(LAN/WAN/MAN fundamentals)

Network Classifications and topologies:

Networks are classified according to the area they are covering. For instance the smallest network consists of two nodes connected to each other. The largest networks could be hundreds or thousands of nodes connected to another.

LAN: A LAN or Local Area Network would consist of a few computers, the best way to think about what a LAN is, would be everything behind the router that gets a private IP address (10.or 192.). A segment is a portion of the LAN where nodes are connected directly. LAN's can have multiple segments tied together.

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MAN: A MAN or Metropolitan Area Network is a network that crosses cites. MAN's uses public connections to get information from one area to the next over the city like T1 or T3. They also use switched services like Integrated Service Digital Network (ISDN), frame relay, Asynchronous transfer mode (ATM), or wireless services. 


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WAN: A WAN or Wide Area Network would be across a region or the world. For instance from city to city or country to country. Information travels only on a WAN when it needs to leave the city for another.

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( NETWORK TOPOLOGY )
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- BUS TOPOLOGY -

This happens to be a single electrical circuit to which all devices in a network are connected. This may be a bunch of different little connections and wires. A bus topology is a broadcast network, meaning when a computer or node transmits data, the signal travels down the bus in both directions and every node or computer connected to the bus will receive the signal. If the signal is not meant for the node or computer it simply ignores it.

Once a signal is at the end of the bus there is a terminator at the end which prevents it from reflecting back. If the bus cable breaks, this means all nodes or computers end up with a loss of internet unless redundant network is in place.                                                                   

 

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- STAR TOPOLOGY -

Having a star topology is the most common topology. Using a central unit such as a switch or hub to communication data, this also is a broadcast network. This is a little different however, for instance if a hub is used then everyone attached to the hub hears everything transmitted.

 If this is switch then it will transfer the packet to the correct port, but is still susceptible to broadcast traffic. If the central unit is down, then again all nodes or computers is going to be down as well.

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 - Ring Topology -

A true to the heard ring technology is many point to point links arranged in a ring fashion. Each of the nodes or computers network interface cards (NIC) has one input and one output connection, so therefore is connected to two links.

When an input connection receives a signal, it re-transmits the signal without buffering to its output connection. This makes it so the flow of data is only in one direction, if the data makes it to a node that it is intended for, the node copies the data and keeps it as it travels down the line, if not, it will simply re-transmit.

The ring will be shut down if any lines are broken, this will not come back up until the wire or node is replaced. Some Fiber Distributed Data Interface (FDDI) have a back up line called duel ring structure to prevent down time and ensure redundancy. Ring topologies are often used as network backbones, this can often connect multiple business floors or even a campus network or a MAN. 

- Star Ring Topology -

As you may of guessed it, a star ring topology combines the star and the ring technology. It combines the physical star configurations with a logical of ring information flow. The star ring topology wires run from each node to a central ring wiring concentrator, this is also often called a multi-station access unit (MAU). 

This creates a physical star topology but travels in a ring logically so it has the ability to see a down node and keep the circuit up.

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- Mesh Topology -

This mesh topology, point to point links directly connect every site to every other site. Mesh networks are usually built over tome as new sites sometimes are added or subtracted from the overall network. The mesh network topology is often used for MAN or WAN networks.

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My information was backed up by the 8th edition of the introduction to Local Area Networks from WestNet Learning.