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Chapter 15 - Networks I

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Chapter 15 - Networks I

  1. 1. Networks I Chapter 15
  2. 2. Chapter Objectives <ul><li>Understand basic network terminology. </li></ul><ul><li>Understand the basics of the TCP/IP protocol suite. </li></ul><ul><li>Understand the basics of IP addresses. </li></ul><ul><li>Understand basic IP routing. </li></ul><ul><ul><li>Understand the basics of ARP, and DNS. </li></ul></ul><ul><ul><li>Understand the basics of layer 2 and layer 3 “routing”. </li></ul></ul><ul><li>Understand common network hardware. </li></ul>
  3. 3. Network Protocols <ul><li>Internetworking - the process of connecting two computer networks together. </li></ul><ul><ul><li>The interconnected networks may or may not use the same network technology. </li></ul></ul><ul><ul><li>The interconnected networks may or may not be in the same location. </li></ul></ul><ul><ul><li>The interconnected networks may or may not encompass the same hardware. </li></ul></ul><ul><ul><li>The interconnected networks may or may not employ the same software. </li></ul></ul><ul><ul><li>The Internet is one example of internetworking. </li></ul></ul>
  4. 4. Network Protocols <ul><li>WARNING : </li></ul><ul><ul><li>Networking seems to encompass every two, three, four, five, and six character combination of letters into an acronym. </li></ul></ul>
  5. 5. Network Protocols (ISO) <ul><ul><li>The International Standards Organization adopted a networking model called the Open System Interconnect. </li></ul></ul><ul><ul><li>This network model breaks the task of networking down into seven layers (then arranged them like a top-ten list): </li></ul></ul><ul><ul><ul><li>7) Application layer - Provide end-user services </li></ul></ul></ul><ul><ul><ul><li>6) Presentation Layer - Deal with problems & compression </li></ul></ul></ul><ul><ul><ul><li>5) Session Layer - Authentication and Authorization </li></ul></ul></ul><ul><ul><ul><li>4) Transport Layer - Guarantee end-to-end (correct) delivery </li></ul></ul></ul><ul><ul><ul><li>3) Network Layer - Routing and Accounting </li></ul></ul></ul><ul><ul><ul><li>2) Data Link Layer - Transmit/receive packets & addressing </li></ul></ul></ul><ul><ul><ul><li>1) Physical Layer - The cable or media itself </li></ul></ul></ul>
  6. 6. Network Protocols (ISO) <ul><li>The ISO/OSI model was the result of design by committee. </li></ul><ul><li>The layers had little base in reality: They did not match real-world protocol stacks. </li></ul><ul><li>The ISO/OSI model suffered a horrible “death” (nobody could make it work). </li></ul><ul><li>Network theory courses still hold the ISO model up as the “right way to do things.” </li></ul>
  7. 7. Network Protocols (TCP/IP) <ul><li>Internet Protocol (TCP/IP model) </li></ul><ul><ul><li>The TCP Protocol is designed around a simplified four layer approach: </li></ul></ul><ul><ul><ul><li>Link Layer - Network hardware and device drivers </li></ul></ul></ul><ul><ul><ul><li>Network Layer - Basic Communications, addressing, routing </li></ul></ul></ul><ul><ul><ul><ul><li>The network layer protocol is the Internet Protocol (IP). </li></ul></ul></ul></ul><ul><ul><ul><li>Transport Layer - Communication among programs on a net. </li></ul></ul></ul><ul><ul><ul><ul><li>There are two data Transport protocols In TCP/IP: </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>User Datagram Protocol (UDP) </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Transmission Control Protocol (TCP) </li></ul></ul></ul></ul></ul><ul><ul><ul><li>Application Layer - End user application programs </li></ul></ul></ul><ul><ul><ul><ul><li>Utilities like ftp, ssh, rlogin, rsh, DNS, NFS, CIFS, … </li></ul></ul></ul></ul>
  8. 8. Network Protocols (TCP/IP)
  9. 9. Network Protocols (TCP/IP) <ul><li>In order for all of the computers on the Internet to communicate, we have to: </li></ul><ul><ul><li>Ensure that the computers speak the same language. </li></ul></ul><ul><ul><ul><li>The language used on the Internet is TCP/IP . </li></ul></ul></ul><ul><ul><ul><ul><li>IP is the Internet Protocol </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>IP provides a communication channel, including addressing, and routing. </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><li>TCP is the Transmission Control Protocol. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>UDP is the User Datagram Protocol.. </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>TCP and UDP provide data delivery over the IP channel. </li></ul></ul></ul></ul></ul><ul><ul><li>Ensure that each network device has a unique address . </li></ul></ul><ul><ul><li>Ensure that the computers have access to some form of bridging hardware in order to connect dissimilar network technologies. </li></ul></ul>
  10. 10. Network Protocols (TCP/IP) <ul><li>Internet Protocol (Packets) </li></ul><ul><ul><li>As a packet travels through the levels of the TCP/IP protocol, each layer adds it’s own header information to the datagram. </li></ul></ul><ul><ul><ul><li>This process of each layer encoding it’s own management information into the existing datagram is called nesting , or encapsulation . </li></ul></ul></ul><ul><ul><li>Various headers contain the source and destination address, checksum, protocol specific information, and other handling instructions. </li></ul></ul><ul><ul><li>At the receiving end the headers are stripped off by the appropriate level, the header contents are examined for special handling information, and the datagram is delivered to the appropriate application. </li></ul></ul>
  11. 12. Network Protocols (TCP/IP) <ul><li>Internet Protocol Version 4 (IPv4) </li></ul><ul><ul><li>An IP address consists of four byte values separated by periods. For Example: 123.45.67.89 </li></ul></ul><ul><ul><li>This notation is also known as the dotted quad format. </li></ul></ul><ul><ul><li>Each of the values must be in the range of 0 - 255 (8 bits). </li></ul></ul><ul><ul><li>An IPv4 address is therefore 32 bits (4 bytes * 8 bits/byte). </li></ul></ul><ul><li>There are five classes of IP Addresses in IPv4: </li></ul><ul><ul><li>Class A, B, and C addresses are used for single host addressing. </li></ul></ul><ul><ul><li>Class D addresses are used for multicast connections. </li></ul></ul><ul><ul><li>Class E addresses are experimental . </li></ul></ul>
