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QSpiders - Upper layer-protocols
- 2. What Is TCP/IP?What Is TCP/IP? • A suite of protocols • Rules that dictate how packets of information are sent across multiple networks • Addressing • Error checking
- 3. TCP/IP ProtocolTCP/IP Protocol • The Transmission Control Protocol/Internet Protocol (TCP/IP) suit was created by the Department of Defense (DoD). • The Internet Protocol can be used to communicate across any set of interconnected networks. • TCP/IP supports both LAN and WAN communications. • IP suite includes not only Layer 3 and 4 specifications but also specifications for common applications like e-mail, remote login, terminal emulation and file transfer. • The TCP/IP protocol stack maps closely to the OSI model in the lower layers.
- 4. The DoD & OSIThe DoD & OSI Application Application Presentation Session Transport Network Data Link Physical Host-to-Host Internet Network Access DoD Model OSI Model
- 5. TCP/IP Protocol SuitTCP/IP Protocol Suit atat DoDDoD DoD Model Process / Application Host-to-Host Internet Network Access TCP/IP Protocol Suit Telnet FTP LPD SNMP X WindowNFSSMTPTFTP TCP UDP ICMP Ethernet ARP RARP IP Fast Ethernet Token Ring FDDI BootP
- 6. TCP/IP ApplicationsTCP/IP Applications • Application layer • File Transfer Protocol (FTP) • Remote Login (Telnet) • E-mail (SMTP) • Transport layer • Transport Control Protocol (TCP) • User Datagram Protocol (UDP) • Network layer • Internet Protocol (IP) • Data link & physical layer • LAN Ethernet, Token Ring, FDDI, etc. • WAN Serial lines, Frame Relay, X.25, etc.
- 7. Internet Layer OverviewInternet Layer Overview • In the OSI reference model, the network layer corresponds to the TCP/IP Internet layer. Internet Protocol (IP) Internet Control Message Protocol (ICMP) Address Resolution Protocol (ARP) Reverse Address Resolution Protocol (RARP) Internet Protocol (IP) Internet Control Message Protocol (ICMP) Address Resolution Protocol (ARP) Reverse Address Resolution Protocol (RARP) Application Transport Internet Data-Link Physical
- 8. Internet ProtocolInternet Protocol • Provides connectionless, best - effort delivery routing of datagrams. • IP is not concerned with the content of the datagrams. • It looks for a way to move the datagrams to their destination.
- 9. IP DatagramIP Datagram Version (4) Destination IP Address (32) Options (0 or 32 if Any) Data (Varies if Any) 1Bit 0 Bit 15 Bit 16 Bit 31 Header Length (4) Type of Service (8) Total Length (16) Identification (16) Flags (3) Fragment Offset (13) Time-to-Live (8) Protocol (8) Header Checksum (16) Source IP Address (32) 20 Bytes
- 10. IP DatagramIP Datagram • Version – Currently used IP version • Header Length – Datagram header length • TOS – Level of importance assigned by a particular upper-layer protocol • Total Length- Length of packet in bytes including Data and Header • Identification – Identifies current datagram (Sequence Number) • Flags – Specifies whether the packet can be fragmented or not • Fragment Offset – Used to piece together datagram fragments •TTL – It maintains a counter that gradually decreases, in increments, to zero • Protocol – It indicates which upper-layer protocol receives incoming packets • Header Checksum – Calculated checksum of the header to check its integrity • Source IP Address – Sending node IP Address • Destination IP Address – Receiving node IP Address • Options – It allows IP to support various options like security • Data – Upper layer information (maximum 64Kb)
- 11. •Determines destination upper-layer protocol Protocol FieldProtocol Field Transport Layer Internet Layer TCP UDP Protocol Numbers IP 176
- 12. Address Resolution ProtocolAddress Resolution Protocol (ARP)(ARP) • ARP works at Internet Layer of DoD Model • It is used to resolve MAC address with the help of a known IP address. • All resolved MAC addresses are maintained in ARP cache table is maintained. • To send a datagram this ARP cache table is checked and if not found then a broadcast is sent along with the IP address. • Machine with that IP address responds and the MAC address is cached.
- 13. Address Resolution ProtocolAddress Resolution Protocol 172.16.3.1 172.16.3.2 IP: 172.16.3.2 = ???IP: 172.16.3.2 = ??? I need the Ethernet address of 176.16.3.2.
- 14. Address Resolution ProtocolAddress Resolution Protocol 172.16.3.1 172.16.3.2 IP: 172.16.3.2 = ???IP: 172.16.3.2 = ??? I heard that broadcast. The message is for me. Here is my Ethernet address. I need the Ethernet address of 176.16.3.2.
- 15. Address Resolution ProtocolAddress Resolution Protocol 172.16.3.1 IP: 172.16.3.2 Ethernet: 0800.0020.1111 IP: 172.16.3.2 Ethernet: 0800.0020.1111 172.16.3.2 IP: 172.16.3.2 = ???IP: 172.16.3.2 = ??? I heard that broadcast. The message is for me. Here is my Ethernet address. I need the Ethernet address of 176.16.3.2.
- 16. Address Resolution ProtocolAddress Resolution Protocol Map IP Ethernet 172.16.3.1 IP: 172.16.3.2 Ethernet: 0800.0020.1111 IP: 172.16.3.2 Ethernet: 0800.0020.1111 172.16.3.2 IP: 172.16.3.2 = ???IP: 172.16.3.2 = ??? I heard that broadcast. The message is for me. Here is my Ethernet address. I need the Ethernet address of 176.16.3.2.
- 17. RARP (Reverse ARP)RARP (Reverse ARP) • This also works at Internet Layer. • It works exactly opposite of ARP • It resolves an IP address with the help of a known MAC addres. • DHCP is the example of an RARP implementation. • Workstations get their IP address from a RARP server or DHCP server with the help of RARP.
- 18. Reverse ARPReverse ARP Ethernet: 0800.0020.1111 IP = ???Ethernet: 0800.0020.1111 IP = ??? What is my IP address?
- 19. Reverse ARPReverse ARP Ethernet: 0800.0020.1111 IP = ???Ethernet: 0800.0020.1111 IP = ??? What is my IP address? I heard that broadcast. Your IP address is 172.16.3.25 .
- 20. Reverse ARPReverse ARP Ethernet: 0800.0020.1111 IP: 172.16.3.25 Ethernet: 0800.0020.1111 IP: 172.16.3.25 Ethernet: 0800.0020.1111 IP = ???Ethernet: 0800.0020.1111 IP = ??? What is my IP address? I heard that broadcast. Your IP address is 172.16.3.25 .
- 21. Reverse ARPReverse ARP •Map Ethernet IP Ethernet: 0800.0020.1111 IP: 172.16.3.25 Ethernet: 0800.0020.1111 IP: 172.16.3.25 Ethernet: 0800.0020.1111 IP = ???Ethernet: 0800.0020.1111 IP = ??? What is my IP address? I heard that broadcast. Your IP address is 172.16.3.25 .
- 22. Bootstrap ProtocolBootstrap Protocol (BootP)(BootP) • BootP stands for BootStrap Protocol. • BootP is used by a diskless machine to learn the following: • Its own IP address • The IP address and host name of a server machine. • The boot filename of a file that is to be loaded into memory and executed at boot- up. • BootP is an old program and is now called the DHCP.
- 23. Bootstrap ProtocolBootstrap Protocol (BootP)(BootP) • BootP stands for BootStrap Protocol. • BootP is used by a diskless machine to learn the following: • Its own IP address • The IP address and host name of a server machine. • The boot filename of a file that is to be loaded into memory and executed at boot-up. • BootP is an old program and is now called the DHCP.
- 24. DHCP (Dynamic Host ConfigurationDHCP (Dynamic Host Configuration Protocol)Protocol) • The DHCP server dynamically assigns IP address to hosts. • All types of Hardware can be used as a DHCP server, even a Cisco Router. • BootP can also send an operating system that a host can boot from. DHCP can not perform this function. • Following information is provided by DHCP while host registers for an IP address: • IP Address • Subnet mask • Domain name • Default gateway (router) • DNS
- 25. Internet Control MessageInternet Control Message ProtocolProtocol Applicatio n Transport Internet Data-Link Physical Destination Unreachable Echo (Ping) Other ICMP 1 •ICMP messages are carried in IP datagrams and used to send error and control messages.
- 27. Transport Layer OverviewTransport Layer Overview Transmission Control Protocol (TCP) User Datagram Protocol (UDP) Transmission Control Protocol (TCP) User Datagram Protocol (UDP) Application Transport Internet Data-Link Physical Connection- Oriented Connectionles s
- 28. Transmission Control ProtocolTransmission Control Protocol (TCP)(TCP) • TCP works at Transport Layer • TCP is a connection oriented protocol. • TCP is responsible for breaking messages into segments and reassembling them. • Supplies a virtual circuit between end-user application.
- 29. TCP Segment FormatTCP Segment Format Source Port (16) Destination Port (16) Sequence Number (32) Header Length (4) Acknowledgment Number (32) Reserved (6)Code Bits (6) Window (16) Checksum (16) Urgent (16) Options (0 or 32 if Any) Data (Varies) 20 Bytes Bit 0 Bit 15 Bit 16 Bit 31
- 30. TCP Segment FormatTCP Segment Format • Source port – Number of the calling port • Destination Port – Number of the called port • Sequence Number – Number used to ensure correct sequencing of the arriving data • Acknowledgement Number – Next expected TCP octet • Header Length – Length of the TCP header • Reserved – Set to zero • Code Bits – Control Functions (setup and termination of a session) • Window – Number of octets that the sender is willing to accept • Checksum – Calculated checksum of the header and data fields • Urgent Pointer – Indication of the end of the urgent data • Options – One option currently defined (maximum TCP segment size) • Data – Upper layer protocol data
- 31. Port NumbersPort Numbers TCP Port Numbers F T P Transport Layer T E L N E T D N S S N M P T F T P S M T P UDP Application Layer 2121 2323 2525 5353 6969 161161 R I P 520520
- 32. TCP Port NumbersTCP Port Numbers Source Port Source Port Destination Port Destination Port …… Host A 10281028 2323 …… SP DP Host Z Telnet Z Destination port = 23. Send packet to my Telnet application.
- 33. Send SYN (seq = 100 ctl = SYN) SYN Received Send SYN, ACK (seq = 300 ack = 101 ctl = syn,ack) Established (seq = 101 ack = 301 ctl = ack) Host A Host B 1 2 3 SYN Received TCP Three-Way Handshake/OpenTCP Three-Way Handshake/Open ConnectionConnection
- 34. • Window Size = 1 Sender Receiver Send 1 Receive 1 Receive ACK 2 Send ACK 2 Send 2 Receive 2 Receive ACK 3 Send ACK 3 Send 3 Receive 3 Receive ACK 4 Send ACK 4 TCP SimpleTCP Simple AcknowledgmentAcknowledgment
- 35. TCP Sequence andTCP Sequence and Acknowledgment NumbersAcknowledgment Numbers Source Port Source Port Destination Port Destination Port …… SequenceSequence AcknowledgmentAcknowledgment 10281028 2323 SourceDest. 11111111 Seq. 22 Ack. 10281028 2323 SourceDest. 10101010 Seq. 11 Ack. 102810282323 SourceDest. 11111111 Seq. 11 Ack. . I just got number 10, now I need number 11. I just sent number 10
- 36. Window Size =3 Send 2 TCP WindowingTCP Windowing Sender Window Size =3 Send 1 Window Size =3 Send 3 ACK 3 Window Size = 2 Packet 3 Is Dropped Window Size =3 Send 4 Window Size =3 Send 3 ACK 5 Window Size = 2 ReceiverWindow Size = 3
- 37. UDP (User DatagramUDP (User Datagram Protocol)Protocol) • A connectionless and unacknowledged protocol. • UDP is also responsible for transmitting messages. • But no checking for segment delivery is provided. • UDP depends on upper layer protocol for reliability. • TCP and UDP uses Port no. to listen to a particular services.
- 38. • No sequence or acknowledgment fields UDP Segment FormatUDP Segment Format Source Port (16) Destination Port (16) Length (16) Data (if Any) 1Bit 0 Bit 15 Bit 16 Bit 31 Checksum (16) 8 Bytes
- 39. UDP Segment FormatUDP Segment Format • Source port – Number of the calling port • Destination Port – Number of the called port • Length – Number of bytes, including header and data • Checksum – Calculated checksum of the header and data fields • Data – Upper layer protocol data
- 40. Application LayerApplication Layer OverviewOverview *Used by the Router Application Transpor t Internet Data- Link Physical File Transfer - TFTP* - FTP* - NFS E-Mail - SMTP Remote Login - Telnet* - rlogin* Network Management - SNMP* Name Management - DNS* File Transfer - TFTP* - FTP* - NFS E-Mail - SMTP Remote Login - Telnet* - rlogin* Network Management - SNMP* Name Management - DNS*
- 41. TelnetTelnet • Telnet is used for Terminal Emulation. • It allows a user sitting on a remote machine to access the resources of another machine. • It allows you to transfer files from one machine to another. • It also allows access to both directories and files. • It uses TCP for data transfer and hence slow but reliable.
- 42. Network File SystemNetwork File System (NFS)(NFS) • It is jewel of protocols specializing in file sharing. • It allows two different types of file systems to interoperate. • This is striped down version of FTP. • It has no directory browsing abilities. • It can only send and receive files. • It uses UDP for data transfer and hence faster but not reliable.
- 43. LPD (Line PrinterLPD (Line Printer Daemon)Daemon) • The Line Printer Protocol is designed for Printer sharing. • The LPD along with the LPR (Line Printer Program) allows print jobs to spooled and sent to the network’s printers using TCP/IP. X Window • X-windows defines a protocol for the writing of graphical user interface-based client/Server application.
- 44. Simple NetworkSimple Network Management ProtocolManagement Protocol • SNMP enable a central management of Network. • Using SNMP an administrator can watch the entire network. • SNMP works with TCP/IP. • IT uses UDP for transportation of the data.
- 45. DNS (Domain NameDNS (Domain Name Service)Service) • DNS resolves FQDNs with IP address. • DNS allows you to use a domain name to specify and IP address. • It maintains a database for IP address and Hostnames. • On every query it checks this database and resolves the IP.
- 46. © 2002, Cisco Systems, Inc. All rights reserved.
- 47. – Unique addressing allows communication between end stations. – Path choice is based on destination address. • Location is represented by an address Introduction to TCP/IPIntroduction to TCP/IP AddressesAddresses 172.18.0.2 172.18.0.1 172.17.0.2172.17.0.1 172.16.0.2 172.16.0.1 SA DA HD R DATA 10.13.0.0 192.168.1.0 10.13.0.1 192.168.1.1
- 48. IPv4 AddressingIPv4 Addressing • 32-bit addresses • Commonly expressed in dotted decimal format (e.g., 192.168.10.12) • Each “dotted decimal” is commonly called an octet (8 bits)
- 49. IP AddressingIP Addressing 255 255 255 255 otted ecimal Maximum Network Host 32 bits
- 50. IP AddressingIP Addressing 255 255 255 255 otted ecimal Maximum Network Host 128 64 32 16 8 4 2 1 1111111111111111 1111111111111111Binary 32 bits 1 8 9 16 17 24 25 32 128 64 32 16 8 4 2 1 128 64 32 16 8 4 2 1 128 64 32 16 8 4 2 1
- 51. IP AddressingIP Addressing 255 255 255 255 Dotted Decimal Maximum Network Host 128 64 32 16 8 4 2 1 1111111111111111 1111111111111111 1010110000010000 0111101011001100 Binary 32 bits 172 16 122 204 Example Decimal Example Binary 1 8 9 16 17 24 25 32 128 64 32 16 8 4 2 1 128 64 32 16 8 4 2 1 128 64 32 16 8 4 2 1
- 52. •Class A: •Class B: •Class C: •Class D: Multicast •Class E: Research IP Address ClassesIP Address Classes NetworkNetwork HostHost HostHost HostHost NetworkNetwork NetworkNetwork HostHost HostHost NetworkNetwork NetworkNetwork NetworkNetwork HostHost 8 bits 8 bits 8 bits 8 bits
- 53. IP Addressing—Class AIP Addressing—Class A • 10.222.135.17 • Network # 10 • Host # 222.135.17 • Range of class A network IDs: 1–126 • Number of available hosts: 16,777,214
- 54. IP Addressing—Class BIP Addressing—Class B • 128.128.141.245 • Network # 128.128 • Host # 141.245 • Range of class B network IDs: 128.1–191.254 • Number of available hosts: 65,534
- 55. IP Addressing—Class CIP Addressing—Class C • 192.150.12.1 • Network # 192.150.12 • Host # 1 • Range of class C network IDs: 192.0.1–223.255.254 • Number of available hosts: 254
- 56. IP Network AddressIP Network Address ClassesClasses 0000000001111111 10111111 1111111111011111 00000000 00000000 11111111 11111111 00000000 00000000 00000000 # Networks 126 16,384 2,097,152 # Hosts 254 65,534 16,777,214 Class A B C Class A 35.0.0.0 Class B 128.5.0.0 Class C 132.33.33.0 Network Address Space Host Address Space Example
- 57. IP Address ClassesIP Address Classes 1 Class A: Bits: 0NNNNNNN0NNNNNNN HostHost HostHost HostHost 8 9 16 17 24 25 32 Range (1-126) 1 Class B: Bits: 10NNNNNN10NNNNNN NetworkNetwork HostHost HostHost 8 9 16 17 24 25 32 Range (128-191) 1 Class C: Bits: 110NNNNN110NNNNN NetworkNetwork NetworkNetwork HostHost 8 9 16 17 2425 32 Range (192-223) 1 Class D: Bits: 1110MMMM1110MMMM Multicast GroupMulticast GroupMulticast GroupMulticast GroupMulticast GroupMulticast Group 8 9 16 17 2425 32 Range (224-239)
- 58. Private AddressesPrivate Addresses • Class A – 10.0.0.0 to 10.255.255.255 • Class B – 172.16.0.0 to 172.31.255.255 • Class C – 192.168.0.0 to 192.168.255.255
- 59. 11111111 Determining Available HostDetermining Available Host AddressesAddresses 172 16 0 0 10101100000100000000000000000000 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 Network Host 0000000000000001 1111111111111111 1111111111111110 ... ... 0000000000000011 11111101 1 2 3 65534 65535 65536 - ... 2 65534 N 2N -2 = 216 -2 = 65534
- 60. Subnet MaskSubnet Mask 172172 1616 00 00 255255 255255 00 00 255255 255255 255255 00 IP Address Default Subnet Mask 8-bit Subnet Mask Network Host Network Host Network Subnet Host Also written as “/16” where 16 represents the number of 1s in the mask. Also written as “/24” where 24 represents the number of 1s in the mask. 11111111 11111111 00000000 00000000
- 61. Decimal Equivalents of BitDecimal Equivalents of Bit PatternsPatterns 1 0 0 0 0 0 0 0 = 128 1 1 0 0 0 0 0 0 = 192 1 1 1 0 0 0 0 0 = 224 1 1 1 1 0 0 0 0 = 240 1 1 1 1 1 0 0 0 = 248 1 1 1 1 1 1 0 0 = 252 1 1 1 1 1 1 1 0 = 254 1 1 1 1 1 1 1 1 = 255 128 64 32 16 8 4 2 1
- 62. 16 Network Host 172 0 0 10101100 11111111 10101100 00010000 11111111 00010000 00000000 00000000 10100000 00000000 00000000 •Subnets not in use—the default 00000010 Subnet Mask withoutSubnet Mask without SubnetsSubnets 172.16.2.160172.16.2.160 255.255.0.0255.255.0.0 Network Number
- 63. •Network number extended by eight bits Subnet Mask with SubnetsSubnet Mask with Subnets 16 Network Host 172.16.2.160172.16.2.160 255.255.255.0255.255.255.0 172 2 0 10101100 11111111 10101100 00010000 11111111 00010000 11111111 00000010 10100000 00000000 00000000 00000010 Subnet Network Number 128 192 224 240 248 252 254 255
- 64. Subnet Mask with SubnetsSubnet Mask with Subnets (cont.)(cont.) Network Host 172.16.2.160172.16.2.160 255.255.255.192255.255.255.192 10101100 11111111 10101100 00010000 11111111 00010000 11111111 00000010 10100000 11000000 10000000 00000010 Subnet •Network number extended by ten bits 16172 2 128 Network Number 128 192 224 240 248 252 254 255 128 192 224 240 248 252 254 255
- 65. Addressing SummaryAddressing Summary ExampleExample 16172 2 160 10101100 00010000 1010000000000010 Host Mask Subnet Broadcast Last First 172.16.2.160 255.255.255.192 4 1
- 66. Addressing SummaryAddressing Summary ExampleExample 10101100 11111111 00010000 11111111 11111111 10100000 11000000 00000010 Host Mask Subnet Broadcast Last First 172.16.2.160 255.255.255.192 1 2 16172 2 160
- 67. Addressing SummaryAddressing Summary ExampleExample 10101100 11111111 00010000 11111111 11111111 10100000 11000000 00000010 Host Mask Subnet Broadcast Last First 172.16.2.160 255.255.255.192 1 2 3 7 16172 2 160
- 68. Addressing Summary ExampleAddressing Summary Example 10101100 11111111 00010000 11111111 11111111 10100000 11000000 10000000 00000010 Host Mask Subnet Broadcast Last First 172.16.2.160 255.255.255.192 1 2 3 4 16172 2 160
- 69. Addressing Summary ExampleAddressing Summary Example 10101100 11111111 00010000 11111111 11111111 10100000 11000000 10000000 00000010 10111111 Host Mask Subnet Broadcast Last First 172.16.2.160 255.255.255.192 1 2 3 4 5 6 16172 2 160
- 70. Addressing SummaryAddressing Summary ExampleExample 10101100 11111111 00010000 11111111 11111111 10100000 11000000 10000000 00000010 10111111 10000001 Host Mask Subnet Broadcast Last First 172.16.2.160 255.255.255.192 1 2 3 4 5 6 16172 2 160
- 71. Addressing SummaryAddressing Summary ExampleExample 10101100 11111111 00010000 11111111 11111111 10100000 11000000 10000000 00000010 10111111 10000001 10111110 Host Mask Subnet Broadcast Last First 172.16.2.160 255.255.255.192 1 2 3 4 5 6 7 16172 2 160
- 72. Addressing SummaryAddressing Summary ExampleExample 10101100 11111111 10101100 00010000 11111111 00010000 11111111 00000010 10100000 11000000 10000000 00000010 10101100 00010000 0000001010111111 10101100 00010000 0000001010000001 10101100 00010000 0000001010111110 Host Mask Subnet Broadcast Last First 172.16.2.160 255.255.255.192 1 2 3 4 5 6 7 8 16172 2 160
- 73. Addressing SummaryAddressing Summary ExampleExample 10101100 11111111 10101100 00010000 11111111 00010000 11111111 00000010 10100000 11000000 10000000 00000010 10101100 00010000 0000001010111111 10101100 00010000 0000001010000001 10101100 00010000 0000001010111110 Host Mask Subnet Broadcast Last First 172.16.2.160 255.255.255.192 172.16.2.128 172.16.2.191 172.16.2.129 172.16.2.190 1 2 3 4 5 6 7 89 16172 2 160
Editor's Notes
- So, what is TCP/IP? TCP/IP is shorthand for a suite of protocols that run on top of IP. IP is the Internet Protocol, and TCP is the most important protocol that runs on top of IP. Any application that can communicate over the Internet is using IP, and these days most internal networks are also based on TCP/IP. Protocols that run on top of IP include: TCP, UDP and ICMP. Most TCP/IP implementations support all three of these protocols. We’ll talk more about them later. Protocols that run underneath IP include: SLIP and PPP. These protocols allow IP to run across telecommunications lines. TCP/IP protocols work together to break data into packets that can be routed efficiently by the network. In addition to the data, packets contain addressing, sequencing, and error checking information. This allows TCP/IP to accurately reconstruct the data at the other end. Here’s an analogy of what TCP/IP does. Say you’re moving across the country. You pack your boxes and put your new address on them. The moving company picks them up, makes a list of the boxes, and ships them across the country using the most efficient route. That might even mean putting different boxes on different trucks. When the boxes arrive at your new home, you check the list to make sure everything has arrived (and in good shape), and then you unpack the boxes and “reassemble” your house.
- Roughly, Ethernet corresponds to both the physical layer and the data link layer. Other media (T1, Frame Relay, ATM, ISDN, analog) and other protocols (SLIP, PPP) are down here as well. Roughly, IP corresponds to the network layer. Roughly, TCP and UDP correspond to the transport layer. TCP is the most important of all the IP protocols. Most Internet applications you can think of use TCP, including: Telnet, HTTP (Web), POP & SMTP (email) and FTP (file transfer).
- Layer 1 of 4: Purpose: This figure shows how ARP is used to determine an IP address. In layer 1, host 172.16.3.1 needs the MAC address of host 172.16.3.2. It sends an ARP request message.
- Layer 2 of 4: In layer 2, host 172.16.3.2 is on the same wire and receives the ARP request message.
- Layer 3 of 4: In layer 3, host 172.16.3.2 sends an ARP reply with its MAC address to host 172.16.3.1.
- Layer 4 of 4: In layer 4, the bulleted items at the bottom of the slide appear. Emphasize: ARP provides translation between network and data link layers. Discuss why it is necessary to have a mechanism like ARP. Describe ARP operation. Not all protocols use ARP. Some use other methods for address translation. Note: For the message to be transmitted uniquely to a single interface on the multiaccess link, it is necessary to build a frame with the unique MAC address of the interface
- Layer 1 of 4: Purpose: This figure explains how RARP works. In layer 1, the host on the left needs its IP address. It sends a RARP request with its MAC address.
- Layer 2 of 4: In layer 2, the host on the right, functioning as a RARP server, maps the MAC address to an IP address.
- Layer 3 of 4: In layer 3, the host on the right sends the IP address to the requester in a RARP reply message.
- Layer 4 of 4: In layer 4, the bulleted items appear at the bottom of the slide. Emphasize: RARP is used to boot diskless workstations over a network.
- Ping is an example of a program that uses ICMP rather than TCP or UDP. Ping sends an ICMP echo request from one system to another, then waits for an ICMP echo reply. It is mostly used for testing.
- Purpose: This slide discuss the initial configurations on the routers and switches. Note: There is no setup mode on the Catalyst 1900 switch.
- Purpose: This slide introduces the startup process on Cisco routers and switches. Emphasize: Paraphrase or restate the three points and make sure your students follow the description. This description is necessary to keep a common perspective of what is occurring on the switch and the router; these three steps should be an anchor to return to as needed. Transition: Where are the sources for configuration software?
- Purpose: This slide describes the different ways students can access the Catalyst switch or Cisco router to create a new configuration file or alter an existing one. Emphasize: The network device can be configured from several locations. After you create the initial configuration, you can configure the ports or interfaces to enable configuration over virtual terminal ports (vty). Both the router and switch support Telnet access as a virtual terminal. The router by default supports virtual terminals 0 through 4. The router can be accessed for configuration purposes from the console port, the auxiliary port, and five VTY lines at the same time—up to seven people can configure the router at once. You should caution students about the above point and inform them that security should be strictly observed through password protection to avoid unauthorized access of the configuration files. Another component important to configuration in the network is a TFTP server. The TFTP server can be a UNIX or PC workstation that acts as a central depository for files. You can keep configuration files on the TFTP server and then download them to the device. You can also configure them from a network management station running network management software such as CWSI, CiscoWorks, or HP OpenView. Before you can access or change the configuration from a virtual terminal, TFTP server, or network management station, you must have the device configured to support IP traffic.
- Purpose: This slide introduces the two Cisco IOS EXEC modes on the Catalyst 1900 switch and routers. Emphasize: As you present this, describe the bullet points that can prepare your students to work with the Cisco IOS user interface.
- Slide 1 of 2 Purpose: This slide describes the user EXEC mode. Emphasize: Present the operational aspects of user EXEC mode. Tell your students that this command level allows them to access only a limited amount of basic monitoring commands. Emphasize that they need to look carefully at the command prompter to make sure that they are in the appropriate mode for the command that they want to enter into the network device. If your class can remember this, this will eliminate (or at least reduce) the number of times that you have to point out that a lab step is failing because the student is in user mode rather than in enabled mode. Transition: An introduction of privileged (or enabled) mode.
- Slide 2 of 2 Purpose: This slide describes the privileged EXEC mode. Emphasize: As you present the introductory material on privileged (also called “enabled”) mode, emphasize that this mode is the entry mode for all other configuration modes. Tell your students that they will need this mode for ICND labs and most of the network administration that they do back on the job. Use the analogy of “the price of admission.” You must enter enable followed by the correct enable password; otherwise, you will not get into the network device; and will have to stay outside in user mode where you can only see a few basic things about the network device. Note: This slide ends the introductory material that is common to the network devices covered in ICND. Transition: Material specific to the initial startup of the Catalyst switch.
- Purpose: This slide discuss the initial configurations on the routers and switches. Note: There is no setup mode on the Catalyst 1900 switch.
- Purpose: This slide introduces Cisco IOS software. Emphasize: Use this slide for your first introduction of Cisco IOS software to your students. Cisco IOS software is the platform that delivers network services for the network applications. This Cisco IOS software platform extends beyond the routers. Cisco IOS also applies to selected Catalyst switches. Eventually, all Cisco platforms may merge to the Cisco IOS software. Note: The Catalyst 1900 and 2900xl switch Cisco IOS has a common look and feel like the router’s Cisco IOS. However, the switch Cisco IOS is not 100 percent identical to the router’s Cisco IOS.
- Most IP addresses today use IP version 4—we’ll talk about IP version 6 later. IPv4 addresses are 32 bits long and are usually written in “dot” notation. An example would be 192.1.1.17. The Internet is actually a lot of small local networks connected together. Part of an IP address identifies which local network, and part of an IP address identifies a specific system or host on that local network. What part of an IP address is for the “network” and what part is for the “host” is determined by the class or the subnet.
- Layer 1 of 3: Purpose: This figure show the general format of an IP address. In layer 1, the address is 32 bits with a network and host portion.
- Layer 3 of 3: In layer 2, one can convert the address to binary.
- Layer 3 of 3: In layer 3, an example of dotted-decimal format and binary are displayed. Emphasize: IP address format is dotted-decimal. Dotted-decimal makes it easy to work with IP addresses. However, in this course we will work with the addresses on the bit level, so we will convert these addresses into binary, make changes to them, and convert them back. The central authority for addresses is the Internet Assigned Numbers Authority. Note: This most common form of addressing reflects the widely used IP version 4. Faced with the problem of depleting available addresses, Internet Engineering Task Force (IETF) work is under way for a backward-compatible next generation of IP (IPng, also called IP 6). IP 6 will offer expanded routing and addressing capabilities with 128-bit addresses rather than the 32-bit addressing shown on the graphic. Addresses from both IP versions will coexist. Initial occurrences will probably be at locations with address translator software and firewalls.
- Purpose: This graphic describes the three most common classes of IP address. Emphasize: Discuss classes of addresses. Each address contains information about the network number and the host number of the device. Class A addresses are for very large organizations. Class B addresses are for smaller organizations, and Class C addresses for even smaller ones. As the number of networks grows, classes may eventually be replaced by another addressing mechanism, such as classless interdomain routing (CIDR). RFC 1467, Status of CIDR Deployment in the Internet, presents information about CIDR. RFC 1817, CIDR and Classful Routing, also presents CIDR information.
