1. CCNA1-1 Chapter 2 Communicating Over the Network

2. CCNA1-2 Chapter 2 Elements of Communication People communicate in many different ways. People communicate in many different ways. Vocal, a look, a hand signal, …Vocal, a look, a hand signal, … All of the methods have three things in common. All of the methods have three things in common. There is source for the message or a sender.There is source for the message or a sender. There is a destination for the message or a receiver.There is a destination for the message or a receiver. There is a channel that consists of the media that provides the pathway for the message.There is a channel that consists of the media that provides the pathway for the message.

3. CCNA1-3 Chapter 2 Elements of Communication Devices communicate in exactly the same way. Devices communicate in exactly the same way.

4. CCNA1-4 Chapter 2 Communicating the Messages In theory, a network communication could be sent as one continuous stream of 1’s and 0’s. In theory, a network communication could be sent as one continuous stream of 1’s and 0’s. No other device would be able to send or receive messages on the same network. No other device would be able to send or receive messages on the same network. Significant delaysSignificant delays Inefficient use of the channelInefficient use of the channel Any lost, message entirely retransmitted.Any lost, message entirely retransmitted.

5. CCNA1-5 Chapter 2 Communicating the Messages A better approach is called Segmentation. A better approach is called Segmentation. The data stream is divided into smaller, more manageable segments. The data stream is divided into smaller, more manageable segments. Segmentation has two benefits: Segmentation has two benefits: Multiplexing:Multiplexing: Different transmissions can be interleaved on the network.Different transmissions can be interleaved on the network. ReliabilityReliability

6. CCNA1-6 Chapter 2 Interconnections Over time, 2 different techniques have been developed for multiplexing Over time, 2 different techniques have been developed for multiplexing "circuit switching" : used by telephone network"circuit switching" : used by telephone network "packet switching" : used by the internet"packet switching" : used by the internet

7. CCNA1-7 Chapter 2 Interconnections The transmission of information in circuit-switching networks occurs in two phases The transmission of information in circuit-switching networks occurs in two phases Setup phase : a path is allocated from source to destinationSetup phase : a path is allocated from source to destination Information transfer phase : the frames are actually sentInformation transfer phase : the frames are actually sent

8. CCNA1-8 Chapter 2 Interconnections Our objective: to allow for any sender to transmit data at any time WHILE allowing the link to be shared Our objective: to allow for any sender to transmit data at any time WHILE allowing the link to be shared Solution : Packet switching Solution : Packet switching Uses a tantalizingly simple idea: adding to each frame of data a little bit of information that tells the switch HOW to forward it => this is what we call headerUses a tantalizingly simple idea: adding to each frame of data a little bit of information that tells the switch HOW to forward it => this is what we call header

9. CCNA1-9 Chapter 2 Communicating the Messages Segmentation and Reliability: Segmentation and Reliability: Increases the reliability of network communications.Increases the reliability of network communications. Separate pieces of each message can travel across different paths to destination.Separate pieces of each message can travel across different paths to destination. Path fails or congested, alternate path can be used.Path fails or congested, alternate path can be used. Part of the message fails to make it to the destination, only the missing parts need to be retransmitted.Part of the message fails to make it to the destination, only the missing parts need to be retransmitted. In a packet switched network like the Internet.

10. CCNA1-10 Chapter 2 Communicating the Messages Segmentation Disadvantage: Added level of complexity. Segmentation Disadvantage: Added level of complexity. The label is a unique sequence number.The label is a unique sequence number.

11. CCNA1-11 Chapter 2 Components of the Network

12. CCNA1-12 Chapter 2 End Devices Work Stations, Servers, Laptops, Printers, VoIP Phones, Security Cameras,... Work Stations, Servers, Laptops, Printers, VoIP Phones, Security Cameras,... Any device that allows us to interface with the network. Any device that allows us to interface with the network. End devices are referred to as hosts and are either the source or destination of a message. End devices are referred to as hosts and are either the source or destination of a message.

