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IST 201

IST 201. Chapter 9. TCP/IP Model. Application Layer Protocols. FTP TFTP NFS SMTP Telnet Rlogin SNMP DNS HTTP. Transport Layer Protocols. TCP UDP. Internet Layer Protocols. IP ICMP ARP RARP. Network Access. Ethernet Fast Ethernet SLIP & PPP FDDI ATM, Frame Relay, SMDS ARP

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IST 201

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  1. IST 201 Chapter 9

  2. TCP/IP Model

  3. Application Layer Protocols FTP TFTP NFS SMTP Telnet Rlogin SNMP DNS HTTP

  4. Transport Layer Protocols TCP UDP

  5. Internet Layer Protocols IP ICMP ARP RARP

  6. Network Access Ethernet Fast Ethernet SLIP & PPP FDDI ATM, Frame Relay, SMDS ARP Proxy ARP RARP

  7. TCP Segments upper layer application data Sends segments from one end device to another Establishes end to end operations Flow control Reliability – sequence #’s & acknowledgements Error detection & correction

  8. Three-way Handshake SYN ACK ACK Rec’d Has a message to send Sending host/node Receiving host/node TCP three-way handshake to establish a logical communication connection. Communication can begin once the handshake is complete. A three-way handshake is also used to end the connection.

  9. IP • Defines a packet & address scheme • Transfers data between Internet layer and network access • Connectionless

  10. Network Access • Software & drivers for NIC, ISDN & modems • Mapping IP addresses to MAC addresses • Encapsulating packets into frames • Defines the connection with the medium

  11. TCP/IP Model v. OSI Application Presentation Session Transport Network Data Link Physical

  12. TCP/IP & OSI Similarities • Layers • Packet switched

  13. TCP/IP & OSI Differences • TCP/IP Model combines first three layers of OSI • TCP/IP Model combines data link & phys into network access • TCP/IP – simpler • TCP/IP – internet was built based on it • OSI – guide for understanding communication process

  14. Internet Architecture • Getting messages from one network to another requires different approaches than getting messages from one host to another on a LAN • Internetworking – building networks of networks • must be scalable - # networks & computers • transport data vast distances • flexible for technological changes • dynamic • cost effective • anytime, anywhere communication

  15. IANA • Internet Assigned Numbers Authority • organization that assigns network addresses • duplicate public addresses not allowed • organizations may obtain IP network address from an ISP for $

  16. IP Addressing Unique address • IP address for each node must be unique • Four bytes (bytes called octets) • 10.9.19.3 might be a node address • 10.0.0.0 would be the network address • The first 10 in 10.9.19.3 corresponds to the network in this example. • Subnet mask identifies which part of the IP address refers to the network address and which part to the node. • 11111111.00000000.00000000.00000000 (binary subnet mask) • 255.0.0.0 would be the subnet mask

  17. IP Address Classes • Businesses are assigned network IP addresses by IANA depending on the size of the business. • Class A – very large businesses such as the US government • Class B – large businesses • Class C – medium sized businesses

  18. IP Class Addresses and Subnet Masks • The first number of the network address identifies the network class • Class A: 1 – 126 • S/N mask: 255.0.0.0 • Class B: 128 – 191 • S/N mask: 255.255.0.0 • Class C: 192 – 223 • S/N mask: 255.255.255.0 127 used for loopback address (troubleshooting)

  19. Private addresses • 10.0.0.0 • 172.16.0.0 • 192.168.0.0 • May only be used internally.

  20. ICMP • Internet Control Message Protocol • Ping and Tracert are two utilities that use ICMP. • Provides control and error messaging capabilities.

  21. Proposed Solutions to Too Few IPv4 Network Addresses • CIDR (classless interdomain routing) • Single IP address can represent many IP addresses • Example: 172.200.0.0/16 • Private addressing internally • Using NAT (network address translation) to map external public address to internal private addresses • IPv6

  22. Proxy ARP • If a host wants to communicate with a host that is not in the same network, the router can be configured to provide it’s own MAC address if the destination host address is not in the MAC table. • This process allows the message to leave and re-enter the network via the router.

  23. Default Gateway • Configured router interface that is used to communicate with hosts outside the current segment (network). • Router sends it’s own MAC address.

  24. Static v. DHCP Addresses • Static address – manually assigned by the network administrator • DHCP – dynamic host configuration protocol • Dynamically (automatically) assigns IP addresses to hosts on the network for some predetermined amount of time.

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