NT1210 Introduction to Networking. Unit 3: Chapter 3, TCP/IP Networks

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1 NT1210 Introduction to Networking Unit 3: Chapter 3, TCP/IP Networks 1

2 Objectives Compare and contrast the OSI and TCP/IP models and their applications to actual networks. Explain the functionality and use of typical network protocols. Analyze network components and their primary functions in a typical data network from both logical and physical perspectives. Differentiate among major types of LAN and WAN technologies and specifications and determine how each is used in a data network. 2

3 Objectives Differentiate between proprietary and nonproprietary protocols. Explain the use of IP addressing in data networks. 3

4 Product Standards and Rules Transmission i Control Protocol (TCP) / Internet t Protocol (IP). Requests for Comment (RFC): Documents created by network stakeholders to comment and improve ideas for standards. Define how products work. Used by network designers. Open source. 4

5 Defining the Rules for a TCP/IP Network Hardware and software work together th to create usable network. Protocols (network software): Hypertext Transfer Protocol (HTTP), Simple Mail Transfer Protocol (SMTP), Post Office Protocol (POP), etc. Used on networked devices (hardware): Phones, game systems, televisions, tablets, computers, software, networking devices, cables, etc. 5

6 Defining the Rules for a TCP/IP Network TCP/IP identifies both stuff and how it works together: th Defines protocols. Defines concepts of Local Area Networks (LANs) and Wide Area Networks (WANs). Defines concept of links and nodes the functions of each. Definition of TCP/IP network: Network built using TCP/IP standards and rules. 6

7 Standards Record details of exactly what new technologies do and how they do it. Help everyone agree to how something works so that it works well within network. Important feature: Documentation of ideas that matter to anyone creating networking products or designing networks. Example: Brief history of Web browsers and servers as envisioned by Web creator Tim Berners-Lee. 7

8 HTTP Example HTTP began life as idea and details of how it was to work had to be determined: What byte values does browser use to send HTTP GET? What byte value does server use to send HTTP REPLY? Is // required before name of server in web address? How does server tell browser when it can t find requested object? How does server tell browser where object s bytes begin and end? 8

9 Hardware Standards d apply to both hardware and software. Example: NICs connectors. Without standards, not all cables would fit NIC s port (proprietary configurations). Fixes size and shape standards for connectors and other networking gear set. 9

10 Hardware Example: This cable has an RJ- 45 connector. (RJ-45 is the name of the standard for the connector). The NIC has an RJ-45 port of the same size. The RJ-45 has 8 pins and looks much like the RJ-11 which is commonly know as a Phone Connector, but is half the size of the RJ-45. Example of Physical Standard: RJ-45 Connector (on Cable) and Socket (on NIC) 10 Figure 3-1

11 Types of Standards, Part 1 National: Standard d approved by a national government which then appoints an organization to oversee it. Example: Electrical power outlets size, shape, electrical current, voltage. International: Standard approved by a group of nations that typically relates to functions that benefit from consistency among the participating nations. Vendor (proprietary): Standard approved by a single vendor which allows the vendor to keep control yet allows other vendors to use them so they are interoperable. 11

12 Types of Standards, Part 2 Vendor Group: Standard d approved by a group of vendors (vendor consortium, vendor alliance, vendor forum). Wants their standards to become national/international standards. Can move quicker than national/international standards groups. Works to get compatible products to market quicker, while working with formal standards groups. De Facto: Standard that exists because it is what is currently in use, usually not written down. Example: MS-Word has become de facto standard of most offices. 12

13 Defining the Rules for a TCP/IP Network Not all protocols and hardware specs are standardized; however, most used today happen to be standards. Networking Standards Compared to Protocols and Hardware Specs 13 Figure 3-2

14 TCP/IP Model Defines large set of standards d implemented together th to create safe and useful network. Model name has many variations but all refer to same idea. TCP/IP network architecture, TCP/IP networking model, TCP/IP networking blueprint. Organizes standards into layers so Humans can understand what networks do. Easier to divide work among different products. Devices can be interoperable. 14

15 TCP/IP Model Commonly-used version of TCP/IP model has five layers. Original TCP/IP model had four layers: Bottom two layers of model combined into Network Interface layer (or Network Access layer). TCP/IP Model 15 Figure 3-3

