Chapter 2 - Page 1 Infogem Institute of Technology CCNA Course TCP/IP Protocol Suite TCP/IP PROTOCOL SUITE Chapter 3 Sybex, Chapter 9 Exam Cram

Chapter 2 - Page 2 Infogem Institute of Technology CCNA Course TCP/IP Protocol Suite TOPICS The TCP/IP and DOD Reference Model Process/Application Layer Protocols Host-to-Host Layer Protocols Internet Layer Protocols Network Access Layer Protocols IP Address Resolution Local Resolution The ARP Cache Remote Resolution

Chapter 2 - Page 3 Infogem Institute of Technology CCNA Course TCP/IP Protocol Suite THE DOD REFERENCE MODEL Late 60’s – Department of Defense Process/ Application Host-to-Host Internet Network Access Application Presentation Session Transport Network Data Link Physical THE DOD REFERENCE MODEL AND TCP/IP 4 LAYER MODEL Process/ Application Transport Internet Network Access Telnet TCP IP Ethernet FTP Fast Ethernet LPD UDP Token Ring SNMP FDDI TFTPSMTPNFSX window ICMPBootPARPRARP Application Host-to-Host Network Interface

Chapter 2 - Page 4 Infogem Institute of Technology CCNA Course TCP/IP Protocol Suite PROCESS/APPLICATION LAYER PROTOCOLS Address the ability of one application to communicate with another, regardless of hardware platform, operating system, and other features of the two hosts Most applications written with TCP/IP protocols can be characterized as client/server applications –Searches for information –Printing – –Application services –File transfers PROCESS/APPLICATION LAYER PROTOCOLS Telnet -Terminal emulation FTP - (File Transfer Protocol) File transfer TFTP- (Trivial File Transfer Protocol) Stripped-down version of FTP SMTP - (Simple Mail Transfer Protocol) Uses a queued method of mail delivery -Delivery Only LPD - (Line Printer Daemon) Designed for printer sharing -UNIX SNMP - (Simple Network Management Protocol) Provides performance histories of the network NFS - (Network File Systems) Specializing in file sharing -Sun Microsystems X window - Defines a protocol for writing GUI-based client/server applications -UNIX – Windows Emulation Process/ Application TelnetFTPLPDSNMP TFTPSMTPNFSX window APPLICATION PRESENTATION SESSION

Chapter 2 - Page 5 Infogem Institute of Technology CCNA Course TCP/IP Protocol Suite TRANSPORT LAYER PROTOCOL Main purpose is to shield the upper-layer applications from the complexities of the network TCP – Connection-oriented, reliable protocol, Guaranteed Delivery –Segmentation –Error checking –Windowing –Slower UDP – Connectionless, unreliable protocol, No guaranteed Delivery –Segmentation –Send and Forget –Faster Host-to-HostTCP Fed EX UDP Canada Post TCP (TRANSMISSION CONTROL PROTOCOL) TCP segments the data stream received from the upper layers and prepares it for the network layer TCP guarantees delivery using ACK Source Port Destination Port Sequence Number Ack Number WindowData

Chapter 2 - Page 6 Infogem Institute of Technology CCNA Course TCP/IP Protocol Suite PORT NUMBERS Port Numbers are used to keep track of different conversations crossing the network simultaneously RFC 1700 discusses the well-known port Numbers are used for public applications Numbers 256 – 1023 are assigned to companies to use in their applications Numbers below 1024 are considered well known. Numbers above 1024 – 64k are used by the upper layer applications to set up sessions with other host PORT NUMBERS FTP also uses port 20 for receiving data Port 80 – WWW, HTTP TCPUDP FTPTelnetSMTPDNSTFTPSNMP Port Numbers Send 6 17

Chapter 2 - Page 7 Infogem Institute of Technology CCNA Course TCP/IP Protocol Suite UDP (USER DATAGRAM PROTOCOL) UDP is the scaled down version of TCO, AKA thin protocol UDP is a connectionless, unreliable protocol It does not acknowledge or sequence segments, not does it create a virtual circuit Source Port Destination Port LengthChecksumData UDP Segment Format

