Network Infrastructure Devices - Hubs, Network Bridge, Network Switch & Router


What is hubs?

Hubs were the common network infrastructure devices used for Local Area Network (LAN) connectivity but network switches are rapidly replacing hubs. These days it is very difficult to spot a Network Hub functioning in a live Local Area Network (LAN). Hubs function as the central connection point for Local Area Network (LAN).

Hubs are designed to work with Twisted pair cabling and normally use RJ45 jack to connect the devices. Network devices (Servers, Workstations, Printers, Scanners etc) are attached to the hub by individual network cables. Hubs usually come in different shapes and different numbers of ports.
When a hub receives a packet of data (an Ethernet frame) at one of its ports from a network device, it transmits (repeats) the packet to all of its ports to all of the other network devices. If two network devices on the same network try to send packets at the same time a collision is said to occur.
Hubs are considered to operate at Physical Layer (Layer 1) of OSI model.

What is a network Bridge, What is a network Switch?

A Bridge/Switch is a network device that typically operates at the Data Link layer (Layer 2) of the OSI model. A bridge or switch performs the its job by examining the Data Link Layer (Layer 2) data packet (Ethernet Frame) and forwarding the packet to other devices based on Layer 2 addresses (MAC Addresses). Both switches and bridges function using Data Link Layer (Layer 2) addressing system, also known as MAC addresses.

Each port of a network switch is in a separate collision domain and therefore Switches are used to divide a big collision domain into multiple smaller collision domains.
Bridge has only few ports and connect only a few collision domains, or Hosts. A Bridge has comparatively less ports than a Switch. A Switch has usually 24 ports or 48 ports. Brides and Switches are considered to operate at the Data Link Layer (Layer 2) of the OSI model. Click the following link to learn the exact differences between Bridges and Switches.

What is a Router? What is a Router, Functions of a router?

A router is another network infrastructure device that directs packets through the network based on information from Network Layer (Layer 3) of OSI model. A router uses a combination of hardware and software to route data from its source to its destination.

A router can be configured to route data packets from different network protocols, like TCP/IP (industry standard), IPX/SPX, and AppleTalk. Routers segment large networks into logical segments called subnets. The division of the network is based on the Layer 3 addressing system, like IP addresses.

If the Network Layer (Layer 3) Data packet (IP Datagram) is addressed to another device on the local subnet, the packet does not cross the router and create a traffic congestion problem in another network. If data is addressed to a computer outside the subnet, the router forwards the data to the addressed network. Thus routing of network data helps conserve network bandwidth. The following picture shows a Cisco 2800 Series Router.

Thanks for reading...

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1 comment:

  1. I have read your article, it is very informative and helpful for me.I admire the valuable information you offer in your articles. Thanks for posting it..
    Network Cables


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