What is a network switch?
A network switch is a device that operates at the Data Link layer of theOSL model—Layer 2. It takes in packets being sent by devices that are connected to its physical ports and sends them out again, but only through the ports that lead to the devices the packets are intended to reach. They can also operate at the network layer–Layer 3 where routing occurs.
Switches are a common component of networks based on ethernet fibre channel Asynchronous Transfer Mode (ATM), and InfiniBand among others. In general, though, most switches today use ethernet.
A network switch connects devices within a network (often a local area network or LAN*) and forwards data packets to and from those devices. Unlike a router, a switch only sends data to the single device it is intended for (which may be another switch, a router, or a user’s computer), not to networks of multiple devices.
Switches are networking devices operating at layer 2 or a data link layer of the OSI model. They connect devices in a network and use packet switching to send, receive or forward data packets or data frames over the network.
A switch has many ports, to which computers are plugged in. When a data frame arrives at any port of a network switch, it examines the destination address, performs necessary checks and sends the frame to the corresponding device(s).It supports unicast, multicast as well as broadcast communications.
Features of Switches
- A switch operates in the layer 2, i.e. data link layer of the OSI model.
- It is an intelligent network device that can be conceived as a multiport network bridge.
- It uses MAC addresses (addresses of medium access control sublayer) to send data packets to selected destination ports.
- It uses packet switching technique to receive and forward data packets from the source to the destination device.
- It is supports unicast (one-to-one), multicast (one-to-many) and broadcast (one-to-all) communications.
- Transmission mode is full duplex, i.e. communication in the channel occurs in both the directions at the same time. Due to this, collisions do not occur.
- Switches are active devices, equipped with network software and network management capabilities.
- Switches can perform some error checking before forwarding data to the destined port.
- The number of ports is higher – 24/48.
Types of Switches
There are variety of switches that can be broadly categorised into 4 types −
- Unmanaged Switch − These are inexpensive switches commonly used in home networks and small businesses. They can be set up by simply plugging in to the network, after which they instantly start operating. When more devices needs to be added, more switches are simply added by this plug and play method. They are referred to as u managed since they do not require to be configured or monitored.
- Managed Switch − These are costly switches that are used in organisations with large and complex networks, since they can be customized to augment the functionalities of a standard switch. The augmented features may be QoS (Quality of Service) like higher security levels, better precision control and complete network management. Despite their cost, they are preferred in growing organizations due to their scalability and flexibility. Simple Network Management Protocol (SNMP) is used for configuring managed switches.
- LAN Switch − Local Area Network (LAN) switches connects devices in the internal LAN of an organization. They are also referred as Ethernet switches or data switches. These switches are particularly helpful in reducing network congestion or bottlenecks. They allocate bandwidth in a manner so that there is no overlapping of data packets in a network.
- PoE Switch − Power over Ethernet (PoE) switches are used in PoE Gogabit Ethernets. PoE technology combine data and power transmission over the same cable so that devices connected to it can receive both electricity as well as data over the same line. PoE switches offer greater flexibility and simplifies the cabling connections
Benefits or advantages of Switches
Following are the benefits or advantages of Switches:
➨They increase the available bandwidth of the network.
➨They help in reducing workload on individual host PCs.
➨They increase the performance of the network.
➨Networks which use switches will have less frame collisions. This is due to the fact that switches create collision domains for each connection.
➨Switches can be connected directly to workstations.
Drawbacks or disadvantages of Switches
Following are the disadvantages of Switches:
➨They are more expensive compare to network bridges.
➨Network connectivity issues are difficult to be traced through the network switch.
➨Broadcast traffic may be troublesome.
➨If switches are in promiscuous mode, they are vulnerable to security attacks e.g. spoofing IP address or capturing of ethernet frames.
➨Proper design and configuration is needed in order to handle multicast packets.
➨While limiting broadcasts, they are not as good as routers.
DIFFERENCES BETWEEN ROUTERS AND SWITCHES
Router and Switch are both network connecting devices. Router works at network layer and is responsibe to find the shortest path for a packet whereas Switch connects various devices in a network. Router connects devices across multiple networks.
Following are the important differences between Router and Switch.
|1||Objective||Router main objective is to connect various networks.||Switch main objective is to connect various devices in a network.|
|2||Layer||Router works in Network Layer.||Switch works in Data Link Layer.|
|3||Usage||Router is used in LAN and MAN.||Switch is used only in LAN.|
|4||Data Format||Router sends data in form of packets.||Switch sends data in form of packets and frames.|
|5||Mode of Transmission||Router follows duplex mode of transmission.||Switch also follows duplex mode of transmission.|
|6||Collision||Less collision in case of Router.||In full duplex mode, no collision happens in switch too.|
|7||NAT Compatability||Compatible with NAT.||Not compatible with NAT.|
|8||Type||Routing type is Adaptive and Non-adaptive routing.||Switching type is Circuit, Packet and Message switching.|
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