TCP

1. TCP/IP Communications version 05/25/2002

2. LAYERS APPLICATION ROI SOFTWARE OS/400 OPERATING SYSTEM AS/400 HARDWARE COMM PORT

3. History of TCP/IP - 1948 Bolt Beranek and Newman, played a major role in creating the Internet, and was founded in 1948 as consulting company. Richard Bolt and Leo Beranek were acousticians from MIT who did private consulting on buildings around the country. In the Mid 1940�s Bolt was asked by the United Nations to design the acoustics for a new building. Because of all the work that was ahead, he asked Leo Beranek to join him. Another man, Robert Newman, and they formed BBN.

4. History of TCP/IP - 1960 J.C.R. Licklider was first interested in computers when he worked at MIT�s Lincoln Laboratory. He studied the computer and became interested in the relationship between man and computers. In 1960 he wrote "Man-Computer Symbiosis" about the computer and man�s dissimilarities. He gave the example of a Fig tree and the insect Blastophaga Grossorum. The insect pollinates the tree and the and the fig tree houses the insect. Both can�t live without each other, but are completely dissimilar organisms. Licklider explains the symbiosis of man and computer to come

5. History of TCP/IP � 1960s Forty years ago, interactive computer networks did not exist anywhere except in the minds of a handful of computer scientists. In 1966, the Defense Department's Advanced Research Projects Agency funded a project to create computer communication among its university-based researchers. The experiment was inspired by J.C.R. Licklider, a brilliant research scientist from MIT, and Robert Taylor, the Director of the ARPA office that funded it.

6. History of TCP/IP - 1960 �In the anticipated symbiotic partnership, men will set the goals, formulate the hypotheses, determine the criteria, and perform the evaluation. Computing machines will do the routinizable work that must be done to prepare the way for insights and decisions in technical and scientific thinking.� J.C.R. Licklider, 1960 Licklider was the first to believe that computers could be used for more that just large calculators but instead they could perform scientific thinking.

7. History of TCP/IP � late 1960s TCP and IP were developed by a Department of Defense (DoD) research project to connect a number of different networks designed by different vendors into a network of networks. The project was initially successful because it provided a few basic services everyone needed, including file transfer, electronic mail and remote logon.

8. History of TCP/IP � late 1967 By the end of 1967 Larry Roberts wrote his first proposal on the soon to be "ARPA net" using the hosts, or Interface Message Processor (IMP), and Paul Barans and Donald Davies idea of Packet switching. Roberts decided UCLA, Stranford Research Institute (SRI), University of Utah and the University of California would be the first four institutes to receive the IMPs for the network. In July, 1968, Larry Robert sent out a proposal for building the IMPs to over 140 companies, and more than 12 responded.

9. History of TCP/IP � September 1968 BBN�s proposal stated that the IMP would be create using Honeywell DDP-516�s because of its reliability and multiple function capability. Little did they know that the by the time they finished writing the proposal on September 6, 1968, it would be over 200 pages long at a cost of over $100,000. The small group of close-knit workers would soon be referred as the IMP guys for their achievements in creating the first Information Message Processors.

10. History of TCP/IP � December 1968 In December 1968, the Advanced Research Projects Agency (ARPA) awarded Bolt Beranek and Bewman a contract to design and deploy a packet switching network. The project was called ARPANET and four nodes were in place by the end of 1969 and connections to Europe were made by 1973.

11. History of TCP/IP - 1970 By the summer of 1970, MIT, RAND,System Development Corp. and Harvard got IMP numbers 6 to 9 respectively, a second high speed cross continent line of 50 Kilobits was added from BBN to RAND making a total of two cross continent high speed lines. BBN wanted to create a smaller IMP. By the end of 1970, ARPA OK�d funding development of the new Honeywell 316 to replace the old, large 516. One problem with the old IMP was supporting a maximum of ONLY four terminals at a time. People were requesting multiple terminal connections.

12. History of TCP/IP - 1971 One of the first RFCs related to sockets was RFC number 147 which was published by Joel M. Winett on May 7, 1971. It defines a socket (for ARPAnet.) A socket is a pair of IP addresses and port number. Sockets are actually stored in a computer as 32-bit numbers.

13. History of TCP/IP - 1972 The next problem in the new ARPAnet was that there was no standard means of transferring files over the network. A group of researchers got together for six months and came up with a File Transfer Protocol (FTP) that would specify the format of the information that would travel over the ARPAnet. It was completed in July 1972.

14. History of TCP/IP - 1973 The initial host-to-host communications protocol used in ARPANET was the Network Control Protocol (NCP). NCP proved to be unable to keep up with the growing network traffic load.

15. History of TCP/IP � 1973 Spring Vint Cerf and Bob Kahn were thinking of connecting the ARPAnet with other networks. Cerf was at a conference were he started to draw an a paper what he thought could be the way to connect the networks. At that time there were two other types of networks called SATNET (satellite networking) and packet radio. They realized that they need a link or "gateway" to connect the network together in a way that it would appear the same for each network.

16. History of TCP/IP � 1973 Summer That summer the two of them worked out a proposal on a "Protocol for Packet Network Inter-communication". They described the new protocol like an envelope that carries parts of a letter inside, were the broken up letter are called "datagrams." It didn�t mater to any network what was inside the letter, only that the envelope reaches it�s destination in one piece, if it didn�t, a new letter would be sent. The new protocol, which would be essential for networks to communicate with each other, was called the Transmission-Control Protocol (TCP).

17. History of TCP/IP � 1973 @ The famous @ symbol in every email address was created in 1973 by Ray Tomlinson at BBN. He was working to send messages over the ARPAnet. He developed SNDMSG and the first File Transfer Protocol called CPYNET which would send electronic messages over the ARPAnet. Tomlinson had to separate the user name from the computer name. He looked at his Model 33 Teletype and chose the @ symbol as the separator. By 1977, BBN used the Transmission Control Protocol (TCP) for the first time on a UNIX system.

18. History of TCP/IP - 1974 The Transmission Control Protocol (TCP) and the Internet Protocol (IP) were proposed and implemented in 1974 as a more robust suite of communications protocols. Both protocols have had revisions with the most notable being IP version 6 which was released in December 1995.

19. History of TCP/IP - 1978 During a discussion between Vint Cerf, John Postel and Danny Cohen in 1978, they decided to split TCP into two separate functions: TCP and the Internet Protocol (IP). TCP would break up the datagrams and messages, reassembling them at the destination. IP would transmit the individual datagrams. For example: the TCP protocol would split up the letter and place it into multiple envelopes, while the IP protocol would be in charge of addressing the envelope and making sure it arrived at its proper destination.

20. History of TCP/IP � early 1980s The Army puts out a bid for computers and DEC wins. The Air Force puts out a bid and IBM wins. The Navy bid is won by Unisys. Then the President decides to invade Grenada in 1983 and the armed forces discover that their computers cannot talk to each other. The DOD must build a "network" out of systems each of which, by law, was delivered by the lowest bidder on a single contract.

21. History of TCP/IP- Internet Birth By the late 1970�s and early 80, many new networks formed. Some were CSNET(Computer Science Research Network), BITnet (Because It�s Time network), SPAN (Space Physics Analysis Network), CDnet (Canadian Network) and one of the largest: the NSFnet or National Science Foundation Network. By the late 1970�s, most were using the new TCP/IP protocol. It wasn�t until January 1, 1983 that ARPAnet changed over to the new protocol. This day became the official birth date of the Internet.

22. History of TCP/IP- 1983 In 1983, the DoD mandated that all of their computer systems would use the TCP/IP protocol suite for long-haul communications. 1983 saw a huge increase in the popularity of TCP/IP when the University of California at Berkeley included TCP/IP in the communications kernel for 4.2BSD Unix.

23. History of TCP/IP � 1986 In 1986, Berkeley released a new version of Unix, BSD 4.3, with substantial improvements to the TCP/IP networking code.

24. History � 1989 - Death of ARPAnet By 1989 the Internet was becoming more and more commercialized and less for the research community, the newer and much more faster NSFnet had far more computers than the ARPAnet. Unable to keep up with new technologies and funding for the ARPAnet, DARPA finally decided that it was time to pull the plug on the 22 year old network. The man who slowly disconnected the ARPAnet computers and connected them to the NSFnet back bone was Mark Pullen.

