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Hands-on Networking Fundamentals

Hands-on Networking Fundamentals. Chapter 3 Using Network Communication Protocols. An Overview of Network Protocols. Protocols enable effortless interchange Analogize protocols to dialects Computer communication requires common protocol Human communication requires common dialect

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Hands-on Networking Fundamentals

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  1. Hands-on Networking Fundamentals Chapter 3 Using Network Communication Protocols

  2. An Overview of Network Protocols • Protocols enable effortless interchange • Analogize protocols to dialects • Computer communication requires common protocol • Human communication requires common dialect • LANs may transport multiple protocols • Network device (such as router) makes distinctions • Example: Ethernet hosts TCP/IP for Windows server, AppleTalk for Macintosh computer • Pros and cons of hosting multiple protocols • Pro: networks perform many different functions on LAN • Con: volume of network traffic increases Hands-on Networking Fundamentals

  3. Hands-on Networking Fundamentals

  4. Properties of a LAN Protocol • Capabilities included in properties of LAN protocol • Enable reliable network links • Communicate at relatively high speeds • Handle source and destination node addressing • Follow standards, particularly the IEEE 802 standards • Protocols have different strengths and drawbacks • Example 1: some (not all) protocols are routable • Example 2: some protocols have poor error checking • Protocols typically used on LANs • IPX/SPX, NetBEUI, AppleTalk, and TCP/IP • TCP is most widely used due to relation to Internet Hands-on Networking Fundamentals

  5. Understanding IPX/SPX • Internetwork Packet Exchange (IPX) • Developed by Novell for NetWare operating system • NetWare used with Ethernet bus, token ring, ARCnet • Modeled after Xerox Network System (XNS) protocol • Sequenced Packet Exchange (SPX) • Companion protocol to IPX • Developed for use with applications, such as databases • IPX/SPX used on NetWare servers through version 4 • TCP/IP is preferred protocol for NetWare 6 and above • New NetWare versions can still implement IPX/SPX Hands-on Networking Fundamentals

  6. Hands-on Networking Fundamentals

  7. Activity 3-1: Configuring NWLink in Windows XP • Time Required: Approximately 5 minutes • Objective: Configure a Windows XP client to access NetWare using NWLink (similar for Windows Server 2003). • Description: Configure Windows XP to use Client Service for NetWare and NWLink for accessing an older NetWare server. Log on to Windows XP using an account that has Administrator privileges. Hands-on Networking Fundamentals

  8. The History and Role of TCP/IP • Advanced Research Projects Agency (ARPA) • Networking goal: enable university, research, and Defense Department to communicate • ARPANET WAN: prototype for modern networks • An early protocol: Network Control Protocol (NCP) • Enabled DEC, IBM, and other hosts to communicate • Did not provide wholly reliable communication • TCP/IP combination: an improvement over NCP • TCP (Transmission Control Protocol) • IP (Internet Protocol) • TCP/IP has become most widely used protocol suite Hands-on Networking Fundamentals

  9. The History and Role of TCP/IP (continued) • Five advantages of TCP/IP • Used worldwide on most networks and the Internet • Influences design of wide range of network devices • Main protocol of most computer operating systems • Subject to many troubleshooting and network analysis tools • Understood by large body of network professionals • TCP/IP associated with a suite of protocols and applications • Associations enable TCP/IP to underlie vast range of communications capabilities Hands-on Networking Fundamentals

  10. Hands-on Networking Fundamentals

  11. Understanding TCP/IP • TCP specified in RFC 793 • Designed for point-to-point communications • IP specified in RFC 791 • Developed to link nodes in different networks or WANs • TCP and IP first combined for use with UNIX • TCP/IP layers may be roughly mapped to OSI layers • Core components of TCP/IP protocol suite • Transmission Control Protocol (TCP) • User Datagram Protocol (UDP) • Internet Protocol (IP) Hands-on Networking Fundamentals

  12. How Transmission Control Protocol Works • TCP is a transport protocol (Layer 4 in OSI model) • Establishes sessions between network nodes • Sequences and acknowledges frames • Provides for reliable end-to-end delivery • Sequence number placed in TCP frame header • Shows frame sequence in stream of frames • Indicates amount of data in frames • Sequence number checked for frame correctness • Sliding window: number of data bytes in frame • May be dynamically adjusted if two nodes agree Hands-on Networking Fundamentals

