Lecture 4 - The TCPIP Model.pdf

LECTURE 4 THE TCP/IP MODEL OVERVIEW Background to the DoD Model TCP/IP Layer Functions Protocols Ports Addresses BACKGROUND Origins in the DoD ARPANet Popularized through Unix BSD “shareware” and “open source” Replaced other implementation models Novell IPX/SPX Appl...

LECTURE 4 THE TCP/IP MODEL OVERVIEW Background to the DoD Model TCP/IP Layer Functions Protocols Ports Addresses BACKGROUND Origins in the DoD ARPANet Popularized through Unix BSD “shareware” and “open source” Replaced other implementation models Novell IPX/SPX Apple AppleTalk IBM/Microsoft NetBEUI THE 4 LAYERS TCP/IP MODEL OSI MODEL UPPER LAYERS VS LOWER LAYERS The Application Layers is responsible for communication between host applications The Transport, Internet and Network Access Layers are responsible for actual data transmission between hosts PEER LAYERS Logically, layers communicate with their corresponding layers SERVICE LAYERS Physically, layers communicate with their lower layers ENCAPSULATION Sender’s data wrapped with Protocol Data Units (PDUs) by each lower layer at header and occasionally at trailer Each of sender’s layers communicates with corresponding receiver’s layer APPLICATION LAYER FUNCTIONS ENCAPSULATION PROCESS OSI Model’s Application, Protocol Data Unit: Data Presentation and Session Layers (5 – Accepts input from application 7) Encodes, Encrypts and/or Node-to-node application Compresses Data communication and user interface specifications Passes Data to Transport Layer APPLICATION PROTOCOLS WEB SERVICES MAIL SERVICES Hypertext Transfer Protocol (HTTP) Simple Mail Transfer Protocol Hypertext Transfer Protocol Secure (SMTP) (HTTPS) Post Office Protocol (POP) Internet Message Access Protocol (IMAP) APPLICATION PROTOCOLS FILE SERVICES PRINT SERVICES File Transfer Protocol (FTP) Server Message Block (SMB) File Transfer Protocol Secure (FTPS) SSH FTP (SFTP) Trivial File Transfer Protocol (TFTP) Server Message Block (SMB) APPLICATION PROTOCOLS REMOTE ACCESS SERVICES MISCELLANEOUS SERVICES Telnet Dynamic Host Configuration Protocol Secure Shell (SSH) (DHCP) Remote Desktop Protocol (RDP) Domain Name Service (DNS) Network Time Protocol (NTP) Simple Network Management Protocol (SNMP) TRANSPORT LAYER FUNCTIONS ENCAPSULATION PROCESS OSI Model’s Transport Layer (4) Protocol Data Unit: Segment Sequencing and data integrity Accepts Data from Application Layer Uses Port Numbers to keep track of Adds Segment Header simultaneous conversation Passes Segment to Internet Layer Target Ports: well-known port numbers 1023 and below Source Ports: dynamically assigned from 1024 and above TRANSPORT PROTOCOLS TRANSPORT CONTROL PROTOCOL (TCP) USER DATAGRAM PROTOCOL (UDP) Connection-oriented Connectionless Reliable Unreliable Segments data, numbers segments, Segments data without numbering or awaits acknowledgement for the acknowledgement segments Simplex Full-duplex TRANSPORT PROTOCOLS TCP UDP 80: Hypertext Transfer Protocol (HTTP) 443: Hypertext Transfer Protocol Secure (HTTPS) 25: Simple Mail Transfer Protocol (SMTP) 110: Post Office Protocol (POP) 143: Internet Message Access Protocol (IMAP) TRANSPORT PROTOCOLS TCP UDP 20,21: File Transfer Protocol (FTP) 69: Trivial File Transfer Protocol 22: Secure File Transfer Protocol (TFTP) (SFTP) 445: Server Message Block (SMB) TRANSPORT PROTOCOLS TCP UDP 23: Telnet 53: Domain Name Service (DNS) 22: Secure Shell (SSH) 67,68: Dynamic Host Configuration 3389: Remote Desktop Protocol (RDP) Protocol (DHCP) 53: Domain Name Service (DNS) 123: Network Time Protocol (NTP) 161: Simple Network Management Protocol (SNMP) INTERNET LAYER FUNCTIONS ENCAPSULATION PROCESS OSI Model’s Network Layer (3) Protocol Data Unit: Packet Logical Addressing using IP Address Accepts Segment from Transport Layer Routing Adds Packet Header Passes Packet to Network Access Layer INTERNET LAYER PROTOCOLS INTERNET PROTOCOL (IP) looks at each packet’s destination address Internet Control Message Protocol (ICMP): and uses routing table to determine where it is provides hosts with information about network to be sent (network) and how (the best path) problems e.g. destination unreachable or buffer full. Address Resolution Protocol (ARP): finds physical hardware (MAC) address from a Ping uses echo request and reply messages to check physical and logical connectivity of hosts known logical software (IP) address Traceroute uses time-to-live (TTL) time-outs to discover the path packets travel NETWORK ACCESS LAYER FUNCTIONS ENCAPSULATION PROCESS OSI Model’s Physical and Data Link Protocol Data Unit: Frames and Bits Layers (1 – 2) Accepts Packets from Network Layer Hardware addressing (using MAC Adds Frame Header and Trailer Address), topology and physical Passes Bits to Transmission Media transmission NETWORK ACCESS LAYER PROTOCOLS WIRED WIRELESS 802.3: Ethernet (CSMA/CD) 802.11: Wi-Fi (CSMA/CA) 802.4: Token Passing Bus 802.15: Wireless PAN 802.5: Token Passing Ring DECAPSULATION Transport passes Data to Application Internet passes Segment to Transport Network Access passes Packet to Internet Transmission Media passes Bits to Network Access TO BE CONTINUED… LOGICAL ADDRESSING