What is a router and what is a difference betn adsl modem , adsl router,and router?

Question

what is a router , where it is used. is there any difference between adsl modem, adsl router, and router.give me some help on managed switched i.e L1 & L2 swithces.

Answer 1

Wow there are quite a few questions there.

Question 1: What's the difference between a router, ADSL modem, and an ADSL router?

First off, an ADSL modem is nothing more than the device that communicates with the phone company's servers and connects you to the internet.  By the way, ADSL stands for asynchronous DSL.  This is the most common type of DSL.  It just means that your download speed is different than your upload speed.  Synchronous DSL is much more expensive and is therefore reserved for business use.  Anyway, an ADSL modem will allow only one computer to connect to the internet as any given time.

A router is a device that will "split" an internet connection, allowing multiple computers to share the same connection.  Without a router, you would need unique public IP addresses for each computer.  Because this is very expensive and unnecessary, a router is used.  The ISP will generally assign you one dynamic IP address.  The router will assume this address and then is assigns private addresses to all of your other computers.  Routers not only save money, they also help protect your computers by preventing someone from directly accessing them by using your public IP address.  Most also include a firewall.

Now an ADSL router is essentially an ADSL modem + a router all in one unit.  These devices are typically rented or purchased thru the ISP themselves.

Question 2: What are managed switches?

Switches allow you to take one network port and split it into multiple ones.  A managed switch allows you to have greater control over what each port does, security restrictions, etc.  This is typically accomplished by connecting to the switch via a web browser.  An unmanaged switch lacks any customization.  It is also much cheaper.  

All switches will route packets from one port to another port.  Think of a switch as a postal worker delivering mail to its proper address.  This is different from hubs, in that hubs will sends packet thru all its ports, irregardless of where they're supposed to go.  The switch uses information inside the packet and some sort of lookup table to determine who the packet should be sent to and who is connected to what port.  The difference between layers is simply what information is used to route the packets.  This is analogous to the postal worker using your longitude/latitude coordinates versus a standard address.  Below is a table of what each layer represents.  It's available at the website under "sources".

I hope this help;)

          Forwarding

          Decision

Layer  Based on            Examples

2        MAC address      Ethernet, Token Ring, etc.

3        Network address  IP, IPX, etc.

3        Service quality     IP, IPX, etc.

3        Application          IPX socket

4        Application          IP socket

Answer 2

Hey there,

Ofcoarse there's a difference... they all differ than the others : -

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          Wireless Router : -



A wireless router allows for network communication to take place between a computer. ( It allows ya to spread the internet in this area)

  

A wireless router is a network device that routes IP traffic across several wireless IP networks and wired networks. ...

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      Modem: -  

A modem converts the serial digital (binary) data from a transmitting terminal into a form suitable for retransmission over an analog telephone channel. A second modem reconverts this signal to binary data for acceptance by the receiving terminal.

  A device that converts digital data into analog signals and vice-versa for transmission over a telephone line.

Equipment that converts between digital data and audio tones for transmission and reception over analog channels.

A device used that you connect to your computer and phone line to the internet.

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  What is an Adsl Router ?

An ADSL router is also known as a DSL modem. The router is used to connect the computer to the DSL phone line for using the ADSL service. Some countries also use the term NTBBA, which stands for Network Termination BroadBand Access. There are some ADSL routers that are also capable of sharing a single Internet connection with a group of computers on a network. This system is also known as the residential gateway.

I hope every single info help ya. ;-)