13. CCNA1-13 Chapter 2 End Devices End Devices: End Devices: A host can be a client, a server or both.A host can be a client, a server or both. The software installed on the device determines its role.The software installed on the device determines its role. Servers: Servers: Software that enables them to provide information and services (E-mail, Web Pages) to other hosts on the network.Software that enables them to provide information and services (E-mail, Web Pages) to other hosts on the network. Client: Client: Software installed that enables them to request and display the information obtained from the server.Software installed that enables them to request and display the information obtained from the server. Servers Clients

14. CCNA1-14 Chapter 2 Intermediary Devices Routers, Switches, Hubs, Wireless Access Points, Security Devices. Routers, Switches, Hubs, Wireless Access Points, Security Devices. Any device that provides connectivity to other networks or links between network segments. Any device that provides connectivity to other networks or links between network segments.

15. CCNA1-15 Chapter 2 Intermediary Devices Manage data as it flows through the network. Manage data as it flows through the network. Some use the destination host address and network interconnection information to find the best path through the network. Some use the destination host address and network interconnection information to find the best path through the network.Routers Access Points Switches Hubs Firewalls

16. CCNA1-16 Chapter 2 Media The medium provides the channel over which the messages travel from source to destination. The medium provides the channel over which the messages travel from source to destination. Metallic wires within cables Glass or plastic fibers Wireless Transmission

17. CCNA1-17 Chapter 2 Communicating Over the Network Protocols

18. CCNA1-18 Chapter 2 Rules That Govern Communications Protocols: Protocols: Are the rules that govern communications.Are the rules that govern communications. The format or structure of the message. How and when error and system messages are passed between devices. The setup and termination of data transfer sessions. The method by which networking devices share information about pathways with other networks.

19. CCNA1-19 Chapter 2 Protocol Suites Protocol Suite: Protocol Suite: A group of inter-related protocols that are necessary to perform a communication function.A group of inter-related protocols that are necessary to perform a communication function. Cannot function without a set of standards that network vendors can follow.Cannot function without a set of standards that network vendors can follow. Institute of Electrical and Electronics Engineers (IEEE):Institute of Electrical and Electronics Engineers (IEEE): Develops standards in telecommunications, information technology and power generation.Develops standards in telecommunications, information technology and power generation. Examples: 802.3 (Ethernet), 802.11 (WLAN)Examples: 802.3 (Ethernet), 802.11 (WLAN) Internet Engineering Task Force (IETF)Internet Engineering Task Force (IETF) Internet standards, RFCs (Request for Comments)Internet standards, RFCs (Request for Comments) Example: TCP, IP, HTTP, FTPExample: TCP, IP, HTTP, FTP

20. CCNA1-20 Chapter 2 20 2. Protocol, service and other fancy definitions Peer entities Peer entities two (or more) instances of the same layertwo (or more) instances of the same layer Protocol and a PDU: Protocol and a PDU: the rules of the operation followed by peer entitiesthe rules of the operation followed by peer entities the data exchanged is called PDU (Protocol Data Unit)the data exchanged is called PDU (Protocol Data Unit) there is one protocol (or more) at every layer Examples of protocols are: TCP; UDP;IP; Ethernet Connection Connection a protocol is connection oriented if the peer entities must be synchronized before exchanging useful data (connection set up); otherwise it is connectionless. The telephone system is connection oriented: before A can send some information to B, A has to call B (or vice versa) and say “hello”. The postal (mail) system is connectionless. If A wants to send some information to B, A can write a letter and mail it, even if B is not ready to read it.a protocol is connection oriented if the peer entities must be synchronized before exchanging useful data (connection set up); otherwise it is connectionless. The telephone system is connection oriented: before A can send some information to B, A has to call B (or vice versa) and say “hello”. The postal (mail) system is connectionless. If A wants to send some information to B, A can write a letter and mail it, even if B is not ready to read it.

21. CCNA1-21 Chapter 2 Interaction of Protocols operation rules between peer entities are called protocol operation rules between peer entities are called protocol Layering of protocol entities is reflected by the term of a protocol stack. Layering of protocol entities is reflected by the term of a protocol stack.

22. CCNA1-22 Chapter 2 Technology Independent Protocols Protocols are not dependent upon any specific technology. Protocols are not dependent upon any specific technology. They describe what must be done to communicate but not how it is to be carried out.They describe what must be done to communicate but not how it is to be carried out.