16 TCP/IP Model Includes standards created for TCP/IP, as well as some created by other standards groups. Each standards-setting ggroup follows some kind of process: Repeated experimentation Documentation Review Comments, etc. Example: Internet Engineering Task Force (IETF) acts as primary standards group for TCP/IP model, so model includes standards created by both IETF and other standards groups. 16

17 Organizations Useful to TCP/IP Sources of Standards in the TCP/IP Model 17 Figure 3-4

18 IETF ( Works as standard-setting d tti group for TCP/IP. Decides: What needs to be updated What new standards need to be added Organized around working groups made up of volunteers who work on new standards (create internet drafts ). Experiments, changes details, improves how new technology works, then shares changes. Submits findings into standards process. Document created by group can become informational or experimental RFC if draft not submitted. 18

19 IETF Working Groups Process Standard and Non-Standard TCP/IP RFCs 19 Figure 3-5

20 IEEE ( Institute t of Electrical l and Electronics Engineers (IEEE). Plays huge role in networking and for TCP/IP in general. World s largest professional organization. IEEE standards for TCP/IP define LANs (including Ethernet, most commonly used wired and wireless LAN technology). Not agency of any particular government or agency. US government appoints ANSI to manage US standards across industries. i ANSI certifies standards by certifying other standards groups. 20

21 ITU International Telecommunications Union. International standards body that focuses on standards for telecom and WAN networking technologies. Example: ITU standards define country codes for international phone calls. Enables worldwide digital voice communications by standardizing voice codecs. TCP/IP model uses ITU standards for same reasons it uses IEEE standards. 21

22 Vendor Consortia & Other Groups Vendor Group/Consortium: Vendors team up to get quick and broad acceptance in marketplace. Group agrees on standardized version of new technology BEFORE formal standards group sets standards. Example: Wi-Fi Alliance ( helped get new wireless technology to market quicker than formal IEEE standards process would have. Tested products to certify (confirm) they worked together. Created pre-standard rules. Allowed vendors to brand products as Wi-Fi certified. Worked with IEEE to help overall standards process. 22

23 Defining the Rules for a TCP/IP Network Overall process: No matter whether a person with good ideas works through the Wi-fi Alliance or IEEE, when those two groups cooperate, products get to market sooner, and the standards happen. Vendor Groups Impact on Speed to Market 23 Figure 3-6

24 LAN/WAN Standards TCP/IP Using Other Standards for LAN and WAN 24 Figure 3-7

Comparing TCP/IP to Other Networking Models:

on one protocol or hardware spec, the TCP/IP model

required to make a complete modern network into one

Each device in the network and each component

25 Comparing TCP/IP to Other Networking Models: Standards While a single standard typically focuses on one protocol or hardware spec, the TCP/IP model collects all the standards needed to do everything required to make a complete modern network into one handy model. Each device in the network and each component follows a subset of the TCP/IP standards, depending on its role. Conceptual View of TCP/IP Model 25 Figure 3-8

26 Comparing TCP/IP to Other Networking Models: History of Networking Models First commercial computers hit market in 1950s and became more common in larger companies by 1960s. Personal computers hit market in late 1970s and became common in 1980s. Networks didn t exist yet. Eventually computer vendors saw need to create network between computers. Individual vendors created their own proprietary networking products and networking models. 26

27 Comparing TCP/IP to Other Networking Models: History of Networking Models Typical enterprise network from the 1980s used 3 different models to operate: IBM networking model. DEC networking model. Other vendor that could connect them together. Typical Mix of Corporate Networks over Three Decades 27 Figure 3-9

28 Comparing TCP/IP to Other Networking Models: History of Networking Models What happened in typical enterprise networks from the 1980s into the early 21 st century? Enter TCP/IP Typical Migration of Enterprise Networks from Vendor Models to TCP/IP 28 Figure 3-10

29 Comparing TCP/IP to Other Networking Models: OSI Model Open Systems Interconnection ti (OSI) model. ISO began work on OSI model following timeline that was close to TCP/IP s: Started in 1970s. Progressed on individual standards in 1980s. Allowed standards-based vendor products to start appearing by early 1990s. The OSI Model 29 Figure 3-11