25. History of TCP/IP - 1990 The DoD mandated that all of its computer systems use OSI protocols by August 1990 and phase out all use of TCP/IP. Development of TCP/IP continued despite the mandate and is still in widespread use.

26. Ethernet Ethernet version 2 released in 1982 was originally developed by Xerox-Intel-DEC. In 1985 the IEEE released a new standard for ethernet. This standard is named IEEE 802.2. In general, these two versions of ethernet can inter-operate.

27. Big MAC Ethernet addresses a host using a unique, 48-bit address called its Ethernet address or Media Access Control (MAC) address. MAC addresses are usually represented as six colon-separated pairs of hex digits, e.g., 8:0:20:11:ac:85. This number is unique and is associated with a particular Ethernet device. The data link layer's protocol-specific header specifies the MAC address of the packet's source and destination.

28. Dotted Decimals IP addresses are written as four dot-separated decimal numbers between 0 and 255, e.g., 129.79.16.40. The leading 1-3 bytes of the IP identify the network and the remaining bytes identifies the host on that network.

29. Connect the Dots

30. Address Classes To support different size networks, the TCP/IP designers decided that the IP address space be divided into three different address classes - Class A, Class B, and Class C. This is often referred to as "classful" addressing because the address space is split into three predefined classes, groupings, or categories. Each class fixes the boundary between the network-prefix and the host-number at a different point within the 32-bit address.

31. Address Classes

32. Class A (/8 Prefixes) Each Class A network address has an 8-bit network-prefix with the highest order bit set to 0 and a seven-bit network number, followed by a 24-bit host-number. A maximum of 126 (27 -2) /8 networks can be defined. The calculation requires that the 2 is subtracted because the 0.0.0.0 is reserved for use as the default route and the 127.0.0.0 (also written 127/8 or 127.0.0.0/8) has been reserved for the "loopback" function.

33. Host Capacity Calculation Each /8 supports a maximum of 16,777,214 (224 -2) hosts per network. The host calculation requires that 2 is subtracted because the all-0s ("this network") and all-1s ("broadcast") host-numbers may not be assigned to individual hosts. Since the /8 address block contains 231 (2,147,483,648 ) individual addresses and the IPv4 address space contains a maximum of 232 (4,294,967,296) addresses, the /8 address space is 50% of the total IPv4 unicast address space.

34. Class B (/16 Prefixes) Each Class B network address has a 16-bit network-prefix with the two highest order bits set to 1-0 and a 14-bit network number, followed by a 16-bit host-number. A maximum of 16,384 (214 ) /16 networks can be defined with up to 65,534 (216 -2) hosts per network. Since the entire /16 address block contains 230 (1,073,741,824) addresses, it represents 25% of the total IPv4 unicast address space.

35. Class C (/24 Prefixes) Each Class C network address has a 24-bit network-prefix with the three highest order bits set to 1-1-0 and a 21-bit network number, followed by an 8-bit host-number. A maximum of 2,097,152 (221 ) /24 networks can be defined with up to 254 (28 -2) hosts per network. Since the entire /24 address block contains 229 (536,870,912) addresses, it represents 12.5% (or 1/8th) of the total IPv4 unicast address space.

36. Dotted Decimal Ranges

37. Growing Problems Internet routing tables were beginning to grow.

38. IP Routing Growth

39. Growing Problems Local administrators had to request another network number from the Internet before a new network could be installed at their site.

40. IP Address Growth

41. The SUBNET MASK The subnet mask was the forerunner of the modern IP address prefix length. When configuring a host, both a 32-bit dotted-quad IP address and a 32-bit dotted-quad subnet mask was specified. The subnet contains a one bit in every position where the prefix is valid and must match, and a zero bit in every remaining position, where the prefix is ignored. Since 255 is 11111111 (eight ones) in binary, a mask of 255.255.0.0 has sixteen one bits and corresponds exactly to a prefix length of /16.

