Network Devices-Hub, Switch and Router

A network is a group of multiple networking devices connected together for data sharing. As a group networking devices have a single purpose which securely transfers data as fast as possible. To meet this goal there are several networking devices like bridge, hub, switch, and the router is being used. Here in this article, we will discuss important networking devices.

Hub

Hub is a network technology but not really used in modern networks. In networking, it is just studied because it is helpfulnetwork hub to understand switch if somebody understands it then he can easily understand a switchIt is a device that simply copies a data which received on any port to all its ports.  So, if a packet of data arrives on interface 1 of a 5 port hub, It will blindly copy that data out the interfaces 2 through 5. It’s a common connection point for devices in a network. Different segment of LAN commonly connected to the hub. It was a cheap and quick way to link up multiple computers in the early days.  

The main issue with hubs though is that only one computer can talk at a time.  So, If 2nd computers going to talk at the same time, their traffic would get joined as it was echoed out the other interfaces.  This is called a collision, and it would corrupt the data being transmitted by both computers. So, each computer would have to try again, after a random time period.  This becomes a real problem when the network gets busy or when more than a hand full of computers are on a network.  A switch solves the collision issue. Hub is a single broadcast and single collision domain.

Switch

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An Ethernet Switch is a device which is used to connect multiple computers and devices within  LAN. It is work at Layer Two (Data Link Layer) of the OSI model. Some switches also work at layer 3( Network Layer). These switches referred to as Layer 3 switches or multilayered switches.

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Basic Function of a Network Ethernet Switch and a Network Ethernet Hub are same. That is to forward Layer 2 packets (Ethernet frames) from source device to the destination device. But, a Network switch is more intelligence than a hub. Because an Ethernet switch uses MAC addresses to make forwarding decisions. It does not know about the protocol carried in the data portion such as an IPv4 packet. The switch makes its forwarding decisions based only on the Layer 2 Ethernet MAC addresses.
Unlike an Ethernet hub that repeats bits out all ports except the incoming port; an Ethernet switch consults a MAC address table to make a forwarding decision for each frame. The MAC address table is sometimes referred to as a content addressable memory (CAM) table. Network Switches of different input and output bandwidths are available. Today’s Ethernet Network Switches can have bandwidths of 10, 100, 1000 or 10,000 Megabits per second.

Switch Features and Advantages

  • Connect network devices together in a Local Area Network (LAN).
  • Its learn Layer 2 (MAC) addresses and forward Layer 2 packets (Ethernet frames); to exact destination with the help of device mac address
  • It’s control of who has access to various parts of the network.
  • Provision to monitor network usage.
  • High-end switches have pluggable modules.
  • Allow to connect multiple device and port can be managed  VLAN can create security also can applyswitch
  • First broadcast; then unicast & multicast as needed.
  • Switches use content accessible memory CAM table which is typically accessed by ASIC (Application Specific integrated chips).
  • Half/Full duplex
  • Connecting two or more nodes in the same network or different network
  • The switch has one broadcast domain [unless VLAN implemented]

Router

The router is a network device. It selects the best path for a data packet. The router is located at any gateway (where one network meets another). Its forward data packets from one network to another switchbased on the address of the destination network in the incoming packet and an internal routing table. It also determines which port (line) to send out the packet (ports typically connect to Ethernet cables). Routers also require packets formatted in a routable protocol. The global standard being TCP/IP, or simply switchIP.” Routers operate at Layer 3 (network layer) of the OSI model and it uses the destination IP address in a data packet to determine where to forward the packet. Router store IP address in Routing table and maintain address on its own.