  12. 13. Network Protocols (TCP/IP) <ul><li>Internet Protocol (IPv4) </li></ul><ul><ul><ul><li>Class A Networks - The first byte is in the range of 1 - 127. </li></ul></ul></ul><ul><ul><ul><ul><li>The first four bits of the address are Binary 0 X X X </li></ul></ul></ul></ul><ul><ul><ul><ul><li>There are 127 Class A networks. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>The first byte of a class A address is the network number. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>The remaining three bytes are the host address on that network. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>110 .32.4.18 </li></ul></ul></ul></ul><ul><ul><ul><ul><li>network host address </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Each Class A network can address up to 16 million hosts. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>All Class A networks are currently assigned and in use . (lie)! </li></ul></ul></ul></ul>
  13. 14. Network Protocols (TCP/IP) <ul><li>Internet Protocol (IPv4) </li></ul><ul><ul><ul><li>Class B Networks - The first byte in the range of 128 - 191. </li></ul></ul></ul><ul><ul><ul><ul><li>The first four bits of the address are BINARY 1 0 X X </li></ul></ul></ul></ul><ul><ul><ul><ul><li>There are 16,384 Class B networks. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>The first two bytes of a class B address are the network number. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>The remaining two bytes are the host address on that network. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>129.74. 25.98 </li></ul></ul></ul></ul><ul><ul><ul><ul><li>network host address </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Each Class B network can address up to 65,000 hosts. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Notre Dame holds a Class B license (129.74.X.Y) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>All Class B networks are currently assigned and in use. (lie)! </li></ul></ul></ul></ul>
  14. 15. Network Protocols (TCP/IP) <ul><li>Internet Protocol (IPv4) </li></ul><ul><ul><ul><li>Class C Networks - The first byte in the range of 192 - 223. </li></ul></ul></ul><ul><ul><ul><ul><li>The first four bits of the address are 1 1 0 X </li></ul></ul></ul></ul><ul><ul><ul><ul><li>There are 2,097,152 Class C networks. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>The first three bytes of a class C address is the network number. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>The remaining byte is the host address on that network. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>210.43.2 .8 </li></ul></ul></ul></ul><ul><ul><ul><ul><li>network host address </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Each Class C network can address up to 254 hosts. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Most of the Class C networks are assigned and in use. </li></ul></ul></ul></ul>
  15. 16. Network Protocols (TCP/IP) <ul><li>Internet Protocol (IPv4) </li></ul><ul><ul><ul><li>Class D Networks - The first byte in the range of 224 - 239. </li></ul></ul></ul><ul><ul><ul><ul><li>The first four bits of the address are 1 1 1 0 </li></ul></ul></ul></ul><ul><ul><ul><ul><li>These addresses are used for “one to many” communications (multicasting). </li></ul></ul></ul></ul><ul><ul><ul><li>Class E Networks - The first byte in the range of 240 - 254. </li></ul></ul></ul><ul><ul><ul><ul><li>The first four bits of the address are 1 1 1 1 </li></ul></ul></ul></ul><ul><ul><ul><ul><li>These addresses are reserved for experimental use by the IANA/IETF. </li></ul></ul></ul></ul>
  16. 17. Network Protocols (TCP/IP) <ul><li>The numbers 0, and 255 have special meaning in some fields of IP addresses. </li></ul><ul><ul><li>A Zero host address refers to “this network” </li></ul></ul><ul><ul><ul><li>For example 129.74.0.0 refers to the Class B network 129.74. </li></ul></ul></ul><ul><ul><li>A host address of all ones is called the broadcast address. </li></ul></ul><ul><ul><ul><li>For example 129.74.255.255 refers to all hosts on the 129.74 Class B network. </li></ul></ul></ul><ul><li>The address 127.0.0.1 is the loopback address. </li></ul><ul><ul><li>This address is used for inter-process communications, and for network testing. </li></ul></ul><ul><ul><li>All of the 127 network is reserved (127.0.0.0 - 127.255.255.255). </li></ul></ul>
  17. 18. Network Protocols (TCP/IP) <ul><li>Subnets and Supernets </li></ul><ul><ul><li>Subnets provide a way of chopping up large networks into smaller entities: </li></ul></ul><ul><ul><li>Networks might be split up to segment traffic. </li></ul></ul><ul><ul><li>Networks might be split up to facilitate better use of an assigned IP address space. </li></ul></ul><ul><ul><ul><li>A class A could be made to look like several class B/C networks. </li></ul></ul></ul><ul><ul><ul><li>A class B could be made to look like several Class C networks. </li></ul></ul></ul><ul><ul><ul><li>Even a Class C network can be sub-networked. </li></ul></ul></ul><ul><ul><li>To subnet a network, we apply a netmask. </li></ul></ul><ul><ul><ul><li>Standard netmask for Class A is 255.0.0.0 </li></ul></ul></ul><ul><ul><ul><li>Standard netmask for Class B is 255.255.0.0 </li></ul></ul></ul><ul><ul><ul><li>Standard netmask for Class C is 255.255.255.0 </li></ul></ul></ul><ul><ul><li>By logically ANDING the address and the netmask, we can determine the NETWORK portion of the address. </li></ul></ul>