30 Comparing TCP/IP to Other Networking Models: OSI Model The biggest differences between the TCP/IP and OSI models exist at the top. The TCP/IP model defines many functions as part of the application layer, while the OSI model split those functions into multiple layers. Mapping the Layers of the TCP/IP and OSI Models 30 Figure 3-12

31 Comparing TCP/IP to Other Networking Models: OSI Model Three Example Standards, and the Phrases to Use 31 Figure 3-13

32 Understanding How a TCP/IP Network Works: LANs vs. WANs When defining LANs and WANs, always consider the Data Link and Physical layers as local versus remote or owned versus leased. The Terms LAN and WAN in the TCP/IP Model 32 Figure 3-14

33 Understanding How a TCP/IP Network Works: LAN Physical Links Both the sender and receiver must agree on the rules of how to use the electrical circuit. The sending NIC sends the bits over the loop to create the electrical signal. Signal varies over time to encode different bits. The receiving NIC must know what rules the sender uses so it can interpret the circuit changes into the correct 0s and 1s (bits). NICs on Both Ends of a Cable Creating a Loop 33 Figure 3-15

34 Understanding How a TCP/IP Network Works: LAN Switches Every Ethernet t LAN device connects to the LAN using a cable. The cable installers run a cable from each device to a central place on that floor, usually to a switch that sits in a locked room called a wiring room. By connecting all the cables to the switch, all are connect to the LAN and each other. Using a LAN Switch to Physically Connect Devices to a LAN 34 Figure 3-16

35 Break Take 15 35

36 Data Link Layer The Ethernet t Data Link layer/standards d define the rules (protocols) that t tells the devices how and when to use the Ethernet Physical layer. Using an Address to Send Data to the Right LAN Device 36 Figure 3-17

37 Data Communication over Layers 1 & 2 1. The server sends the data over the physical link, but only after the sever adds the destination MAC (physical) address of to the data. 2. The switch sees the destination address and switches the data to PC1 and PC1 only. 3. The data arrives at PC1, and PC1 knows the data is meant for it because of the MAC address. Using an Address to Send Data to the Right LAN Device 37 Figure 3-17

38 Data Link Layer Many protocols use headers and/or trailers to store bytes of info that control data flow through network. Data Link protocols typically add both header and trailer. Data Link Header and Trailer, Like a Couple of Sticky Notes 38 Figure 3-18

Example: Fred buys house three miles from Barney s house.

39 WANs WAN physical links created by service provider (usually Telco) used by customer company in its corporate network. Example: Fred buys house three miles from Barney s house. Instead of building private road between their houses, Barney and Fred use public road already built. 39

40 WANs WANs create link between sites of corporate network when company could not physically cable between sites itself. Example: Company has two sites 3 miles apart; although Ethernet LAN standards allow for 3-mile-long cables to connect LAN switches at both sites, company can t legally lay cable over other people s land between sites. Solution: Contract with 3 rd party company that has right to run cables near existing roads. Links are leased (rented) from 3 rd party company by customers. 40

Cable TV company has cable lines into most buildings.

41 WAN Examples Telco has phone line into most houses. Electric company has power lines into most buildings. Cable TV company has cable lines into most buildings. Government lets utility companies dig up road to install cables or hang cables from poles above ground. 41

42 Leased Lines Creates equivalent of cable directly between two remote sites. Enterprises lease lines to connect remote sites. Leased lines create 2-way path to transmit data at predetermined speed (for pre-determined price!). 42

43 Leased Lines Enterprises use Layer 3 devices called routers to connect to the WAN leased line at each site. The Telco connects the ends of the leased line directly into the enterprise s routers in their WAN interfaces (ports) on each end of the link. Physical Cabling of a Leased Line, from Each Customer Site to Central Office (CO) 43 Figure 3-21

Leased Lines Two leased lines: One connecting Miami to

The length of the leased line could literally run across

(WAN lines that look like lightning bolts represent leased

44 Leased Lines Two leased lines: One connecting Miami to Atlanta. One connecting Miami to Boston. The length of the leased line could literally run across the street in a city or thousands of miles across a country. (WAN lines that look like lightning bolts represent leased lines.) Leased Line, Cabling View, with Routers Connecting LAN and WAN 44 Figure 3-22