Chapter 2 - Page 8 Infogem Institute of Technology CCNA Course TCP/IP Protocol Suite NETWORK LAYER PROTOCOLS Two main reasons for the Internet layer’s existence: –Routing –Providing a single network interface to the upper layers NETWORK (INTERNET) LAYER PROTOCOLS IP – receives segments from the Host-to-Host layer and fragments them into packets (Datagrams). Route Selection ICMP – management protocol and messaging service provider for IP. PING, TRACE or (tracert). BootP – used by a workstation to discover its IP address. DHCP ARP – used to map an IP address (have) to a MAC address (need). Address Resolution Protocol RARP – provides a method for finding IP addresses (need) based on MAC addresses (have) Reverse Address Resolution Protocol Internet IP ICMPBootPARPRARP

Chapter 2 - Page 9 Infogem Institute of Technology CCNA Course TCP/IP Protocol Suite IP (NETWORK PROTOCOL) Protocol identifies either TCP (6) or UDP (17) Internet Control Message Protocol (ICMP) ICMP is a management protocol and messaging service for IP. Some common events and messages that ICMP relates to: –Ping – Packet internet groper uses ICMP echo messages to check the connectivity of computers on a network. –Destination Unreachable – If a router can not send an IP datagram any further it uses ICMP to send a message back to sender. –Traceroute – Using ICMP timeouts, traceroute is used to find the path a packet takes through a network. –Buffer Full – if a router’s buffer is full, it will use ICMP to send out this message. Version Frag Offset TTLProtocol Source IP Address Destination IP Address Data

Chapter 2 - Page 10 Infogem Institute of Technology CCNA Course TCP/IP Protocol Suite ICMP TESTING Ping Command generates these results Ping Command generates an ICMP unreachable or timeout condition ICMP Echo Request ICMP Echo Reply Is Y Reachable? Yes, I’m Reachable. X Y ICMP TESTING Destination unreachable Host or port unreachable Network unreachable Destination Unreachable To A Send data to A I don’t know how to get to A Send ICMP Reply

Chapter 2 - Page 11 Infogem Institute of Technology CCNA Course TCP/IP Protocol Suite DATA LINK (NETWORK ACCESS) LAYER PROTOCOLS Receiving an IP datagram and framing it into a stream of bits for physical transmission Placing the MAC address into the frame Error Checking (CRC) Specifying access method: Contention, token passing, polling Specifying the physical media, connectors, electrical signaling and timing rules Network Access Ethernet Fast Ethernet Token RingFDDI

Chapter 2 - Page 12 Infogem Institute of Technology CCNA Course TCP/IP Protocol Suite LOGICAL & PHYSICAL ADDRESSING Physical (hardware)(MAC) addressing is a unique address that is burned into each NIC by the manufacturer –48 bits expressed in 6 bytes 3 bytes for the Organizational Unique Identifier 3 bytes for the serial number of the card –Organization Identifier is assigned by IEEE Logical Addressing or Virtual addressing contains both network and host address –IP address: Four octets –IPX address: c bit address, 32 bit for network & 48 bit Mac or host. –AppleTalk address:

Chapter 2 - Page 13 Infogem Institute of Technology CCNA Course TCP/IP Protocol Suite IP ADDRESS RESOLUTION - LOCAL IP address resolution is the linking of an IP address to a hardware address. ARP is responsible for IP address to Physical address association Local Resolution 1)Is the destination IP on the local network? (Route (default gateway) or short (broadcast) –If yes, check cache 2)If not in cache, send broadcast requesting the MAC address 3)The reply message is sent directly to the hardware address of the requesting machine 4)Upon receipt, the requesting machine will add the address to its ARP cache

Chapter 2 - Page 14 Infogem Institute of Technology CCNA Course TCP/IP Protocol Suite IP ADDRESS RESOLUTION - REMOTE Remote Resolution 1.Is the destination IP on the local network? –If no, … 2.Send broadcast requesting the MAC of Default Gateway (router) 3.The source host will use IMCP to issue an echo request back to the router but addressed to the destination host 4.The destination host will respond to the ARP request with an ARP reply ARP - ADDRESS RESOLUTION PROTOCOL Resolve MAC address from IP address I want the MAC address of This broadcast is for me. Here is my MAC address Source IP: Source MAC: Dest. IP: Dest. MAC: ffff.ffff.ffff Source IP: Source MAC: Dest. IP: Dest. MAC: XY

Chapter 2 - Page 15 Infogem Institute of Technology CCNA Course TCP/IP Protocol Suite THE ARP CACHE ARP cache is a table used to store both IP addresses and their corresponding MAC addresses Old ARP entries are released early when the ARP cache becomes full Router# show arp –Displays the contents of arp cache REVERSE ARP Resolve IP address from MAC address What is my IP Address? I understand the broadcast. Your IP address is Ethernet: IP: Ethernet: IP: