card (NIC). The card assigns a unique address to the machine where it is installed. This address is called Medium Access Control (MAC). A wired NIC houses an Ethernet cable, which goes to a port on the back of the network switch. If the NIC is wireless, the card will have a small antenna that carries signals to the wireless switch, which also carries an antenna instead of ports. Whether wireless or wired, the switch acts as a relay, reading incoming traffic packets from various machines and routing the packets to the appropriate MAC address.
A network switch operates in full-duplex mode, which means that a machine on the LAN can receive and transmit data simultaneously. This is much faster than a network hub, an alternative device that serves the same purpose but operates in half-duplex mode, allowing any machine or node to send or receive at any time. Another key difference between a switch and a hub is that the switch sends traffic discriminatively, using addresses to route traffic packets exactly where they should go. A network hub, on the other hand, broadcasts all traffic on the network to all nodes, relying on filters within each machine to drop packets not addressed to it. This makes networks using a hub particularly vulnerable to “packet sniffers” or eavesdropping.
For the above reasons, a network switch is considered superior to a network hub, but the device isn’t foolproof either. It can be “fooled” to accommodate packet sniffers, but the methods used to fool the switch will leave telltale traffic signatures, unlike the passive methods that can be used on a hub. Anti-sniffing software can be installed on a switched network to detect packet sniffers.
Network switches are inexpensive devices, but they increase in price with the number of ports they have. For those with cable modem or DSL service, a broadband router with built-in switches and firewalls can be used in place of a standalone switch.
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