45 Data Link Protocols for Leased Lines High-level Data Link Control (HDLC standardized by ISO). Point-to-Point Protocol (PPP defined by TCP/IP in RFC 1661). Both define address in header to identify devices on physical link When router sends data over leased line, data can only go to router on other end of link. Every Data Link protocol focuses on particular Physical layer technology. Routers typically sit at border between different data links. 45

46 Data Link Protocol Encapsulation Routers strip off old Data Link headers no longer needed d and replace them with new Data Link headers needed for next leg (hop) of the data s journey to its destination. Encapsulation and De-encapsulation 46 Figure 3-23

47 Encapsulation Example 1. Sending device adds Ethernet Data Link header/trailer to data before sending across LAN. 2, 3. Border router removes Ethernet header/trailer and adds new WAN one (e.g., PPP) then sends data over WAN link. 4, 5. Destination border router discards PPP header/ trailer and adds new Ethernet header/trailer for destination device and sends data over LAN. 47

Header/Trailer Encapsulation Example Similar il to steps you take when you take a long trip: 1.Start by taking subway train to airport. 2.Take plane to another city. 3.Rent car at destination. 4.

48 Header/Trailer Encapsulation Example Similar il to steps you take when you take a long trip: 1.Start by taking subway train to airport. 2.Take plane to another city. 3.Rent car at destination. 4.Drive car to final destination. None of above vehicles accomplished entire trip from start to finish; takes planes, trains, and automobiles! Routers Separate a Network into Separate Data Links 48 Figure 3-24

49 IP Addressing Identifies device in TCP/IP network. Every device must have unique IP address. IP address has 32 bits written in dotted decimal notation (DDN) of four sets of eight bits each with dot (period) between each number. Networking devices see decimal numbers as binary. Binary IP Address Equivalent Decimal IP Address Example IP Addresses, Binary and DDN Formats 49 Table 3-1

50 IP Addressing Each PC with a connection into the TCP/IP network has a unique IP address. IP Addresses in a Network Diagram 50 Figure 3-25

51 IP Addressing Routers play a big role with the IP protocol in that t they route (forward) data based on the destination IP address. To do that, a router must connect using multiple interfaces to multiple data links. Example: Each router has 2 interfaces: One for WAN link and one for LAN. Routers: Multiple Interfaces, Multiple IP Addresses 51 Figure 3-26

IP Addressing Grouping To make IP routing work,

Rules give network engineers flexibility in how

52 IP Addressing Grouping To make IP routing work, addresses grouped using rules. IP groups addresses in different ways: Classful networks and subnetting. Rules give network engineers flexibility in how they assign addresses, but still allow IP routing to work efficiently. Five Classful IP Networks 52 Figure 3-27

53 IP Addressing Grouping IP Classful l Networks Class IP Range Designed for A B C Large enterprises, government agencies, etc. Medium-sized businesses, organizations, etc. For small entities and home networks D Multicast E Experimental, research Five Classful IP Networks 53

54 IP Addressing Update IPv6 IP version 4 addresses no longer issued out (all used). Based on 32-bit addresses , dotted decimal. IP version 6 is new IP addressing scheme. Based on 128-bit address. Expressed in 8 sets of 4 hexadecimal numbers, for example: 2001:0db8:85a3:0000:0000:8a2e:0370:7334. Creates billions and billions of IP addresses: 2 128, or approximately (a number with 37 zeros). For all practical purposes, eliminates classful networks and need for subnetting. World IPv6 Launch took place on 6 June Five Classful IP Networks 54

55 IP Routing IP routing defines exactly how routers forward data in network. Each router connects to multiple physical links so has multiple physical interfaces (ports). Router has rules that tell it how to make routing decisions. IP routing relies on two ideas: Sender addresses data. Routers forward data based on destination IP address. 55

56 IP Routing Moving data on network relies on routers to forward data to correct destination host. Routers talk to each other (using protocols) to learn about IP addresses in network. Routers keep routing information in their RAM in IP routing tables. Routing Tables on R1 and R2, for Network Figure 3-29

57 IP Routing PC11 sends an IPv4 packet to PC21 by adding an IP header that t includes its address and the destination s IPv4 address to the data (payload). Web Client Host PC11 Puts into the IP Header Destination IP Address Field 57 Figure 3-28

IP Routing 1. PC11 sends data with destination IPv4 address 12.1.1.21 (PC21) to R1. 2. R1 compares destination IP address listed in header with its routing table.

