CCNA ITN Chapter 3-F (PDF)

Chapter 3: Network Protocols and Communication Chapter 3 - Sections & Objectives  3.1 Rules of Communication Explain how rules facilitate communication. Describe the types of rules that are necessary to successfully communicate.  3.2 Network Protocols and Sta...

Chapter 3: Network Protocols and Communication Chapter 3 - Sections & Objectives  3.1 Rules of Communication Explain how rules facilitate communication. Describe the types of rules that are necessary to successfully communicate.  3.2 Network Protocols and Standards Explain the role of protocols and standards organizations in facilitating interoperability in network communications. Explain why protocols are necessary in network communication. Explain the purpose of adhering to a protocol suite. Explain the role of standards organizations in establishing protocols for network interoperability. Explain how the TCP/IP model and the OSI model are used to facilitate standardization in the communication process.  3.3 Data Transfer in the Network Explain how devices on a LAN access resources in a small to medium-sized business network. Explain how data encapsulation allows data to be transported across the network. Explain how local hosts access local resources on a network. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 2 3.1 Rules of Communication © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 3 The Rules Communication Fundamentals  All communication methods have three elements in common: Source or sender Destination or receiver Channel or media  Rules or protocols govern all methods of communication. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 4 The Rules Rule Establishment  Protocols are necessary for effective communication and include: An identified sender and receiver Common language and grammar Speed and timing of delivery Confirmation or acknowledgment requirements  Protocols used in network communications also define: Message encoding ( process of converting information into another acceptable form, for transmission) Message delivery options ( Unicast, Multicast, Broadcast) Message Formatting and Encapsulation (identifying the sender and the receiver) Message Timing ( Access Method, Flow Control..) Message Size ( size restrictions require the source to break a long message into individual pieces) © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 5 The Rules Message Encoding  Encoding between hosts must be in appropriate format for the medium.  Messages are first converted into bits by the sending host.  Each bit is encoded into a pattern of sounds, light waves, or electrical impulses depending on the network media  The destination host receives and decodes the signals in order to interpret the message. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 6 The Rules Message Formatting and Encapsulation  There is an agreed format for letters and addressing letters which is required for proper delivery.  Putting the letter into the addressed envelope is called encapsulation.  Each computer message is encapsulated in a specific format, called a frame, before it is sent over the network.  A frame acts like an envelope providing destination address and source address. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 7 The Rules Message Size  Humans break long messages into smaller parts or sentences.  Long messages must also be broken into smaller pieces to travel across a network. Each piece is sent in a separate frame. Each frame has its own addressing information. A receiving host will reconstruct multiple frames into the original message. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 8 The Rules Message Timing  Access Method Hosts on a network need to know when to begin sending messages and how to respond when collisions occur.  Flow Control Source and destination hosts use flow control to negotiate correct timing to avoid overwhelming the destination and ensure information is received.  Response Timeout Hosts on the network have rules that specify how long to wait for responses and what action to take if a response timeout occurs. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 9 The Rules Message Delivery Options Unicast Message Multicast Message Broadcast Message One-to-one delivery One-to-many delivery One-to-all delivery © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 10 3.2 Network Protocols and Standards © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 11 Protocols Rules that Govern Communications  Protocol suites are implemented by hosts and networking devices in software, hardware or both.  The protocols are viewed in terms of layers, with each higher level service depending on the functionality defined by the protocols shown in the lower levels. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 12 Protocols Network Protocols  Networking protocols define a common format and set of rules for exchanging messages between devices.  Some common networking protocols are Hypertext Transfer Protocol (HTTP), Transmission Control Protocol (TCP), and Internet Protocol (IP). © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 13 Protocols Protocol Interaction  Communication between a web server and web client is an example of an interaction between several protocols: HTTP - an application protocol that governs the way a web server and a web client interact. TCP - transport protocol that manages the individual conversations. IP – encapsulates the TCP segments into packets, assigns addresses, and delivers to the destination host. Ethernet - allows communication over a data link and the physical transmission of data on the network media. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 14 Protocol Suites TCP/IP Protocol Suite © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 15 Protocol Suites TCP/IP Communication Process  When sending data from a web server to a client the encapsulation procedure would be as follows: The webserver prepares the Hypertext Markup Language (HTML) page. The HTTP application layer protocol sends the data to the transport layer. The transport layer breaks the data into segments and identifies each. Next the IP source and destination This frame is delivered to the nearest addresses are added, creating an IP Packet. router along the path towards the web The Ethernet information is then added client. Each router adds new data link creating the Ethernet Frame, or data link information before forwarding the packet. frame. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 16 Protocol Suites TCP/IP Communication Process (Cont.)  When receiving the data link frames from the web server, the client processes and removes each protocol header in the opposite order it was added: First the Ethernet header is removed Then the IP header Then the Transport layer header Finally the HTTP information is processed and sent to the client’s web browser © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 17 Standards Organizations Open Standards  Open standards encourage interoperability, competition, and innovation.  Standards organizations are usually vendor-neutral, non-profit organizations established to develop and promote the concept of open standards. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 18 Standards Organizations Internet Standards  Internet Society (ISOC) –promotes open  Internet Corporation for Assigned Names development and evolution of Internet use and Numbers (ICANN) - coordinates IP globally. address allocation and management of domain names.  Internet Architecture Board (IAB) - management and development of Internet  Internet Assigned Numbers Authority standards. (IANA) - manages IP address allocation, domain name management, and protocol  Internet Engineering Task Force (IETF) - identifiers for ICANN. develops, updates, and maintains Internet and TCP/IP technologies.  Internet Research Task Force (IRTF) - focused on long-term research related to Internet and TCP/IP protocols. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 19 Standards Organizations Electronics and Communications Standard Organizations  Institute of Electrical and Electronics Engineers (IEEE) - dedicated to advancing technological innovation and creating standards in a wide area of industries including networking.  Electronic Industries Alliance (EIA) - standards related to electrical wiring, connectors, and network racks.  Telecommunications Industry Association (TIA) standards for radio equipment, cellular towers, Voice over IP (VoIP) devices, and satellite communications.  International Telecommunications Union- Telecommunication Standardization Sector (ITU-T) standards for video compression, Internet Protocol Television (IPTV), and broadband communications. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 20 Reference Models The Benefits of Using a Layered Model  The benefits of using a layered model include: Assisting in protocol design since protocols at each layer have defined functions. Fostering competition because products from different vendors can work together. Preventing technology changes in one layer from affecting other layers. Providing a common language to describe networking functions and capabilities. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 21 Reference Models The OSI Reference Model  Application - contains protocols used for process-to-process communications.  Presentation - provides for common representation of the data.  Session - provides services to the presentation layer to organize its dialogue and to manage data exchange.  Transport - defines services to segment, transfer, and reassemble the data.  Network - provides services to exchange the individual pieces of data over the network between identified end devices.  Data Link - provides methods for exchanging data frames between devices over a common media.  Physical - describes the mechanical, electrical, functional, and procedural means to transmit bits across physical connections. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 22 Reference Models The TCP/IP Protocol Model  The TCP/IP Protocol Model Created in the early 1970s for internetwork communications. Open Standard. Also called The TCP/IP Model or the Internet Model. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 23 Reference Models OSI Model and TCP/IP Model Comparison  In the OSI model, the network access layer and the application layer of the TCP/IP model are further divided to describe discrete functions that must occur at these layers. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 24 3.3 Data Transfer in the Network © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 25 Data Encapsulation Message Segmentation  Large streams of data are divided into smaller, more manageable pieces to send over the network. By sending smaller pieces, many different conversations can be interleaved on the network, called multiplexing. Each piece must be labeled. If part of the message fails to make it to the destination, only the missing pieces need to be retransmitted. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 26 Data Encapsulation Protocol Data Units  As application data is passed down the protocol stack, information is added at each level. This is known as the encapsulation process.  The form that the data takes at each layer is known as a Protocol Data Unit (PDU). Data - application layer PDU Segment – Transport layer PDU Packet – Network layer PDU Frame – Data Link Layer PDU Bits – Physical Layer PDU © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 27 Data Encapsulation Encapsulation Example  The encapsulation process works from top to bottom: Data is divided into segments. The TCP segment is encapsulated in the IP Packet. The IP packet is encapsulated in the Ethernet Frame. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 28 Data Encapsulation De-encapsulation  The de-encapsulation process works from bottom to top.  De-encapsulation is the process used by a receiving device to remove one or more of the protocol headers. The data is de-encapsulated as it moves up the stack toward the end- user application. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 29 Data Access Network Addresses  Network layer source and destination addresses - Responsible for delivering the IP packet from the original source to the final destination. Source IP address - The IP address of the sending device, the original source of the packet. Destination IP address - The IP address of the receiving device, the final destination of the packet. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 30 Data Access Data Link Addresses  The purpose of the data link address is to deliver the data link frame from one network interface to another network interface on the same network. As the IP packet travels from source to destination it is encapsulated in a new data link frame when it is forwarded by each router. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 31 Data Access Devices on the Same Network  The network layer addresses, or IP addresses, indicate the original source and final destination. Network portion – The left-most part of the address indicates which network the IP address is a member of. Host portion – The remaining part of the address identifies a specific device on the network.  The data link frame which uses MAC addressing, is sent directly to the receiving device. Source MAC address - address of sending device. Destination MAC address – address of receiving device. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 32 Data Access Devices on a Remote Network  Sending to a remote network - the source and destination IP addresses represent hosts on different networks.  The data link frame cannot be sent directly to the remote destination host. Therefore the frame is sent to the default gateway (nearest router interface).  The router removes the received Layer 2 information and adds new data link information before forwarding out the exit interface. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 33 Conclusion Chapter 3: Network Protocols and Communications  Explain how rules facilitate communication.  Explain the role of protocols and standards organizations in facilitating interoperability in network communications.  Explain how devices on a LAN access resources in a small to medium- sized business network. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 34