  18. 19. Network Protocols (TCP/IP) <ul><li>Subnets </li></ul><ul><li>Network routers look at the destination IP address, and the netmask for the address to make delivery (routing) decisions. </li></ul><ul><ul><li>Once the router determines the class of the destination address, it consults a table to find the appropriate netmask. </li></ul></ul><ul><ul><ul><li>Class A netmask is 255.0.0.0 </li></ul></ul></ul><ul><ul><ul><li>Class B netmask is 255.255.0.0 </li></ul></ul></ul><ul><ul><ul><li>Class C netmask is 255.255.255.0 </li></ul></ul></ul><ul><li>For example, a packet bound from a random host on the Internet, to my office host would generate the following operation: </li></ul><ul><ul><li>129.74.25.98 = 10000001 . 01001010 . 00011001 . 01100010 </li></ul></ul><ul><ul><li>255.255.0.0 = 11111111 . 11111111 . 00000000 . 00000000 </li></ul></ul>10000001 . 01001010 . 00000000 . 00000000 == 129.74.0.0 or 129.74/16
  19. 20. Network Protocols (TCP/IP) <ul><li>The lab 129.74.46 network is subnetted into several smaller networks. </li></ul><ul><ul><li>By “stealing” bits from the host number, we can make the network number larger. This allows us to make a class B or C network look like many smaller (classless) networks. </li></ul></ul><ul><ul><ul><li>These networks are denoted by the formula N.S.H (network.subnet.host) </li></ul></ul></ul><ul><ul><li>By using a 27 bit netmask we can divide a network up into several “32” host networks. 11111111 . 11111111 . 11111111 . 11100000 </li></ul></ul><ul><ul><ul><li>27 bits of network address, 5 bits of host address. </li></ul></ul></ul><ul><ul><ul><ul><li>129.74.46.0 through 129.74.46.31 is one such network. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>129.74.46.32 through 129.74.46.63 is one such network. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>129.74.46.64 through 129.74.46.95 is one such network. </li></ul></ul></ul></ul><ul><ul><ul><li>129.74.46.32/27 denotes a host on a classless network which employs a 27 bit netmask. </li></ul></ul></ul><ul><ul><ul><li>This is referred to as Classless InterDomain Routing (CIDR) </li></ul></ul></ul>
  20. 21. Network Protocols (TCP/IP) <ul><li>Subnets and Supernets </li></ul><ul><ul><li>Supernets allow us to aggregate several smaller networks into one larger routing entity: </li></ul></ul><ul><ul><ul><li>This is the opposite of subnetting. </li></ul></ul></ul><ul><ul><ul><ul><li>Supernetting is employed to minimize routing table entries. </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>If an ISP has a customer who needs addresses for 400 hosts, a single class C address will not suffice. </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>By combining two class C networks, the ISP can make a single routing entity: </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>203.14.7.0 = 11001011 00001110 00000111 00000000 </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>203.14.6.0 = 11001011 00001110 00000110 00000000 </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>The first 23 bits are the same for both addresses so the ISP can advertise a single external route: </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>203.14.6/23 </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>This only works if the ISP also owns 203.14.4.0 and 203.14.5.0. </li></ul></ul></ul></ul></ul>
  21. 22. Network Protocols (TCP/IP) <ul><li>Classless Inter Domain Routing (CIDR) </li></ul><ul><ul><li>CIDR is the result of incorporating subnetting and supernetting into the classful IP address structure. </li></ul></ul><ul><ul><ul><li>We are no longer limited to class A, B, and C addresses. </li></ul></ul></ul><ul><ul><ul><li>By passing the netmask along with the address we can make arbitrarily large/small networks, as we see fit, to simplify routing and network design. </li></ul></ul></ul><ul><ul><li>CIDR allows simplified routing tables. </li></ul></ul><ul><ul><li>CIDR is the basis of IPv6. </li></ul></ul><ul><ul><li>You may also hear the term Variable Length Subnet Mask (VLSM). </li></ul></ul><ul><ul><ul><li>This is the practice of using various length subnet masks within a single network domain. </li></ul></ul></ul>
  22. 23. Network Protocols (TCP/IP) <ul><li>Internet Protocol (IPv4 trivia) </li></ul><ul><ul><li>We are running out of addresses under the current (IPv4) addressing scheme. </li></ul></ul><ul><ul><li>If every class A, Class B, and Class C network address was in use using classful addresses, there would be ((127 * 16,000,000) + (16384 * 65,000) + (2,097,152 * 254)) (or 3,629,636,608) hosts on the Internet. (3.6 gigahosts) </li></ul></ul><ul><ul><ul><li>The remainder of the addresses are the “zero”, and “broadcast hosts (overhead). </li></ul></ul></ul><ul><ul><ul><li>If subnetworking is in use, even more of the address space is lost to “overhead”. </li></ul></ul></ul><ul><ul><li>Real Soon Now a new version of IP will be released. This version is known as IPV6 (Internet Protocol version 6). </li></ul></ul>
  23. 24. Network Protocols (TCP/IP) <ul><li>IPv6 </li></ul><ul><ul><li>Addresses go from 32 bit to 128 bit. </li></ul></ul><ul><ul><li>Addresses will be colon separated hexadecimal quads: </li></ul></ul><ul><ul><ul><li>0xFEDC:BA98:7654:3210:0123:4567:89AB:CDEF </li></ul></ul></ul><ul><ul><ul><li>0x0000:0000:0000:0000:0000:FFFF:222.33.44.55 </li></ul></ul></ul><ul><ul><ul><ul><li>Shorthand ::FFFF:222.33.44.55 </li></ul></ul></ul></ul><ul><ul><li>IPv6 will not contain address classes – but prefix ranges will have meaning (geographic regions). </li></ul></ul><ul><ul><li>IPv6 will use multicasts instead of broadcasting. </li></ul></ul><ul><ul><li>IPv6 will use CIDR routing </li></ul></ul><ul><ul><li>IPv6 will facilitate data encryption </li></ul></ul><ul><ul><li>IPv6 contains provisions for new services (bandwidth reservation, guaranteed signal quality, more multicasting) </li></ul></ul><ul><ul><li>IPv6 will provide 340 undecillion addresses </li></ul></ul><ul><ul><ul><li>340 with 24 zero’s after it </li></ul></ul></ul>
