Understanding Different Types of Computer Networks and Their Characteristics, Lecture notes of Network Design

Download Understanding Different Types of Computer Networks and Their Characteristics and more Lecture notes Network Design in PDF only on Docsity! Computer Networks Objectives  Types of Networks  3-Layers Network Design Model  Collision Domain vs Broadcast Domain  Carrier Sense Multiple Access with Collision Detection (CSMA/CD)  The Layered Approach Classification of Computer Networks  Computer networks are classified based on various factors. They includes:  Geographical span  Inter-connectivity  Administration  Architecture Network Types  Personal Area Network  Local Area Network  Metropolitan Area Network  Wide Area Network Personal Area Network  personal to a user  connectivity range up to 10 meters  E.g. wireless computer keyboard and mouse, Bluetooth enabled headphones, wireless printers and TV remotes Wide Area Network  covers a wide area which may span across provinces and even a whole country  connectivity to MANs and LANs Comparison LAN  Confined to small areas i.e., it connects several devices over a distance of 5 to 10 km.  High speed.  Most inexpensive equipment.  Low error rates.  Data and hardware sharing between users owned by the user.  Operates at speeds ranging from 10Mbps to 100Mbps. Now days 1000 Mbps are available. MAN  Confined to a larger area than a LAN and can range from 10km to a few 100km in length.  Slower than a LAN but faster than a WAN.  Operates at a speed of 1.5 to 150 Mbps.  Expensive equipment.  Moderate error rates. WAN  A WAN can range from 100km to 1000km and the speed between cities can vary form1.5 Mbps to 2.4 Gbps.  WAN supports large number of computers and multiple host machines.  Various segments of network are interconnected using sophisticated support devices like routers and gateways.  Usually the speed is much slower than LAN speed.  Highest possible error rate compared to LAN & MAN. Concept of hierarchy @e * e ee CQ Ceol Cc fNQ 3 Layers Network Design Model The Core Layer  The core layer is responsible for transporting large amounts of traffic both reliably and quickly.  The only purpose of the network’s core layer is to switch traffic as fast as possible.  Things we don’t want to do:  Never do anything to slow down traffic  Don’t support workgroup access here  Avoid expanding the core  Things that we want to achieve:  Design the core for high reliability  Design with speed in mind  Select routing protocols with lower convergence times Collision Domain vs Broadcast Domain • Ethernet Networks  Ethernet is a contention-based media access method that allows all hosts on a network to share the same link’s bandwidth.  Ethernet is a family of technologies that provides data-link and physical specifications for controlling access to a shared network medium.  Ethernet has several benefits:  Simple to install and manage  Inexpensive  Flexible and scalable  Easy to interoperate between vendors HUB Collision vs. Broadcast Domain Example Collision Domain Domain Remember That!  Routers separate broadcast and collision domains.  Switches separate collision domains.  Hubs belong to only one collision domain.  Switches and hubs both only belong to one broadcast domain. Energy level during transmission, idleness, or collision Energy Collision Frame transmission Frame transmission Time Idle Behavior of three persistence methods for CSMA/CD Sense and transmit Continuously sense Time Busy a. 1-persistent Sense and transmit Time Busy b. Nonpersistent Probability outcome does not allow transmission. Transmit 1 1 ' Continuously sense 1 ' 1 Ti ! Time slot 1 Time slot Time Busy c. p-persistent CSMA/CD  When a collision occurs on an Ethernet LAN, the following happens:  A jam signal (32-bits) informs all devices that a collision occurred.  The collision invokes a random backoff algorithm.  Each device on the Ethernet segment stops transmitting for a short time until its backoff timer expires.  All hosts have equal priority to transmit after the timers have expired. The Layered Approach Layered Tasks An example from the everyday life Hierarchy? Services