  13. How Transmission Control Protocol Works (continued) • Main TCP functions (similar in OSI Transport layer) • Monitor for session requests • Establish sessions with other TCP nodes • Transmit and receive data • Close transmission sessions • TCP ports: used to form virtual circuit between nodes • Enable multiple processes to communicate in session • TCP segment: header and data payload in TCP frame • TCP header contains 11 fields • Minimum length is 20 bytes Hands-on Networking Fundamentals

  14. Hands-on Networking Fundamentals

  15. Hands-on Networking Fundamentals

  16. How the User Datagram Protocol (UDP) Works • User Datagram Protocol (UDP) • Connectionless protocol • Operates at OSI Layer 4 (like TCP) • Alternative to TCP when high reliability not required • Frame has four-field header and data • Relies only on checksum to ensure reliability • Connectionless protocol • No flow control, sequencing, or acknowledgment • Advantages: adds little overhead onto IP • Used with transaction processing applications • Carries important network status messages Hands-on Networking Fundamentals

  17. Hands-on Networking Fundamentals

  18. How the Internet Protocol (IP) Works • A LAN may be composed of series of subnetworks • A WAN may comprise series of autonomous networks • Examples: DSL, SONET, X.25, and ISDN • Communications enabled by Internet Protocol (IP) • Between different subnetworks on a LAN • Between different networks on a WAN • Network transport options should be compatible with TCP/IP • Transport options include: Ethernet, token ring, X.25, FDDI, ISDN, DSL, frame relay, ATM Hands-on Networking Fundamentals

  19. How the Internet Protocol (IP) Works (continued) • Basic IP Functions: data transfer, packet addressing, packet routing, fragmentation, detection of errors • Addressing essential for data transfer and routing • 32-bit network node address used with 48-bit MAC address • Connectionless protocol • Provides network-to-network addressing and routing information • Changes packet size when size varies with network • Datagram: TCP segment formatted with IP header • IP packet header consists of thirteen fields Hands-on Networking Fundamentals

  20. Hands-on Networking Fundamentals

  21. How IP Addressing Works • IP addressing used to identify two entities • Specific node • Network on which node resides • Unique IP address enables accurate packet delivery • Two nodes with same IP address create error • IP addressing concepts fundamental in networking Hands-on Networking Fundamentals

  22. Basic IP Addressing • Dotted decimal notation: IP address format • Four fields totaling 32 bits • Fields are decimal values representing 8-bit binary octets • Part of address is network ID, part is host ID • Example in decimal format: 129.5.10.100 • Five IP address classes, Class A through Class E • Address reflects network size and transmission type • Three types of transmission • Unicast: packet sent to each requesting client • Multicast: packet sent to group of requesting clients • Broadcast: communication sent to all network nodes Hands-on Networking Fundamentals

  23. Hands-on Networking Fundamentals

  24. The Role of the Subnet Mask • TCP/IP requires configured subnet mask • Subnet mask used for two purposes • Show class of addressing used • Divide networks into subnetworks to control traffic • Example of a subnet mask: • 11111111.00000000.00000000.00000000 (255.0.0.0) • Indicates Class A network • Ones represent network/subnet identification bits • Zeroes represent host identification bits Hands-on Networking Fundamentals

  25. Creating Subnetworks • Subnet mask contains subnet ID • Subnet ID contained within network and host IDs • Subnet ID determined by network administrator • Ex: 11111111.11111111.11111111.00000000 (255.255.255.0) • Third octet in Class B address indicates subnet ID • Subnet mask overrides four-octet length limitation • Classless Interdomain Routing (CIDR) addressing • Puts a slash ( / ) after the dotted decimal notation • Number after slash represents bits in network ID • Example (decimal): 165.100.18.44/18 • 18 bits needed for network ID, 14 for host ID (32 -18) Hands-on Networking Fundamentals

  26. IP Address Rules • Network number 127.0.0.0 cannot be assigned • Address used for diagnostic purposes • Certain IP network numbers reserved as private • No one can use private addresses on Internet • Designed for use behind NAT device; e.g., firewall • May be used on private network with NAT device • Network number cannot be assigned • Highest number on a network cannot be assigned • Address interpreted as broadcast message for subnet • Example: cannot assign 198.92.4.255 Hands-on Networking Fundamentals

  27. Activity 3-5: View the IP Address and Subnet Mask Configuration in Windows XP and Windows Server 2003 • Time Required: Approximately 5 minutes • Objective: View and learn where to configure IP addressing information in Windows XP and Windows Server 2003 • Description: This activity enables you to view where to set up the IP address and subnet mask in Windows XP Professional or Windows Server 2003. Hands-on Networking Fundamentals

