2007 Cisco Systems, Inc. All rights reserved. Cisco Public Objectives Communicating over the Network Network Fundamentals Chapter 2 Chapter 1 1 Describe the structure of a network, including the devices and media that are necessary for successful communications. Explain the function of protocols in network communications. Explain the advantages of using a layered model to describe network functionality. Describe the role of each layer in two recognized network models: The TCP/IP model and the OSI model. Describe the importance of addressing and naming schemes in network communications. 2 2 Network Multiple computers connected together via a communications system Data is sent across a network in small chunks called segments Enables multiplexing interleaving many conversations together over a single link 3 common elements of communication message source the channel message destination 3 3 4 4 Network components hardware the physical components software programs, operating systems, etc. End Devices Computers (work stations, laptops, file servers, web servers) Network printers VoIP phones Security cameras Mobile handheld devices 5 5 6 6
Intermediary Devices Role of an Intermediary Device Provides connectivity for End Devices and ensures data flows across the network Network Access Devices (Hubs, switches, and wireless access points) Internetworking Devices (routers) Communication Servers and Modems Security Devices (firewalls) Network Media The Network Media connects the devices together and provides a path over which the signals can travel Copper cables UTP, coaxial cable. Electrical signals Optical fibre cable. Laser signals. Wireless media. Electro-magnetic signals. 7 7 8 8 Local Area Networks (LANs) A network serving a home, building or campus is considered a Local Area Network (LAN) Covers a limited area, owned by a single organization Wide Area Networks (WANs) LANs separated by geographic distance are connected by a network known as a Wide Area Network (WAN) Organizations usually lease WAN services from a Service Provider 9 9 10 10 Internets and Intranets Data Network Symbols An internetwork is a connection of individual networks, sometimes abbreviated to internet The Internet is a global mesh of public networks An intranet is a collection of interconnected private networks owned by one organization and only accessible to its employees 11 11 12 12
Function of Protocol in Network Communication Technology Independent Protocols A protocol is a set of predetermined rules Network protocols are used to enable devices to communicate successfully A protocol suite is a set of protocols designed to work together, e.g. TCP/IP Industry standard a process or protocol that has been endorsed by the networking industry and ratified by a standards organization 13 13 Many diverse types of devices can communicate using the same sets of protocols. This is because protocols specify network functionality, not the underlying technology to support this functionality. 14 14 The Interaction of Protocols When accessing a Web server, you are using a number of different protocols Layered Network Models Using a layered model helps in the design of complex multi-use, multi-vendor networks Benefits include assists in protocol design fosters competition between vendors changes in one layer do not affect other layers provides a common language There are two important models ISO Reference Model a seven-layered model TCP/IP Protocol Model a four layered model 15 15 16 16 Layers with TCP/IP and OSI Model The TCP/IP Model A protocol model provides a model that closely matches the structure of a particular protocol suite. A reference model provides a common reference for maintaining consistency within all types of network protocols and services. 17 17 18 18
The Communication Process Creation of data at the application layer of the originating source end device Segmentation and encapsulation of data as it passes down the protocol stack in the source end device Generation of the data onto the media at the network access layer of the stack Protocol data units (PDU) and Encapsulation 19 19 20 20 Protocol data units (PDU) and Encapsulation The OSI Model 21 21 22 22 Comparison of TCP/IP and OSI Models Encapsulation Headers Each PDU header contains information about the Source and Destination Transport Port number Network Host machine IP address Datalink Ethernet MAC address 23 23 24 24
Addressing and Naming Schemes Addressing Schemes Ethernet MAC Addresses, IP Addresses, and TCP/UDP Port numbers 25 25 Transport Port number 80 Network IP address 209.165.202.130 Datalink MAC address 00-0C-76-6D-7E-AF 26 26 Port Numbers Summary 27 27 28 28