Communicating over the Network Network Fundamentals – Chapter 2 Sandra Coleman, CCNA, CCAI

Objectives 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.

Network Structure Three elements of communication Message source The channel Message destination Data or information networks capable of carrying many different types of communications

How are messages communicated? Data is sent across a network in small “chunks” called segments – known as segmentation Multiplexing – describes the process of interleaving multiple digital data streams into ONE signal (see example in online curriculum 2.1.2) It increases the reliability of network communications Disadvantage is the amount of encapsulation that must occur with every segment, especially for large amounts of data!

Network Components Hardware (includes devices and media) Software (services and processes)

End Devices End devices form interface with human network & communications network Originate data flow! Examples: computers, printers, VoIP Phones, cameras, cell phones, etc. Commonly referred to as hosts (source or destination of a message) Each host has an address that will identify it on the network Role of end devices: Client (software installed so they can request & display info from the server) Server (provide information and services to other hosts) Both client and server

Intermediary Devices Role of an intermediary device Examples: Hubs, switches, access points, routers, modems, firewalls, etc. Provides connectivity and manages data flows across network Works behind the scenes Determines the path data will travel to get from source to destination Knows all the paths that exist Informs other like devices about errors or communication failures Retimes & retransmits signals as necessary

Network Media this is the channel over which a message travels Encoding is different for each type, i.e. electrical impulses, light pulses, wave patterns

Network Types Local Area Networks (LANs) A network serving a home, building or campus is considered a Local Area Network (LAN) Single geographic area, usually a common organization Administered by a single organization Provides network services to a common organization

Network Types Wide Area Networks (WANs) LANs separated by geographic distance are connected by a network known as a Wide Area Network (WAN) Be able to identify a LAN and a WAN given a similar diagram

Network Types Define the Internet The internet is defined as a global mesh of interconnected networks

Network Symbols – be able to recognize

Function of Protocol in Network Communication A protocol is a set of predetermined rules Implemented in software that is loaded on each host and network device View them as a stack – from low to high in a hierarchy Outline the functions necessary to communicate between layers

Network Protocols Network protocols are used to allow devices to communicate successfully Protocols agree on structure of message (specific to PDU’s) Protocols agree on the process of sharing, error handling, and termination procedures – all functions necessary for communication Require layer dependent encapsulations

Protocols and Industry standards A standard is a process or protocol that has been endorsed by the networking industry and ratified by a standards organization Ensures all protocols (open or proprietary) will work together IEEE (Institute of Electrical and Electronic Engineers) IETF (Internet Engineering Task Force)

Function of Protocol in Network Communication Examples of Protocols

Function of Protocol in Network Communication Technology independent Protocols 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

Layers with TCP/IP and OSI Model Benefits of using a layered model Assists in protocol design Fosters competition (different vendors can work together) Changes in one layer do not affect other layers Provides a common language

Layers with TCP/IP and OSI Model Away Pizza Sausage Throw Not Do Programmers Know the layers in order!

Layers with TCP/IP and OSI Model TCP/IP Model – created in early 1970s – KNOW what each layer is responsible for! Open Standard

Layers with TCP/IP and OSI Model Protocol data units (PDU) and encapsulation PDUs are SPECIFIC to each layer! Know PDUs at EACH layer!

Key functions of encapsulation Ensure that data pieces get from sending to receiving device Ability to re-assemble the data packets correctly Ability to identify data packets that belong together with the same communication package

Comparing TCP/IP and OSI Model Know these layers and how they compare between the two models

Addressing and Naming Schemes Explain how labels in encapsulation headers are used to manage communication in data networks

Addressing and Naming Schemes Describe examples of Ethernet MAC Addresses, IP Addresses, and TCP/UDP Port numbers

Addressing and Naming Schemes Think about a computer that has only one network interface on it. All the data streams created by the applications that are running on the PC enter and leave through that one interface, yet instant messages do not popup in the middle of word processor document or e-mail showing up in a game. This is because the individual processes running on the source and destination hosts communicate with each other. Each application or service is represented at Layer 4 by a port number.

Things to do NOW! Demonstrate tracert Demonstrate packet tracer…how to set up a network Map them a drive to Public…

Ch. 2 is Finished! Labs & Skills Integration Lab 2-1 (Do this on PT 2.6.1.2, pg. 48 in lab book- I have the files from the CD loaded on public) Ch. 2 Test will be on Tuesday Sept. 5 or Wed. Sept 6, 2012 Online Test – Must be taken by midnight on Sunday September 2, 2012. I will NOT turn it on again! Homework – due on test day! Study Guide p. 34 – Matching (table 2-1 & 2-2) p. 35-36 – Matching (table 2-3 & 2-4) p. 37-38 – Matching (table 2-5 & 2-6) Packet Tracer Activities in the textbook 2.2.4.2 (pg. 44) 2.4.8.2 (pg. 54)