42. Subnet Masking of Zorro

43. Configuring Multiple Internal Networks with Subnetting

44. The Mask

45. How we Mask �em at ROI Class C public address space 207.235.75.0/24 Subnet mask 255.255.255.0 (256 � 2) available Class B private address space 192.168.1.0 Subnet mask 255.255.0.0 256 x 256 = 65.536 � (2 x 256)

46. Subnet Benefits Global Internet routing table does not grow. Admin needs no more addresses. Routing for all subnets combined into single routing table entry. Admin deploys additional subnets without obtaining a new network number from the Internet. Route changing within private network not affect the Internet routing table, which knows about the reachability of only the parent network number.

47. Classless Inter-Domain Routing (CIDR) By 1992, the exponential growth of the Internet was beginning to raise serious concerns about the ability of the Internet's routing system to scale and support future growth. The near-term exhaustion of the Class B network address space The rapid growth in the size of the global Internet's routing tables The eventual exhaustion of the 32-bit IPv4 address space

48. CIDR CIDR was officially documented in September 1993: CIDR eliminates the concept of Class A, B, and C network addresses. Allows efficient allocation of the IPv4 address space which will allow the continued growth of the Internet until IPv6 is deployed. CIDR supports route aggregation where a single routing table entry can represent the address space of perhaps thousands of traditional classful routes. This allows a single routing table entry to specify how to route traffic to many individual network addresses.

49. Bootleg CIDR Without the rapid deployment of CIDR in 1994 and 1995, the Internet routing tables would have in excess of 90,000 routes (instead of the current 40,000+) and the Internet would probably not be functioning today!

50. CIDR Diagrammed

51. Classful Wasteful Partitioning

52. Classless Efficient Partitioning

53. Reduces Routing Table Size

54. ARP, ARP Even though IP packets are addressed using IP addresses, hardware addresses must be used to actually transport data from one host to another. The Address Resolution Protocol (ARP) is used to map the IP address to it hardware address.

55. ARP Table Example ---------------------------------- IP address Ethernet address ---------------------------------- 192.168.1.1 08-00-39-00-2F-C3 192.168.1.3 08-00-5A-21-A7-22 192.168.1.4 08-00-10-99-AC-54 ----------------------------------

56. Send a DATAGRAM TCP/IP is a connectionless service. This means that when a large block of data is broken up into smaller pieces (datagrams) and sent to another host, the network is not aware that these individual datagrams are all related to each other. Datagrams often take different routes and arrive in different orders than those in which they were sent. TCP is well equipped to put all the datagrams back together, in the right order and in the right data block.

57. Getting a Header One job for TCP is to add a header to each datagram so the receiving end knows which connection each datagram belongs to. This is called multiplexing. The header contains the following information:

59. International Standards Organization Open System Interconnect Layers ISO/OSI

61. ISO/OSI Layer 1 Physical - Physical layer defines the cable or physical medium itself, e.g., thinnet, thicknet, unshielded twisted pairs (UTP). All media are functionally equivalent. The main difference is in convenience and cost of installation and maintenance. Converters from one media to another operate at this level.

62. ISO/OSI Layer 2 Data Link - Defines the format of data on the network. A network data frame, aka packet, includes checksum, source and destination address, and data. The data link layer handles the physical and logical connections to the packet's destination, using a network interface. A host connected to an Ethernet would have an Ethernet interface to handle connections to the outside world, and a loopback interface to send packets to itself.

63. ISO/OSI Layer 3 Network - Internetwork Protocol (IP) is a common network layer interface. IP is responsible for routing, directing datagrams from one network to another. The network layer may have to break large datagrams into smaller packets and host receiving the packet will have to reassemble the fragmented datagram. The Internetwork Protocol identifies each host with a 32-bit IP address.

64. ISO/OSI Layer 4 Transport - Transport layer subdivides user-buffer into network-buffer sized datagrams and enforces desired transmission control. Two transport protocols, Transmission Control Protocol (TCP) and User Datagram Protocol (UDP), sits at the transport layer. Reliability and speed are the primary difference between these two protocols.

65. ISO/OSI Layer 5 Session - The session protocol defines the format of the data sent over the connections. The NFS uses the Remote Procedure Call (RPC) for its session protocol. RPC may be built on either TCP or UDP. Login sessions uses TCP whereas NFS and broadcast use UDP.

66. ISO/OSI Layer 6 Presentation - External Data Representation (XDR) sits at the presentation level. It converts local representation of data to its canonical form and vice versa. The canonical uses a standard byte ordering and structure packing convention, independent of the host.