  24. 25. Network Protocols (TCP/IP) <ul><li>Internet Protocol (packet delivery) </li></ul><ul><ul><li>The Internet protocol actually uses multiple layers of addressing to deliver packets. </li></ul></ul><ul><ul><ul><li>Protocol addressed packet delivery is referred to as ISO Layer 3 (Network layer) routing. </li></ul></ul></ul><ul><ul><ul><li>In addition to the IP address, each network adapter card is assigned a unique hardware address (Media Access Controller or MAC address). </li></ul></ul></ul><ul><ul><ul><li>Ethernet MAC addresses are 6 bytes long. </li></ul></ul></ul><ul><ul><ul><li>MAC addresses of other network technologies vary from 2 bytes to 20 bytes in length. </li></ul></ul></ul><ul><ul><li>The mapping between the MAC address and the IP address is handled at the Link Layer of the TCP/IP stack by the Address Resolution Protocol ( ARP ). </li></ul></ul>
  25. 26. Network Protocols (TCP/IP) <ul><li>Address Resolution Protocol </li></ul><ul><ul><li>By design, the network interface (the board in the host) wants to communicate with another network interface board. </li></ul></ul><ul><ul><ul><li>Network interface boards work with multiple protocols. </li></ul></ul></ul><ul><ul><ul><li>This means that they must have a way of addressing other NICs that is independent of the software protocol address. </li></ul></ul></ul><ul><ul><ul><li>All packets on the media are addressed to another MAC address. </li></ul></ul></ul><ul><ul><li>If the packet is bound for a host not known to the local host what happens? </li></ul></ul><ul><ul><ul><li>One way to resolve such a MAC address is for the host to send out a broadcast packet saying “Hi, I’m at MAC address x:y:z:a:b:c, how do I get to MAC address f:g:h:i:j:k?”. </li></ul></ul></ul><ul><ul><ul><ul><li>If the host with address f:g:h:i:j:k is on the same network, it will reply and the address is resolved. </li></ul></ul></ul></ul>
  26. 27. Network Protocols (TCP/IP) <ul><li>Otherwise an intermediate can be programmed to reply “send the packet to me, and I will forward it for you.” </li></ul><ul><ul><li>In this case the packet is sent from the host’s MAC address to the MAC address of the intermediate! </li></ul></ul><ul><ul><ul><li>source addr = host MAC, </li></ul></ul></ul><ul><ul><ul><li>destination addr = intermediate MAC </li></ul></ul></ul><ul><ul><li>The intermediate then forwards the packet on the way to the final destination. </li></ul></ul><ul><ul><ul><li>source addr = intermediate MAC, </li></ul></ul></ul><ul><ul><ul><li>destination addr = next hop MAC </li></ul></ul></ul><ul><ul><li>The host software maintains a table (the ARP cache) of these MAC addresses. </li></ul></ul><ul><li>This is ISO layer 2 (Data Link Layer) routing (switching) </li></ul>
  27. 28. Network Protocols (TCP/IP)
  28. 29. Network Protocols (TCP/IP) <ul><li>Internet Protocol (packet addressing) </li></ul><ul><ul><li>IP addresses identify machines. </li></ul></ul><ul><ul><ul><li>This allows us to get a datagram from one host to another. </li></ul></ul></ul><ul><ul><ul><ul><li>How do we deliver data to programs and services on these hosts? </li></ul></ul></ul></ul><ul><ul><ul><li>The TCP and UDP protocols extend the IP addressing concept through the use of “ ports ”. </li></ul></ul></ul><ul><ul><ul><ul><li>A port is a two byte number that identifies a particular service. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>These port numbers are mapped to services through the /etc/services file. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Ports with numbers less than 1024 are called privileged ports. </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>These ports are (supposed to be) only accessible by root, in an attempt to prevent impostors. </li></ul></ul></ul></ul></ul>
  29. 31. Network Protocols (TCP/IP) <ul><li>Internet Protocol (packet addressing) </li></ul><ul><ul><li>Because humans have a difficult time dealing with all of these numbers (MAC address / IP address / Port number), the computers/services are also allowed symbolic names. </li></ul></ul><ul><ul><li>Computers do not understand these names…the computer wants to work with numbers. </li></ul></ul><ul><ul><ul><li>The names are mapped to numbers by a variety of means. </li></ul></ul></ul><ul><ul><ul><ul><li>The most commons means of mapping system names to IP addresses are the /etc/hosts file, Network Information Services (NIS), and the Domain Name Service (DNS). </li></ul></ul></ul></ul><ul><ul><ul><ul><li>I will talk more about how these name services work in a few days. </li></ul></ul></ul></ul>
  30. 32. Other Protocols <ul><li>NetBEUI </li></ul><ul><ul><li>Net Bios Extended User Interface </li></ul></ul><ul><ul><ul><li>An extension of NetBIOS. </li></ul></ul></ul><ul><ul><ul><li>Not a routable protocol, as it has no network layer. </li></ul></ul></ul><ul><ul><ul><li>Can have bridged networks, but not routers. </li></ul></ul></ul><ul><ul><ul><li>Relies on broadcasts for many functions. </li></ul></ul></ul><ul><ul><ul><li>Connection Oriented - Connectionless communications </li></ul></ul></ul><ul><ul><ul><li>Self configuration - self tuning </li></ul></ul></ul><ul><ul><ul><li>Error protection </li></ul></ul></ul><ul><ul><ul><li>Small memory overhead </li></ul></ul></ul><ul><ul><ul><li>Active Directory cannot use NetBEUI. </li></ul></ul></ul>
  31. 33. Other Protocols <ul><li>NetBIOS over TCP/IP (NBT) </li></ul><ul><ul><li>Replaces NetBEUI, allows applications to use TCP/IP </li></ul></ul><ul><li>Winsock </li></ul><ul><ul><li>Interface between socket based applications and TCP/IP. </li></ul></ul><ul><li>Server Message Block (SMB) networking. </li></ul><ul><ul><li>Used in previous versions of Windows. </li></ul></ul><ul><ul><li>Basis for Windows file and print sharing. </li></ul></ul><ul><ul><li>Uses NetBEUI - not routable. </li></ul></ul><ul><ul><li>Relies on Windows Internet Naming Services (WINS). </li></ul></ul><ul><ul><li>Being replaced by Common Internet File Service (CIFS). </li></ul></ul><ul><ul><ul><li>TCP/IP based networking for Windows! </li></ul></ul></ul><ul><ul><ul><li>Both SMB and WINS are unpublished protocols. </li></ul></ul></ul><ul><ul><ul><ul><li>Can change on a whim! </li></ul></ul></ul></ul>