  28. The Promise of IPv6 • IPv6 developed through IETF initiative • IPv6 overcomes limitations of IPv4 • Networks are beginning to transition to IPv6 • Five prominent features of IPv6 • 128-bit address capability • Single address associated with multiple interfaces • Address autoconfiguration and CIDR addressing • 40-byte header instead of IPv4’s 20-byte header • New IP extension headers for special needs • Includes more routing and security options Hands-on Networking Fundamentals

  29. The Promise of IPv6 (continued) • Three IPv6 packet types: unicast, anycast, multicast • DES (Data Encryption Standard) • Network symmetric-key encryption standard • IPv6 supports DES compatible encryption techniques • Benefits of IPv6 encryption capability • Security over Internet • Security over other types of LANs and WANs • Disadvantage of IPv6 encryption capability • Increases latency of network communications • Latency: travel time from sending node to receiving node Hands-on Networking Fundamentals

  30. TCP/IP Application Protocols • Useful protocols and applications in TCP/IP suite • Telnet • Secure Shell (SSH) • FileTransfer Protocol (FTP), Trivial FileTransfer Protocol (TFTP), and Network File System (NFS) • Simple Mail Transfer Protocol (SMTP) • Domain Name System (DNS) • Dynamic Host Configuration Protocol (DHCP) • Address Resolution Protocol (ARP) • Simple Network Management Protocol (SNMP) • Hypertext Transfer Protocol (HTTP), Secure Hypertext Transfer Protocol (S-HTTP), HTTP Secure (HTTPS) Hands-on Networking Fundamentals

  31. Telnet • Telnet: application protocol for terminal emulation • Terminal: device with a monitor and keyboard • Examples: IBM 3270 or DEC VT220 • Terminal emulation: Computer behaving like terminal • User access resources in a remote host • Example: Telnet with 3270 emulator connects to IBM mainframe like terminal • Important Telnet features • Comes with nearly all implementations of TCP/IP • Open standard • A number of communications options Hands-on Networking Fundamentals

  32. SSH • Secure Shell (SSH) • Provides authentication security for TCP/IP applications • Used on many UNIX/Linux systems and in MAC OS X • Circumstances for using SSH (if available) • Remotely accessing a computer • Uploading and downloading files • How to start SSH application • Enter ssh at the UNIX/Linux command line • Learning about system dependent implementation • Use the man ssh command in Linux and Mac OS X Hands-on Networking Fundamentals

  33. File Transfer Protocol (FTP), Trivial File Transfer Protocol (TFTP), and Network File System (NFS) • FTP: allows transfer of data between remote devices • Transmissions may be binary or ASCII formatted files • Transmissions ensured by connection-oriented service • Limitation of FTP: cannot transfer portion of file • TFTP: intended for transfer of small files • Use for non-critical and non-secure transmissions • Connectionless protocol running UDP instead of TCP • NFS: Sun Microsystem's alternative to FTP • Uses connection-oriented protocol running in TCP Hands-on Networking Fundamentals

  34. Simple Mail Transfer Protocol (SMTP) • Designed for exchange of electronic mail • Two implementations • For e-mail exchange between networked systems • In local e-mail systems for Internet transport • Provides alternative to FTP for file transfer • Limited to sending text files • Requires e-mail address on receiving end • Does not require logon ID and password • Two part message: address header and message text • Supported in TCP by connection-oriented service Hands-on Networking Fundamentals

  35. Domain Name System (DNS) • Domain: logical grouping of network resources • Domains given unique names; e.g., Microsoft.com • DNS resolves domain names • Resolution: converts domain name to IP address • Internet host domain names have two to three parts • Top-level domain name (TLD): organization or country • Optional subdomain name: university/business name • Host name: name of computer • Example: myname@myorganization.com • ICANN coordinates and registers root domain names Hands-on Networking Fundamentals

  36. Hands-on Networking Fundamentals

  37. Domain Name System (DNS) (continued) • Namespace: logical area with list of named objects • Zones: partitions in DNS server with resource records • Forward lookup zonelinks computer name to IP address • Reverse lookup zone links IP address to computer name • Three servers related to DNS • Primary DNS server: authoritative server for zone • Secondary DNS server: backup servers • Root servers: find TLDs on the Internet • Two DNS standards • Service resource record (SRV RR) • DNS dynamic update protocol Hands-on Networking Fundamentals