58 IP Routing 1. PC11 sends data with destination IPv4 address (PC21) to R1. 2. R1 compares destination IP address listed in header with its routing table. R1 finds matching table entry that tells R1 to send data (R2). 3. R21sends packet to router R2. 4, 5. R2 s routing table says that network IPv is local so R2 forwards data over LAN directly to PC21. 58

59 Forwarding Packets IP creates and adds IP header to payload. Sending host adds IP header (Network Layer address) and Data Link layer header/trailer before sending data onto network. IP header follows Data Link header in frame. Encapsulation on the Sending Host: Frame and Packet 59 Figure 3-30

60 Forwarding Packets Frame: Encapsulated data that t includes Data Link header and trailer plus everything in between (including IP header). Packet: What sits between Data Link header and trailer. Router discards Data Link header and trailer when it receives frame, leaving IP packet. Router then encapsulates packet into new Data Link header and trailer (with next hop Data Link address) when it forwards IP packet. Encapsulation/de-encapsulation process continues until IP packet delivered to destination. 60

61 Routing IP Packets Routers: Remove Packet from Frame, Send Packet inside a New Frame 61 Figure 3-31

62 Routing IP Packets 1. Sending host sends Ethernet frame to router. 2. Router: a. Removes IP packet from inside frame and discards old Data Link header/trailer. b. Decides where to route IP packet (to next router across WAN link). c. Encapsulates packet in new PPP frame and sends across link. 3. PPP frame holds original IP packet as it crosses WAN link to destination router. 4. Destination router repeats same three steps as sending router. 5. Ethernet frame (with original IP packet) crosses LAN and arrives at destination device. 62

63 Transport Protocols Transport layer protocols provide the connection to network applications (apps). Widening Scope of Higher TCP/IP Layers 63 Figure 3-32

64 Transport Protocols TCP and UDP Transport layer connects source and destination applications. Port number: Used by transport protocol to identify each destination app. Transmission Control Protocol (TCP) Connection- oriented. User Datagram Protocol (UDP) Connectionless. 64

65 TCP/IP Roles Summary, Part 1 TCP/IP network delivers bits from one device to another and from one application to another. Applications run on various devices. Application vendors use protocols that let apps communicate through network. Application layer protocols rely on Transport layer protocols to connect sending app to destination app. 65

66 TCP/IP Roles Summary, Part 2 Each application s writer chooses to use TCP, UDP, or some other less common Transport protocol. TCP and UDP use port numbers (specified in header) that identify destination app. Transport layer protocols rely on IP to deliver packets from sending host to destination host. Sending host adds IP header which includes destination IP address. Each router reacts to destination IP address to make routing choice. 66

67 TCP/IP Roles Summary, Part 3 IP defines details to make network communication possible, including logical IP addressing and routing. IP relies on Data Link and Physical layers to deliver frames across LANs and WANs. Data Link layer defines how to best use physical link, and adds Data Link headers/trailers that contain delivery information (MAC addresses). Physical layer defines how to encode bits over cable or wirelessly. 67

68 TCP/IP Roles Summary, Part 4 Layer Name Key Functions Physical Data Link Internetwork (Network) Transport Application Physical parts that communicate, and energy over those parts (electricity, light, radio). Rules about when to use physical links; Addressing specific to the physical links. Logical addressing (addressing independent of the physical links); routing. Communications functions useful to apps, but likely useful to many apps. Communication functions specific to a particular app. Host or Network Network Network Network Host Host Device Focus Cables, radio LAN Switch Router Any endpoint device Any endpoint device TCP/IP Model Summary 68 Table 3-2

69 Summary: This chapter Distinguished between the key terms related to networking standards, including standard, protocol, and model. Listed the layers of the TCP/IP model and explained the purpose of the TCP/IP model. Named standards organizations on which the TCP/IP model relies. Briefly compared the history of the OSI and TCP/IP models and classified the layers of each in comparison to each other. 69

70 Summary: This chapter Summarized the key functions of Ethernet LANs. Summarized the key functions of leased line WANs. Explained how IP addressing and IP routing work together. Defined how different headers help move data through a network. Listed two Transport layer protocols: TCP and UDP. 70

71 Questions? Comments? 71

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