  32. 34. Other Protocols <ul><li>AppleTalk </li></ul><ul><ul><li>Originally developed by Apple as a printer sharing protocol. </li></ul></ul><ul><ul><li>Later expanded to allow more complete network services. </li></ul></ul><ul><ul><li>Very little administration required. </li></ul></ul><ul><ul><ul><li>Hardware address is used, no IP address required. </li></ul></ul></ul><ul><ul><ul><li>Plug in a new machine, and it works! </li></ul></ul></ul><ul><ul><ul><ul><li>The new node sends a broadcast packet that says “Hi!, I’m Joe. I want to use address X. Does anyone object?” </li></ul></ul></ul></ul><ul><ul><ul><ul><li>If there is no objection, Joe is now at address X. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>If there is an objection, the node with the lowest address sends back a message stating “Hello Joe. I’m sorry, but you will have to use Y as your address, as X is already in use.” </li></ul></ul></ul></ul><ul><ul><li>Routers are very complex. </li></ul></ul><ul><ul><li>Works with a variety of hardware and media. </li></ul></ul><ul><ul><ul><li>Twisted pair, coaxial cable, Ethernet, PC’s UNIX hosts. </li></ul></ul></ul>
  33. 35. Other Protocols <ul><li>EtherTalk </li></ul><ul><ul><li>Actually AppleTalk over Ethernet. </li></ul></ul><ul><ul><li>Two flavors are available: </li></ul></ul><ul><ul><ul><li>Phase 1 was Apple’s first Ethernet network. It was very buggy, and tended to flood the network with broadcast packets. Phase 1 also had it’s own packet types which were not known by TCP/IP. </li></ul></ul></ul><ul><ul><ul><li>Phase 2 changed the broadcast packets to Multicast packets, and encapsulated their odd packets as acceptable packets. </li></ul></ul></ul>
  34. 36. Other Protocols <ul><li>LocalTalk </li></ul><ul><ul><li>Is actually Apple’s AppleTalk protocol implemented on twisted pair cabling. </li></ul></ul><ul><ul><ul><li>AppleTalk was originally implemented with an odd coaxial cable. </li></ul></ul></ul><ul><ul><li>Network speed reaches a blazing 230 Kilobits/second! </li></ul></ul><ul><ul><li>LocalTalk allows star topology with active or passive hubs and multiple hosts on a leg. </li></ul></ul><ul><ul><li>Ethernet to LocalTalk bridges are very common. </li></ul></ul><ul><ul><li>MacIP is used to encapsulate Ethernet packets in LocalTalk packets. </li></ul></ul>
  35. 37. Other Protocols <ul><li>AppleTalk </li></ul><ul><ul><li>AppleTalk addressing uses a multi-layer address system like IP. </li></ul></ul><ul><ul><li>The MAC address is hardware based. </li></ul></ul><ul><ul><li>The Node number is dynamically assigned by AppleTalk Address Resolution Protocol (AARP). </li></ul></ul><ul><ul><li>AppleTalk networks are grouped into zones. </li></ul></ul><ul><ul><li>Each AppleTalk entity has an object name (Billy Bob’s Office Printer), an object type (LaserWriter) as well as the zone name. </li></ul></ul><ul><ul><li>The zone entities are bound to network and node numbers by the AppleTalk Name Binding Protocol (ANBP). </li></ul></ul>
  36. 38. Other Protocols <ul><li>IPX </li></ul><ul><ul><li>IPX is the Internet Packet Exchange Protocol. </li></ul></ul><ul><ul><li>IPX was developed by Novell for the NetWare product. Novell is the most common network protocol in use for PC’s. </li></ul></ul><ul><ul><li>Novell is in the process of converting the Novell Network to use TCP/IP protocol. </li></ul></ul><ul><ul><li>Current IPX implementations use standard Ethernet packet headers. </li></ul></ul><ul><ul><li>Older versions of IPX used non-standard Ethernet packet headers, and would not co-exist on a network with non-IPX Ethernet packets. </li></ul></ul>
  37. 39. Other Protocols <ul><li>IPX </li></ul><ul><ul><li>IPX was derived from The Xerox Network System Internet Datagram Protocol (XNS IDP). </li></ul></ul><ul><ul><li>IPX uses a UDP like packet type. Headers have an unused checksum field, a packet length, packet type, a hop count, and the network, node, and socket numbers of the source and destination machines. </li></ul></ul><ul><ul><li>IPX packets are thrown away after 15 hops! </li></ul></ul><ul><ul><li>IPX is not a standardized protocol! It is a proprietary protocol and is subject to frequent unannounced changes. </li></ul></ul><ul><ul><li>Novell Loadable Modules (NLM’s) are available to add functionality to Novell IPX based networks. </li></ul></ul>
  38. 40. Other Protocols <ul><li>IPX </li></ul><ul><ul><ul><li>The IPX protocol has many “helper” protocols: </li></ul></ul></ul><ul><ul><ul><ul><li>Routing Information Protocol (RIP) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Sequenced Packet Exchanger : reliable delivery (SPX) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>ECHO (a packet echo facility) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>ERRORS (an error reporting facility) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Packet Exchange Protocol (PEP) </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>VERY inefficient, as it requires an ACK for each packet before the next packet is sent! </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>On top of PEP are the Network Core Products which provide authentication, file service, RPC, print spooling, accounting). </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><li>Service Advertisement Protocol (SAP) (address broker) </li></ul></ul></ul></ul>
  39. 41. Other Protocols <ul><li>DECnet </li></ul><ul><ul><li>DECnet is an implementation of the Digital Network Architecture (DNA) </li></ul></ul><ul><ul><li>DECnet first appeared in 1974. The first version to support Ethernet was DECnet phase IV released in 1984. </li></ul></ul><ul><ul><li>DECnet Phase V was released in 1991 and is referred to as DECnet/OSI. It supports TCP/IP, OSI, and Digital’s Network Services Protocol (NSP). </li></ul></ul>
  40. 42. Other Protocols <ul><li>DECnet </li></ul><ul><ul><li>DECnet Addressing is somewhat different from the other protocols: </li></ul></ul><ul><ul><li>DECnet addresses are independent of the transport media. </li></ul></ul><ul><ul><li>A DECnet address is a one byte “area” and a two-byte node number. </li></ul></ul><ul><ul><ul><li>An area is a logical grouping. </li></ul></ul></ul><ul><ul><ul><ul><li>One area may equate to one or more networks. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>One network may contain one or more areas. </li></ul></ul></ul></ul><ul><ul><ul><li>The machine’s address is derived from the area and node number, not the hardware MAC address. </li></ul></ul></ul><ul><ul><ul><li>All interfaces on the system use the same address! </li></ul></ul></ul>
