Common networking terms
Switch: A switch is used to connect one or more computers.
It is a plug and play device that needs no configuration whatsoever in order to interconnect a number of computers.
You just insert all the LAN cables from all your computers into its sockets and you would already have an established network, given that they are in the same IP range and they have the same subnet. After that, you can then configure each of the computers about what services and folders you would want it to share.
Another switch like device is a hub.
A hub broadcasts data from source to all the connected computers.
So if a connected computer needs to send something while a hub is broadcasting, then it needs to wait. This makes the hubs very slow. Also, as more computers are connected to a hub, waiting period increases thus slowing the system further. In a hub, the destinations decide whether they need the data or not.
So a lot of unnecessary transmission happens and a lot of extra traffic is also generated while using the hub.
A switch on the other hand, makes a bridge between only two computers instead of broadcasting to all connected computers.
So, waiting period is very much reduced as multiple pathways can exist between different computers instead of just one source and multiple targets as in the hub.
Hubs became popular because in earlier days when switches were costly.
But now-a-days switches cost the same as hubs, so hubs are no longer used.
However, the names are used interchangeably calling switches as hubs or vice versa.
A switch can learn the addresses of the computers within the network. It accomplishes this “learning” by looking and recording each of the network computer’s MAC address and port or interface on which a frame was received.
Each learned address is stored with the use of an address table.
Bridge is a switch with just 2 ports: one for incoming and one for outgoing.
Router connects one or more networks.
It only connects networks, but cannot connect to the Internet by a telephone line.
Modem connects a network to the Internet on a telephone line.
It just converts from one protocol to another.
So any threat coming through the line is also passed to the network as such.
Router need not do any conversion between protocols.
It is in the router that we can install a firewall to protect from threats, malware etc.
But for those people whose networks carry a lot of traffic, most routers cannot cope with the amount of data that flows through it. For such cases, a router OS is installed into a computer and that acts as the router and gateway. Using this method allows the administrator a lot more freedom and flexibility in configuring his router and gateway.
DHCP (Dynamic Host Configuration Protocol) server: This is a device/software that assigns IP Addresses to a connection.
IP address can be static or dynamic.
A dynamic IP changes every time you connect to the network. This is a method of freeing up IP addresses when the number of clients that connect the network is greater than what it can usually handle.
DHCP server keeps track of which addresses are free and which ones are being used.
Even though a DHCP server is meant for sending out dynamic IP addresses, it can also be used to assign static ones
A static IP address can be acquired via DHCP when the administrator knows the MAC address of your network card and assigns a specific IP address to that.
After that, you would get that specific IP address every time you connect and it is reserved for you only and nobody can use it. Another method of setting a static IP is to manually set it on your network card.
An advantage of a static IP is that it becomes easier for the DNS service to resolve host name running on a static IP. With a host running on a dynamic IP address, a dynamic DNS service is needed that can update with the new IP address every time you connect.
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