  38. Dynamic Host Configuration Protocol (DHCP) • Enables automatic assignment of IP address • Process of assigning address by DHCP server • Newly configured computer contacts DHCP server • DHCP server leases an IP address to new computer • Lease length set on DHCP server by network admin • Server or host may be given lease that does not expire • IP address will never change with permanent lease Hands-on Networking Fundamentals

  39. Address Resolution Protocol (ARP) • Enables sender to retrieve MAC address • Process of obtaining MAC address • Sending node sends ARP broadcast frame • Frame has MAC address, IP address of recipient • Receiving node sends back its MAC address • Reverse Address Resolution Protocol (RARP) • Used by network node to determine its IP address • Used by applications to determine IP address of workstation or server Hands-on Networking Fundamentals

  40. Simple Network Management Protocol (SNMP) • Enables steady monitoring of network activity • Advantages • Operates independently on the network • Management functions carried out on special node • Has low memory overhead • Node types: network management station (NMS) and network agents • SNMPv2 offers better security, error handling, multiprotocol support, transmissions • SNMP and SNMPv2 monitor LANs and WANS Hands-on Networking Fundamentals

  41. Activity 3-8: Configuring an SNMP Agent • Time Required : Approximately 15 minutes • Objective: Learn to make Windows XP an SNMP agent. • Description: Windows XP can be configured to act as an SNMP agent for a network management station. In this project, you learn how to install SNMP in Windows XP. Hands-on Networking Fundamentals

  42. HTTP, S-HTTP, and HTTPS • Hypertext Transfer Protocol (HTTP) • Enables establishment of a Web connection • Provides for exchange of resources • Example: displaying Web page in browser • Secure Hypertext Transfer Protocol (S-HTTP) • Used primarily in native HTTP communications • Does not encrypt data in IP-level communications • Hypertext Transfer Protocol Secure (HTTPS) • Uses Secure Sockets Layer to implement security • More common than S-HTTP Hands-on Networking Fundamentals

  43. TCP and the OSI Reference Model Compared • Portions of TCP moving closer to OSI model • Physical layer: TCP supports coaxial, twisted-pair, fiber-optic, wireless communication • Data Link layer: TCP compatible with IEEE 802.2 LLC and MAC addressing • Network layer: TCP/IP equivalent is IP • Transport layer: both TCP and UDP operate here • Upper layers of OSI correspond to TCP/IP applications Hands-on Networking Fundamentals

  44. Hands-on Networking Fundamentals

  45. Transporting LAN Protocols Over WANs • WAN protocols enable transport from LANs to WANs • Serial Line Internet Protocol (SLIP) • Encapsulates TCP/IP during connection session • TCP/IP removed from SLIP after data payload received • Compressed Serial Line Internet Protocol (CSLIP) • Newly developed extension of SLIP • Compresses header in each packet sent across link • SLIP and CSLIP do not support • Network connection authentication • Setup of connections at multiple layers • Synchronous connections Hands-on Networking Fundamentals

  46. Transporting LAN Protocols Over WANs (continued) • Point-to-Point Protocol (PPP) • Supports more network protocols than SLIP • Automatically sets up connections with several layers • Supports connection authentication and encryption • Point-to-Point Tunneling Protocol (PPTP) • Supplements PPP • Enables remote communications via the Internet • PPTP and PPP support synchronous communication • PPTP and PPP support Password Authentication Protocol (PAP) Hands-on Networking Fundamentals

  47. Transporting LAN Protocols Over WANs (continued) • Layer Two Tunneling Protocol (L2TP) • Similar to PPTP, and like PPTP used on VPNs • Like PPTP, L2TP encapsulates PPP • Creates special tunnels over public network (Internet) • Uses Layer Two Forwarding (based on MAC addresses) • Signaling System 7 (SS7) • For fast communications between different type WANS • Supports call roaming, voicemail, redirection of 800 calls • Adapted for T-carrier and other WAN communications Hands-on Networking Fundamentals

  48. Designing A Network To Use TCP/IP And Application Protocols • Scenario: network personnel in medical office • Seven major components in network design • Workstations and servers configured for TCP/IP • Automatic (DHCP-based) IP addressing used • DHCP used to lease IP addresses to workstations • All servers given permanent IP addresses • SNMP used in certain stations for network monitoring • Network browsers set up to use PPP for Internet links • Workstations set up to use FTP/HTTP through firewalls • E-mail system configured to employ SMTP • Primary DNS server and secondary DNS server set up Hands-on Networking Fundamentals

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