  41. 43. Other Protocols <ul><ul><li>DECnet </li></ul></ul><ul><ul><ul><li>Until DECnet Phase V all routing tables were static. </li></ul></ul></ul><ul><ul><ul><li>Static routing limited DECnet to small network configurations. </li></ul></ul></ul><ul><ul><li>DECnet Phase V implemented dynamic routing via DECdns which is actually a distributed routing protocol. </li></ul></ul><ul><ul><ul><li>The routing is performed by DECnet routers. </li></ul></ul></ul><ul><ul><ul><li>A level one router routes information within one area. </li></ul></ul></ul><ul><ul><ul><li>A level two router routes information between two areas. </li></ul></ul></ul>
  42. 44. Protocol Translators <ul><li>As you may have guessed by now, there are ways to make systems running these “other” protocols talk to a TCP/IP network. </li></ul><ul><ul><li>Some of these protocols include TCP/IP modules. </li></ul></ul><ul><ul><li>Other protocols use a trick called “tunneling” to allow them to “talk on” TCP/IP networks. Tunneling is a form of packet encapsulation. </li></ul></ul><ul><ul><ul><li>In order for tunneling to work, the source and destination machines have to be on the same type of network. </li></ul></ul></ul><ul><ul><ul><ul><li>There may be one (or many) other types of networks between these two hosts and their networks. </li></ul></ul></ul></ul><ul><ul><li>Another method of interconnecting dissimilar networks requires special hardware/software which acts as a translator (bridges). </li></ul></ul>
  43. 46. Network Hardware <ul><li>Working With Current Network Hardware </li></ul><ul><ul><li>So far all we’ve talked about is the software side of networking. </li></ul></ul><ul><ul><ul><li>We saw that there are many different protocols in use on current communications networks. </li></ul></ul></ul><ul><ul><li>There is also a hardware component to networking. </li></ul></ul><ul><ul><ul><li>Unfortunately, there are almost as many hardware standards as there are protocols. </li></ul></ul></ul><ul><ul><ul><li>We will talk about four types of network hardware: </li></ul></ul></ul><ul><ul><ul><ul><li>Ethernet </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Token Ring </li></ul></ul></ul></ul><ul><ul><ul><ul><li>FDDI (token ring in disguise) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>ATM </li></ul></ul></ul></ul>
  44. 47. Network Hardware <ul><li>Working With Current Network Hardware </li></ul><ul><ul><ul><li>Network hardware has to take proximity into account. </li></ul></ul></ul><ul><ul><ul><ul><li>Local Area Networks (LANs) consist of machines in close proximity to each other. Example: Notre Dame campus, or networking within a small company building. </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>LANs typically employ high speed technologies ( 1Mb - 10 Gb / second throughput). </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><li>Metropolitan Area Networks (MANs) - consist of machines within a metropolitan area. Notre Dame could also be considered a Metropolitan Area Network. </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>MANs typically operate at lower speeds (56 Kb - 622 Mb / second throughput). </li></ul></ul></ul></ul></ul>
  45. 48. Network Hardware <ul><li>Working With Current Network Hardware </li></ul><ul><ul><ul><ul><li>Wide Area Networks (WANs) consist of machines separated by large distances. Example the Internet. </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>WANs typically operate at rates of 56 Kb to 622 Mb / second throughput. </li></ul></ul></ul></ul></ul><ul><ul><ul><li>The type of hardware selected for a network must be capable of working within the boundaries of the particular network. </li></ul></ul></ul>
  46. 49. Network Hardware <ul><li>Working With Current Network Hardware </li></ul><ul><ul><li>Ethernet - developed by Xerox in the 1970’s. </li></ul></ul><ul><ul><ul><li>Still has bugs ! </li></ul></ul></ul><ul><ul><ul><li>Ethernet is the most common network technology. </li></ul></ul></ul><ul><ul><ul><li>Ethernet employs Carrier Sense Multiple Access with Collision Detect to determine who gets to talk at any given time. </li></ul></ul></ul><ul><ul><ul><li>Ethernet does not include built-in error detection/correction. That is left to the software! </li></ul></ul></ul><ul><ul><ul><li>Most of the protocols we discussed run on Ethernet hardware. </li></ul></ul></ul><ul><ul><ul><li>Ethernet is a LAN technology that the users wanted (desperately) to become a WAN technology. </li></ul></ul></ul>
  47. 50. Network Hardware <ul><li>Working With Current Network Hardware </li></ul><ul><ul><ul><li>There are many flavors of Ethernet available: </li></ul></ul></ul><ul><ul><ul><ul><li>802.5 - Thicknet - 10Base-5 - Screaming Yellow 50 Ohm Coaxial cable. </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Attachment Unit Interface (AUI) connectors (DB15). </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>This is the oldest form of Ethernet. </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Length Limit 500 Meters / segment. </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Up to three segments connected via repeaters. </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>10 Mb/s shared bandwidth </li></ul></ul></ul></ul></ul>
  48. 52. Network Hardware <ul><li>Working With Current Network Hardware </li></ul><ul><ul><ul><ul><li>802.2 - Thinnet - 10Base-2 - cheapernet, </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Cheap coaxial cable </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>cheap BNC style connectors. </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>length limit: 200 Meters/segment. </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Up to two segments connected via repeater. </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Multiport repeaters allowed. </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>10 Mb/s shared bandwidth </li></ul></ul></ul></ul></ul>
