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 achieve 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 helpful to understand switch if somebody understands it then he can easily understand a switch.

It 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

[caption id="attachment_223" align="alignright" width="300"] network hub[/caption]

hub, It will blindly copy that data out the interfaces 2 through 5.

It's a common connection point for devices in a network. It is commonly used to connect segments of a LAN. 

It was a cheap and quick way to link up multiple computers in early days.  The main issue with hubs though is that only one computer can talk at a time.  If two computers talked at the same time, their traffic would get combined 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 single broadcast and single collision domain.

Switch

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

switched network

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 destination device. But a Network switch is more intelligence than a hub. Because an Ethernet switch uses MAC addresses to make forwarding decisions. It is completely unaware of the protocol being carried in the data portion of the frame; 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 apply


• 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

A router is defined as a device that selects the best path for a data packet. It is located at any gateway (where one network meets another) further It is a part of a network switch.

Its forward data packets from one network to another based on the address of the destination network in the incoming packet and an internal routing table. It’s 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 “IP.” 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.