- Here’s an example of a class A address. Any IPv4 address in which the first octet is less than 128 is by definition a class A address. This address is for host #222.135.17 on network #10, although the host is always referred to by its full address: 10.222.135.17.
- Here’s an example of a class B address. Any IPv4 address in which the first octet is between 128 and 191 is by definition a class B address.
- Here’s an example of a class C address. Most IPv4 addresses in which the first octet is 192 or higher are class C addresses, but some of the higher ranges are reserved for multicast applications.
- To summarize: IPv4 addresses are 32 bits with a network part and a host part. Unless you are using subnets, you divide an IP address into the network and host parts based on the address class. The network part of an address is used for routing packets over the Internet. The host part is used for final delivery on the local net.
- Emphasize: Highlight the fixed values that start each class address. The first octet rule states that when an address falls into a specified range, it belongs to a certain class. Students should soon be able to recognize the address class of any IP address on sight. Note: If time or interest permits, you can use the initial bit patterns in the first octet and show how a class of IP network derives the range of network numbers for that IP address class.
- Purpose: This figure explains how to calculate the number of available hosts in a network. Emphasize: 2N-2 is the calculation to determine available hosts. N is the number of binary digits in the host field. Subtract 2 because a host cannot be all 0s or 1s. The same principal applies when determining the number of available networks.
- Emphasize: Turn on more bits to represent subnets. Compare the default or standard subnet mask with the subnet mask in the slide. These are the rules for IP addressing: An address is 32 bits, divided into three components: First octet rule bits Network bits (path selection bits) Node bits The first octet rule states that the most significant bit pattern in the first octet determines the class of the address. Path selection bits cannot be all ones or zeros. Certain addresses are reserved. RFC 1918 defines some of those. Prefix or mask one bits are path selection significant; zero bits are host bits and therefore not significant. Use the logical AND to combine the address and mask bits to get the subnet address. The maximum number of available subnets equals 2 prefix bits - 2; the maximum number of available hosts equals 2 32- prefix bits - 2.
- Purpose: This figure explains how subnet masks are converted to decimal addresses. Emphasize: Review binary-to-decimal conversion, bit weighting, and conversion. Explain logical AND. One possible explanation of logical AND follows: We will need to be able to perform a logical AND on the binary numbers. Just take two binary numbers and place one above the other. The ones in the bottom are like a pipe—the number above it just drops through. The zeros are like a clogged pipe, so nothing comes out in the answer. Presenting a truth table will help some students understand. You might need to give more than one explanation. Note: You might want to hand out a binary-to-decimal conversion sheet if you have not already done so. We have not included one in the lab section. It is more useful to have one that is on a separate page from the labs.
- Purpose: This graphic explains how routers use addresses that have no subnet mask. Emphasize: Explain how masking works at the bit level. Zero bits mask host information. Note: This is an easy place to lose students. At this point, they need to learn several abstract mathematical concepts before we can show them how to lay out an IP-addressed network. To the novice these techniques may seem unrelated, making the presentation confusing. To a more experienced audience, these techniques will be familiar.
- Purpose: This figure shows how the router determines an address when subnetting is used. Emphasize: This example makes a Class B address space look like a collection of Class C address spaces. Now the logical AND allows us to extract the subnet number as well as the assigned network number. An exercise follows that tests the students’ understanding of subnet masks.
- Purpose: This figure shows how the router determines an address when subnetting is used. Emphasize: This example is different from the previous example in that the the subnet and host are divided within an octet. Transition: An exercise follows that tests the students’ understanding of subnet masks.
- Layer 1 of 9: Purpose: This example summarizes The IP addressing that was covered earlier in this chapter. Emphasize: In layer 1, convert the address to a binary host address.
- Layer 2 of 9: Emphasize: In layer 2, write the subnet mask in binary.
- Layer 3 of 9: Emphasize: In layer 3, draw a line after the recursive ones in the subnet mask.
- Layer 4 of 9: Emphasize: In layer 4, fill in zeros beyond the vertical line for the subnet.
- Layer 5 of 9: Emphasize: In layer 5, fill in ones beyond the vertical line for the broadcast address.
- Layer 6 of 9: Emphasize: In layer 6, fill in 0s beyond the vertical line except for the last bit. Make that bit a 1. This is the first usable host address.
- Layer 7 of 9: Emphasize: In layer 7, fill in 1s beyond the vertical line except for the last bit. Make that bit a 0. This is the last usable host address.
- Layer 8 of 9: Emphasize: In layer 8, copy the binary network and subnetwork address from the top row into the lower rows.
- Layer 9 of 9: Emphasize: In layer 9, convert binary back to dotted decimal.