  49. 54. Network Hardware <ul><li>Working With Current Network Hardware </li></ul><ul><ul><ul><li>10Broad36 - Broadband Ethernet. </li></ul></ul></ul><ul><ul><ul><ul><li>Not used very often </li></ul></ul></ul></ul><ul><ul><ul><ul><li>EXPENSIVE </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Multiplex Ethernet packets onto a broadband carrier system. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>36 Kilometer length limit </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Cable modems use similar technology. </li></ul></ul></ul></ul>
  50. 56. Network Hardware <ul><li>Working With Current Network Hardware </li></ul><ul><ul><ul><li>10BaseF - Fiber based Ethernet . </li></ul></ul></ul><ul><ul><ul><ul><li>Two fibers required (one for transmit, one for receive) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Optical to copper repeaters handle the collision detection. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Typical segments 2.2 Km maximum. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Multiple segments may be connected via repeaters </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Two repeaters/route maximum </li></ul></ul></ul></ul><ul><ul><ul><ul><li>10 Mb/s shared bandwidth </li></ul></ul></ul></ul>
  51. 58. Network Hardware <ul><li>Working With Current Network Hardware </li></ul><ul><ul><ul><li>10 BaseT - Twisted pair Ethernet </li></ul></ul></ul><ul><ul><ul><ul><li>Category 4 or Category 5 twisted pair wiring, or fiber. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Star topology - all hosts connect to hubs/routers/switches. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Length limit: 100 meters per connection, 500 meters between the two most distant hosts (if shared bandwidth). </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Cheap RJ45 connectors (telco style) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>10 Mb/s shared or switched bandwidth </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Switched connections allow full 10Mb/s to the host instead of shared bandwidth. </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Connections can be “full duplex” </li></ul></ul></ul></ul></ul>
  52. 59. Network Hardware <ul><li>Working With Current Network Hardware </li></ul><ul><ul><ul><li>100BaseT - Twisted pair Ethernet </li></ul></ul></ul><ul><ul><ul><ul><li>Category 4 or category 5 twisted pair wiring, or fiber. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Star topology - all hosts connect to hubs/routers/switches. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Length limit: 100 meters per connection </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Cheap RJ45 connectors (telco style) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>100 Mb/s switched bandwidth </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Switched connections allow full 100Mb/s to the host instead of shared bandwidth. Half, or Full Duplex connections. </li></ul></ul></ul></ul></ul>
  53. 61. Network Hardware <ul><li>Working With Current Network Hardware </li></ul><ul><ul><li>Token Ring Networks </li></ul></ul><ul><ul><ul><li>Token Rings utilize a special data structure called a token to determine who gets to talk. </li></ul></ul></ul><ul><ul><ul><li>Token Rings are typically built on a copper based media. </li></ul></ul></ul><ul><ul><ul><li>Token Rings are very common on PC systems, but not found very often on UNIX systems (with the exception of FDDI/CDDI). </li></ul></ul></ul><ul><ul><ul><li>Token Ring systems have two modes of operation: receive and transmit. </li></ul></ul></ul><ul><ul><ul><li>Typical Token Rings run at 1, 4, 10, or 16 Mbit/second. </li></ul></ul></ul>
  54. 63. Network Hardware <ul><li>Working With Current Network Hardware </li></ul><ul><ul><li>Fiber Distributed Data Interconnect (FDDI) </li></ul></ul><ul><ul><ul><li>FDDI is a token ring in disguise. </li></ul></ul></ul><ul><ul><ul><li>FDDI uses fiber optical cabling instead of copper. Copper Distributed Data Interconnect (CDDI) is FDDI over copper. </li></ul></ul></ul><ul><ul><ul><li>FDDI is capable of 100 Mbit/second data rates. </li></ul></ul></ul><ul><ul><ul><li>Single Attachment Stations (SAS) require a pair of fibers and have little fault tolerance. </li></ul></ul></ul><ul><ul><ul><ul><li>SAS FDDI networks are star-topology networks. </li></ul></ul></ul></ul><ul><ul><ul><li>Dual Attachment Stations (DAS) provide for fault tolerance and require two pairs of fibers. </li></ul></ul></ul><ul><ul><ul><ul><li>DAS FDDI networks are ring topology networks. </li></ul></ul></ul></ul>
  55. 66. Network Hardware <ul><li>Working With Current Network Hardware </li></ul><ul><ul><li>Automatic Teller Machines (ATM) </li></ul></ul><ul><ul><ul><li>ATM networks have been in use for many years by the banking industry. </li></ul></ul></ul><ul><ul><ul><li>Users put a card in a slot and can magically get money out of the ATM machine. </li></ul></ul></ul><ul><ul><li>OOPS. Sorry. Wrong ATM! </li></ul></ul>
  56. 67. Network Hardware <ul><li>ATM is part of a larger network: </li></ul><ul><ul><li>SONET (Synchronous Optical Network) is used for (extremely) high speed connections between telephone switches. </li></ul></ul><ul><ul><ul><li>Current Telco operations can handle 100 Gigabit/second over SONET. </li></ul></ul></ul><ul><ul><ul><li>Test frames currently running at 350+ Gb/second! </li></ul></ul></ul><ul><ul><li>Computer network hardware is available which allows you to use SONET connections between systems. </li></ul></ul><ul><ul><li>SONET is VERY expensive! </li></ul></ul>