67. ISO/OSI Layer 7 Application - Provides network services to the end-users. examples of network service applications: Mail � POP and SMTP File Transfer - ftp Sessions - telnet Name Management - DNS

69. IBM System Network Architecture IBM/SNA

70. SNA

71. TCP/IP Functions Computer Mail File Transfer Remote Login Network File Systems Remote Printing Remote Execution Name Servers Terminal Servers

72. TCP/IP Protocol Stack Although the OSI model is widely used and often cited as the standard, TCP/IP protocol has been used by most Unix workstation and server vendors. TCP/IP is designed around a simple four-layer scheme. It omits some features found in OSI. It combines features of some adjacent OSI layers and splits other layers apart.

73. Organized Organizations The DOD (Department of Defense) invented the four-layer TCP/IP model. Her, we compare it to the similar, seven-layer model designed by ISO, the International Standards Organization. While these organizations developed the framework for network protocols, still more organizations are responsible for developing the actual protocols, including the Institute of Electrical and Electronics Engineers (IEEE) and the Internet Engineering Task Force (IETF).

76. Major Differences � OSI vs. TCP/IP The application layer in TCP/IP handles the responsibilities of layers 5,6, and 7 in the OSI model. The transport layer in TCP/IP does not always guarantee reliable delivery of packets as the transport layer in the OSI model does. TCP/IP offers an option called UDP that does not guarantee reliable packet delivery.

77. Simplified Protocol Stack

78. Conceptual Protocol Stack ---------------------------- | network applications | | | |... \ | / .. \ | / ...| | ----- ----- | | |TCP| |UDP| | | ----- ----- | | \ / | | -------- | | | IP | | | ----- -*------ | | |ARP| | | | ----- | | | \ | | | ------ | | |ENET| | | ---@-- | ----------|----------------- | . --------o----------------- Ethernet Cable

79. TCP/IP Layer 1 Link/Network Access - Defines the network hardware and device drivers. Delivers data to devices on a directly attached network. Defines how to use the network to deliver IP datagrams. arp - maps MAC addresses to IP addresses.

80. TCP/IP Layer 2 Network/Internet - Basic communication, addressing and routing. Defines the datagram (packet) and addressing scheme. Routing of datagrams to remote hosts. Performs fragmentation and re-assembly of datagrams. TCP/IP uses IP and ICMP protocols here.

81. ICMP Internet Control Message Protocol Provides flow control Detects unreachable destinations Redirects routes Can check remote hosts (ping)

82. TCP/IP Layer 3 Transport - Handles communication among programs on a network. TCP and UDP falls within this layer.

83. TCP/IP Layer 4 Layer 4 - Application - End-user applications reside at this layer. Gets data from the transport layer (UDP and TCP) by binding to ports. TCP examples include: ftp, telnet, smtp, http, nntp UDP examples include: dns, rip, nfs, snmp, dhcp/bootp

84. Sockets, b. 1981 First appeared in Berkeley Unix in 1981 (BSD 4.2 InterProcess Communications - IPC) Supported on virtually every operating system: Windows socket API is WinSock BSD Unix systems (as part of the kernel) MS-DOS, Windows, Mac-OS and OS/2 (socket libraries) Java, as part of core classes (package java.net )

85. Sockets Consist of: IP address: 192.168.1.15 Port number: 1-65535 1-1024= well-known ports 1025-65535= user defined Notation: 192.168.1.15:1024

86. Stream Socket - TCP Provides for the bi-directional, reliable, sequenced, and unduplicated flow of data without record boundaries. A pair of connected stream sockets provides an interface nearly identical to that of pipes.

87. Datagram Socket - UDP Supports bi-directional flow of data that is not promised to be sequenced, reliable, or unduplicated. A process receiving messages on a datagram socket may find messages duplicated and possibly out of order. Importantly, record boundaries in the data are preserved. Datagram sockets closely model the facilities found in many contemporary packet switched networks such as the Ethernet.

88. Raw Socket Provides access to the underlying communication protocols that support socket abstractions. These sockets are normally datagram oriented, although their exact characteristics are dependent on the interface provided by the protocol. Raw sockets are not for the general user.

89. QUESTIONS ?