23. CCNA1-23 Chapter 2 Communicating Over the Network Using Layered Models

24. CCNA1-24 Chapter 2 Layered Models Divide and conquer – make things manageable. Divide and conquer – make things manageable.

25. CCNA1-25 Chapter 2 Protocol and Reference Models Protocol Model: Protocol Model: The TCP/IP model is a protocol model because it describes the functions that occur at each layer of protocols only within the TCP/IP suite.The TCP/IP model is a protocol model because it describes the functions that occur at each layer of protocols only within the TCP/IP suite.

26. CCNA1-26 Chapter 2 Protocol and Reference Models Reference Model: Reference Model: Provides a common reference for maintaining consistency within all types of network protocols and services.Provides a common reference for maintaining consistency within all types of network protocols and services. Not intended to be an implementation specification.Not intended to be an implementation specification. Primary purpose is to aid in clearer understanding of the functions and process involved.Primary purpose is to aid in clearer understanding of the functions and process involved.

27. CCNA1-27 Chapter 2 TCP/IP Model Open Standard Open Standard No one company controls it. No one company controls it. Governed by IETF Working Groups Governed by IETF Working Groups Standards proposed using Request for Comments (RFCs). Standards proposed using Request for Comments (RFCs).

28. CCNA1-28 Chapter 2 Request For Comments RFC

29. CCNA1-29 Chapter 2 The Communication Process Segment and Encapsulate Generate on to the media Create Data Transport through the segment Pass data to application Receive from the media Decapsulate and Reassemble

30. CCNA1-30 Chapter 2 Protocol Data Units and Encapsulation Header HeaderData HeaderTrailer Email Message DataDataData Data Data 0010100111011001010000011111010100010101 Segmentation and Encapsulation

31. CCNA1-31 Chapter 2 Protocol Data Units and Encapsulation Header Header HeaderTrailer Email Message DataDataData Data Data Data Decapsulation and Reassembly Data 0010100111011001010000011111010100010101

32. CCNA1-32 Chapter 2 Protocol Data Units and Encapsulation Header Header HeaderTrailer Email Message Data Data Data Protocol Data Units Data Segment Packet Frame

33. CCNA1-33 Chapter 2 Protocol Data Units and Encapsulation

34. CCNA1-34 Chapter 2 Communicating Over the Network The OSI Model

35. CCNA1-35 Chapter 2 OSI Model The International Organization for Standardization (ISO) released the Open Systems Interconnection (OSI) reference model in 1984. The International Organization for Standardization (ISO) released the Open Systems Interconnection (OSI) reference model in 1984. www.iso.org for more information www.iso.org for more information www.iso.org

36. CCNA1-36 Chapter 2 OSI Model Breaks network communication into smaller, more manageable parts. Breaks network communication into smaller, more manageable parts. Makes learning it easier to understand.Makes learning it easier to understand. Prevents changes in one layer from affecting other layers.Prevents changes in one layer from affecting other layers. Standardizes network components to allow multiple vendor development and support. Standardizes network components to allow multiple vendor development and support. Allows different types of network hardware and software to communicate with each other. Allows different types of network hardware and software to communicate with each other. It is a descriptive scheme. It is a descriptive scheme.

37. CCNA1-37 Chapter 2 OSI Model – Example - FYI Descriptive Scheme: Can be used to describe the functionality and interaction of different protocol suites. Descriptive Scheme: Can be used to describe the functionality and interaction of different protocol suites. TCP/IP Physical Data Link Network Transport Session PresentationApplication LAN / Wan Physical Media ARP / RARP LLC IP ICMP RIP IGMP TCPUDP NETBIOSDNS FTP, Telnet, SMTP, POP3, IMAP4, HTTP, X-Windows SNMP, TFTP, BOOTP, DHCP

38. CCNA1-38 Chapter 2 OSI Model LayersCISCOMICROSOFT 7Application All Away 6Presentation People Pizza 5Session Seem Sausage 4Transport ToToToTo Throw 3Network Need Not 2Data Link Data DoDoDoDo 1Physical Processing Please Usually referenced by layer number These two layers are not commonly referred to in most instances.