  57. 68. Network Hardware <ul><li>Working With Current Network Hardware </li></ul><ul><ul><li>Asynchronous Transfer Mode (ATM) </li></ul></ul><ul><ul><ul><li>The basic foundations for ATM were developed by people who know about wide area networks and packet switching: Long Distance Telephone carriers. </li></ul></ul></ul><ul><ul><ul><li>ATM is the underlying technology behind the Broadband Integrated Services Digital Network (B-ISDN). </li></ul></ul></ul><ul><ul><ul><ul><li>B-ISDN is part of the “send a fax from the beach, tuck your kids into bed from around the world” technology. </li></ul></ul></ul></ul><ul><ul><ul><li>ATM is currently running with 622Mbit/second links. </li></ul></ul></ul><ul><ul><ul><ul><li>High-end Internet links are running at 155 Mbit/second. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>NOTE: Most hosts cannot drive such links at speeds over 350 Mbit/second. </li></ul></ul></ul></ul>
  58. 69. Network Hardware <ul><li>Working With Current Network Hardware </li></ul><ul><ul><ul><li>ATM comes in a variety of speeds. For example: </li></ul></ul></ul><ul><ul><ul><ul><li>25 Mbit/second IBM standard </li></ul></ul></ul></ul><ul><ul><ul><ul><li>45 Mbit/second Digital Service-3 (DS3) (T-3) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>51 Mbit/second SONET(OC-1) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>100 Mbit/second Taxi interface </li></ul></ul></ul></ul><ul><ul><ul><ul><li>155 Mbit/second Optical Carrier-3 (OC-3) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>622 Mbit/second Optical Carrier-12 (OC-12) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>1.2 Gbit/second Optical Carrier-24 (OC-24) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>2.4 Gbit/second Optical Carrier-48 (OC-48) </li></ul></ul></ul></ul><ul><ul><ul><li>Speeds are based on Telco transmission rates. </li></ul></ul></ul>
  59. 70. Network Hardware <ul><li>Working With Current Network Hardware </li></ul><ul><ul><li>ATM encompasses the Integrated Services Digital Network (ISDN), </li></ul></ul><ul><ul><ul><li>ISDN is used for (relatively) high speed connections to homes and businesses. A typical ISDN connection is actually a multiple-channel connection over telephone wire. </li></ul></ul></ul><ul><ul><ul><ul><li>ISDN uses two B channels, and a D channel. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>The B channels are 64 Kb/second data channels. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>The D channel is a 9.6 Kb/second signaling channel. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Current technology allows you to “bond” the two B channels together and use 4x data compression to get throughput up to 512 Kb/second. </li></ul></ul></ul></ul>
  60. 71. Network Hardware <ul><li>Working With Current Network Hardware </li></ul><ul><ul><li>xDSL technology (new) is similar to ISDN. </li></ul></ul><ul><ul><ul><li>ADSL (Asymmetric Digital Subscriber Loop) has one channel running at high speed, and one running at low speed (for example 512Kb/sec one direction, and 128 Kb/sec the other direction). </li></ul></ul></ul><ul><ul><ul><li>ADSL has been tested at rates up to 1.544 Mbit/second (same speed as a T1 link). </li></ul></ul></ul><ul><ul><ul><li>ADSL runs over standard telco wiring (ISDN and DSL require some tweaks to run over telco infrastructure). </li></ul></ul></ul>
  61. 72. Network Hardware <ul><li>Working With Current Network Hardware </li></ul><ul><ul><li>Because ATM is a telephone protocol, it has some odd “features” when used for data networking. </li></ul></ul><ul><ul><ul><li>ATM is a connection oriented service. No packets can be sent until a channel is opened. </li></ul></ul></ul><ul><ul><ul><ul><li>Ethernet/FDDI/Token Rings are all “ connectionless ”. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>IP is also connectionless. </li></ul></ul></ul></ul><ul><ul><ul><li>ATM sends/receives fixed length data cells, as opposed to the other technologies we discussed which send/receive variable length packets. </li></ul></ul></ul><ul><ul><ul><ul><li>Ethernet exchanges 64 - 1500 byte packets </li></ul></ul></ul></ul><ul><ul><ul><ul><li>FDDI exchanges 64 - 4500 byte packets </li></ul></ul></ul></ul><ul><ul><ul><ul><li>ATM exchanges 53 byte “cells” </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Each cell has a 5 byte header and 48 data bytes. </li></ul></ul></ul></ul></ul>
  62. 73. Network Hardware <ul><li>Working With Current Network Hardware </li></ul><ul><ul><li>ATM </li></ul></ul><ul><ul><ul><li>Fun with International Standards: </li></ul></ul></ul><ul><ul><ul><ul><li>The European telephone industry wanted ATM to use 16 byte cells for voice traffic, but would compromise up to 32 bytes. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>The United States telephone industry wanted 128 byte cells for data, but would compromise down to 64 bytes. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>The CCITT split the difference, and ATM cells were defined to be 48 bytes. </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Because headers were already defined as no more that 10% of the cell, headers became 5 bytes. </li></ul></ul></ul></ul></ul>
  63. 74. Network Hardware <ul><ul><li>ATM </li></ul></ul><ul><ul><ul><li>Result : </li></ul></ul></ul><ul><ul><ul><ul><li>The ATM cell size is a poor choice for voice (packets are too big; bandwidth is wasted) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>The ATM cell size is a poor choice for data (packets are too small; bandwidth is wasted with excessive overhead). </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Welcome to the fascinating world of International Standards! </li></ul></ul></ul></ul>
  64. 75. Summary <ul><li>Configuration, management, and troubleshooting network connections is a major portion of any system administrator’s job. The system administrator needs to: </li></ul><ul><li>Understand basic network terminology. </li></ul><ul><li>Understand the basics of the TCP/IP protocol suite. </li></ul><ul><li>Understand the basics of IP addresses. </li></ul><ul><li>Understand basic IP routing. </li></ul><ul><ul><li>Understand the basics of ARP, and DNS. </li></ul></ul><ul><ul><li>Understand the basics of layer 2 and layer 3 “routing”. </li></ul></ul><ul><li>Understand common network hardware. </li></ul>

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