chapter 2 vn.2
DESCRIPTION
dTRANSCRIPT
Chapter 2 1
Topologies
Chapter 2
Chapter 2 2
Chapter Objectives
Explain the different topologies Explain the structure of various topologies Compare different topologies
Chapter 2 3
Recall
LAN types are Ethernet, Token Ring, Token bus and Fiber Distributed Data Interface (FDDI).
OSI layers are Physical, Data Link, Network, Transport, Session, Presentation and Application layer
The factors of network selection criteria are Performance, Reliability and Security
Standards organization is unit which develops, maintains, improves, amends and revises standards
Chapter 2 4
Introducing Topologies
Topology refers to physical or logical arrangement of network
Physical topologies are Single Node Bus Star Ring Mesh Tree Hybrid
Chapter 2 5
Single Node Topology - I
Single device, at times device called dumb terminal is connected to the server
Devices operates on files from server and returns them back after completing task
Chapter 2 6
Single Node Topology - II Advantages:
Easy to install, configure and manage
Least expensive
Single cable is required
Disadvantages:
Network consists of single device
Dumb terminal is dependent on server
Chapter 2 7
Bus topology - I
All devices are connected to a common cable called trunk
Maximum segment length of cable is 200 m Maximum of 30 devices per segment
Chapter 2 8
Bus topology - II
Server is at one end and devices are at different positions
50 ohm terminator is used Devices are not responsible for data transmission Number of collisions are more Daisy chain method can be used to add more
devices
Chapter 2 9
Bus topology - III
Advantages:
Installation of devices is easy
Requires less cable compared to star topology
Less expensive and works better for smaller networks
Disadvantages:
If backbone breaks, entire network gets down
Difficult to isolate problems
Limited number of devices
Chapter 2 10
Star Topology - I Each device is connected to a central device called
hub through cable Data passes through hub before reaching
destination
Chapter 2 11
Star Topology - II
Advantages:
Easy to install, configure, manage and expand
Centralized management
Addition or removal of device does not affect the whole network
Disadvantages:
Requires more cable
Failure of hub affects entire network
More Expensive
Chapter 2 12
Case Study 1
Hyderabad branch of the MoneyMaker bank has built an insurance department in such a way that each device is connected to one another. This department consists of seven agents. It is required that agents should handle only their specific clients since the information is confidential. But in the existing topology the data is not secured. So, Smith, the network administrator, wants to switch over to other topology.
Chapter 2 13
Problem
Design a new type of network for this department.
Chapter 2 14
Suggested Solution
The current topology implemented by the bank is mesh in which information is shared between different devices. To obtain security of data star network seems to be the best choice. It also provides ease of troubleshooting, centralized management and ease of reconfiguration.
Chapter 2 15
Ring Topology - I
Devices are connected in a closed loop
All devices have equal access to media
Device waits for its turn to transmit
Most common type is Token Ring
Chapter 2 16
Ring Topology - II
Advantages:
Data travels at greater speed
No collisions
Handles large volume of traffic
Disadvantages:
More cabling is required compared to bus
One faulty device affects the entire network
Addition of devices affect network
Chapter 2 17
Dual Ring Topology
Consists of two independent primary and secondary rings
Secondary ring is redundant, used only when primary stops functioning
Chapter 2 18
Mesh Topology - I
Used in WANs to interconnect LANs
Every device is connected to every other device
Use routers to determine the best path of communication
Chapter 2 19
Mesh Topology - II
Types
Full mesh Partial mesh
Full mesh topology – All devices are connected to each other
Partial mesh topology - Some devices are connected to only those with whom they exchange most of the data
Chapter 2 20
Mesh Topology - III
Advantages:
Improves fault tolerance
Failure of one link does not affect entire network
Centralized management is not required
Disadvantages:
Difficult to install and manage
Each link from one device to other requires individual NIC
Very much expensive
Chapter 2 21
Tree Topology - I
Connects groups of star networks
Devices are wired to root hub
Root hub is connected to second level devices
Lowest level devices are smaller computers
Chapter 2 22
Tree Topology - II
Advantages: Easy to add new
devices Point-to-point wiring for
each device Fault detection is easy
Disadvantages: Difficult to configure If backbone breaks,
entire network goes down
More expensive
Chapter 2 23
Hybrid Topology - I
Combines two or more different physical topologies Commonly Star-Bus or Star-Ring Star-Ring uses Multistation Access Unit (MAU)
Chapter 2 24
Hybrid Topology - II
Advantages:
Used for creating larger networks
Handles large volume of traffic
Fault detection is easy
Disadvantages:
Installation and configuration is difficult
More expensive than other topologies
More cabling is required
Chapter 2 25
Case Study 2
MoneyMaker Bank at Mumbai has implemented a star topology in their IT department. All computers are connected to the central switch. In the Loan department, all computers are connected in closed loop format. Network administrator, John wants to connect these two networks so that data can be shared among different departments.
Chapter 2 26
Problem
Connect two different departments
Chapter 2 27
Suggested Solution
The administrator can join these two star and ring networks to form a hybrid network with the help of Multistation Access Unit (MAU). It is a centralized hub. Ensure that there is no break in the link between two computers in a ring network and switch in star network is working properly.
Chapter 2 28
Summary - I
Network is an interconnection of many communicating entities that are connected for the purpose of data communication
Topology describes the way in which networking devices are connected to each other
Physical topologies are how the wires are interconnected, while logical topology is how the network behaves and interoperates
Different types of topologies are Single Node, Star, Bus, Ring, Mesh, Tree and Hybrid
Chapter 2 29
Summary - II
In a single node topology, just a single device called dumb terminal is connected to the server
Bus topology connects each device to a single cable and at either end of the cable terminator is used to remove unsent data from the cable
In star topology, multiple devices are connected to a central connection point known as hub or switch
In a ring topology, data travels around the loop in one direction and passes through each device
Chapter 2 30
Summary - III
In a mesh topology, every device is connected to each and every node in the network with many redundant interconnections at least two paths to and from every node
Tree topology connects multiple star networks to other star networks using bus topology
Hybrid topology is a combination of different topologies such as Star-Bus or Star-Ring