39. CCNA1-39 Chapter 2 OSI Model LayersCISCOMICROSOFT 7Application All Away 6Presentation People Pizza 5Session Seem Sausage 4Transport ToToToTo Throw 3Network Need Not 2Data Link Data DoDoDoDo 1Physical Processing Please Primary concern: Communications between applications Primary concern: Moving raw data cross the network

40. CCNA1-40 Chapter 2 Communicating Over the Network Network Addressing

41. CCNA1-41 Chapter 2 OSI Model OSI Model Layer Addressing Application Encoded Application Data (Usually referred to as the Upper Layers) Presentation Session TransportSource and Destination: Process Address NetworkSource and Destination: Logical Network Address Data Link Source and Destination: Device Physical Address PhysicalTiming and Synchronization Bits

42. CCNA1-42 Chapter 2 Getting Data to the End Device Header Header HeaderTrailer Email Message Data Data Data Encoded Data Process Logical Physical Encapsulation Process and Addressing 1. 2. 3. 4. 5. 6. 7. Addressing always includes both the Source and Destination Addresses.

43. CCNA1-43 Chapter 2 Getting Data to the End Device 1. 2. 3. 4. 5. 6. 7. Layer 2 Addressing Delivery on a single local network. Delivery on a single local network. Hop by hop address Hop by hop address Unique on the network and represents the device. Unique on the network and represents the device. Codes placed on the NIC by the manufacturer. Codes placed on the NIC by the manufacturer. Referred to as the physical address or the MAC address. Referred to as the physical address or the MAC address. Header TrailerData Source and Destination Physical or MAC Address

44. CCNA1-44 Chapter 2 Getting Data to the End Device Destination MAC Address Source MAC Address Data Layer 2 Header

45. CCNA1-45 Chapter 2 Getting Data Through The Network HeaderData Source and Destination Logical Network Address (IP) 1. 2. 3. 4. 5. 6. 7. Layer 3 Addressing Move data from one local network to another local network. Move data from one local network to another local network. Addresses must identify both the network and the host on that network. Addresses must identify both the network and the host on that network. Used by routers to determine the best path to the destination host. Used by routers to determine the best path to the destination host.

46. CCNA1-46 Chapter 2 Getting Data Through the Network Destination MAC Address Source MAC Address Destination Logical Address Source Logical Address Data Layer 2 Header Layer 3 Header

47. CCNA1-47 Chapter 2 Getting Data to the Right Application 1. 2. 3. 4. 5. 6. 7. Layer 4 Addressing Identifies the specific process or service running on the destination host that will act on the data. Identifies the specific process or service running on the destination host that will act on the data. Differentiate Multiple, simultaneous applications. Differentiate Multiple, simultaneous applications. HeaderData Process Under TCP/IP, a port number to identify the application. Under TCP/IP, a port number to identify the application. Port 80: HTTP (Web Browser)Port 80: HTTP (Web Browser) Port 25: SMTP (Email)Port 25: SMTP (Email) Port 194: IRC (Internet Relay Chat)Port 194: IRC (Internet Relay Chat)

48. CCNA1-48 Chapter 2 Getting Data to the Right Application Destination MAC Address Source MAC Address Destination Logical Address Source Logical Address Destination Process Address Source Process Address Data Layer 2 Header Layer 3 Header Layer 4 Header

49. CCNA1-49 Chapter 2 Putting It All Together Destination MAC Address Source MAC Address Destination Logical Address Source Logical Address Destination Process Address Source Process Address Data Logical MAC Port MAC

50. CCNA1-50 Chapter 2 Comparing the OSI and TCP/IP Models OSI Model Layer Function Protocol Data Unit Device TCP/IP Model 7ApplicationUser Functionality CharacterApplication 6PresentationCharacter Representation 5SessionManage Data Exchange 4Transport Services to segment, transfer and reassemble the data SegmentTransport 3Network Network addressing and best path determination PacketRouterInternet 2Data Link Methods for reliable frame exchange over a common media FrameSwitch Network Access 1Physical Describe physical characteristics to transmit bits over a common media BitHub

51. CCNA1-51 Chapter 2 Brain a little fuzzy? You need to learn to crawl before you can walk and walk before you can run. You need to learn to crawl before you can walk and walk before you can run. We are starting with the theory and concepts and will move on to the actual design and implementation of networks. We are starting with the theory and concepts and will move on to the actual design and implementation of networks.