lets go deeper in NETWORK! system.
diz week lcture are about NETWORK TOPOLOGY or in a simple way to be clearly see n say is NETWORK STRUCTURE..

Topology can be understood as the shape or structure of a network. This shape does not necessarily correspond to the actual physical design of the devices on the computer network.

NETWORK TOPOLOGY is define as the study of arrangementor mapping of the elements (link, nodes  & etc) of a network especially the physical (real) & logical (virtual) interconnections between nodes.

there are TWO TYPES of NETWORK TOPOLOGY:

1) physical topology
              refers to the physical design of a network including the devices, location and cable installation

*there are 4 major physical topologies:

- linear bus

• all workstations connect to the same
  cable segment
• commonly used for implementing
  Ethernet at 10mbps
• the cable is terminated at each end
• wiring is normally done point to point
• a faulty cable or workstation will take
  the entire LAN down
• two wire, generally implemented using
  coaxial cable during the 1980's

 -star

• workstations/nodes connected directly to a central network hub/concentrator 
• data passes through the hub/concentrator before continuing to its destination.
• HUB= manage & controls all functions of the network also act as repeator 
• faulty workstations can be bypassed 
• easy to add new workstation
• more cabling required & EXPENSIVE than linear bus
• the connectors used tend to cause a lot of problems
• commonly used to implement token ring at 4 and 16mbps
• usually, it is configured with twisted pair cable/coaxial cable/fibre optic cable
  *concentrator-  a concentrator is a device that acts as an efficient forwarder of data transmission signals. A remote access hub is sometimes referred to as a concentrator. The term aggregator is also frequently used with approximately the same meaning. A typical concentrator or remote access hub is a device that handles incoming dial-up calls for an Internet (or other network) poin-of-presence and performs other services. A concentrator or hub may be able to handle up to 100 dial-up modem calls, support a certain number of ISDN connections, and support leased line and frame relay traffic while also functioning as a router.
  
  *repeator-a repeater is an electronic device that receives a signal and retransmit it at a higher level or higher power, or onto the other side of an obstruction, so that the signal can cover longer distances

-star-wired ring 

• combination of two or more star topology features.
  
  

- tree/hybrid topology

• results from the combination of linear bus and star topologies in a single networking system.
• point-to-point wiring for indovodual segments\
• overall length of each segment is limited by the type of cabling used.
• commonly, their basic stucture is LINEAR BUS topology.....if the back bone breaks, the entire segment goes down.
   

2) logical topology @ data tranmission
              refers to how data is actually transferred in a network as opposed to its physical design.