A network topologi defines how computer and Other device are connected. A network topology describes the layout of the wire
And device as well as the path used by data transmissions.
Kind of physical topology that are commonly used are now:
- Bus
- ring
- hierarchical
- Star
- extended star
- mesh
Bus topology
Bus topology connects all the devices using a single cable.
This cable proceeds from the computer to the next like a bus line
going thourgh a city.
with bus topology,the main cable segment must end with a
terminator that absorb thi signal when it reaches the end of the line
or ware. Bus topologies were common in the early days of LANs
That used single coaxial cable.
Ring topology
The ring topology is another important topology in Lan
connectivity. Unlike the physical bus topology,the ring topology
has no beginning or the end that needs to be terminated.
a frame travels around the ring,stoping at each node. If a node
wants to transmit data,it is permitted to add that data as well
as the destination address to the frame.
Then continues around the
Ring until it finds the destinations node, which takes data out of
the frame.
Two type of ring topology :
Single ring = in a single ring,all the device on the network
Shere a single cable,and the data travels in one direction only.
Dual ring = two ring allow data to be sent in both directions,
If both ring fail, a WRAP at the fault can heal the topology back
Into a ring.
Star and Extended Star Topology
The star topology, is the most commonly used physical topology in
Ethernet LANs. the star topology is made up of a central
connections poin that is a device such as a HUB,SWITCH,or
ROUTER, where all the cabling segment meet. the network is
Connected to the central device with its own cable.
while Extended Star Topology is when a star network is expanded
to include an additional networking device that is connected to the
main networking device.
( Star topologies and Expanded-star
become more apparent in later chapters when switch and routers
are discussed in more detail).
Hierarchical Topology
a hierarchical topology is created similary to an extended star
topology. The primary difference is that it does not use a central
mode.
Mesh Topology
Two types of the mesh topology :
Full mesh topologies, connects all device to each other for
redundacy and fault tolerance. The wiring in a Full Mesh topology
has very distinct advantages and disadvantages.
Implementing a full mesh topology is expensive and difficult. And
the mash topology is ussualy inplemented in WANs between
router.
Figure.full Mesh topologies
In partial mesh topology,at least one device maintains multiple connections to other with out being full mested. The partial mesh topology is used for many telecommunications backbone,as well internet
