OSI Reference Model Kashif Ishaq OSI Reference Model

OSI Reference Model Kashif Ishaq

OSI Reference Model • Application 7 • Presentation 6 • Session 5 • Transport 4 • Network 3 • Data link 2 • Physical 1

OSI Reference Model • Application 7 • Presentation 6 Host Layers • Session 5 • Transport 4 • Network 3 • Data link 2 • Physical 1 Media Layers

PDU Protocol Data Unit OSI Reference Model • Application 7 • Presentation 6 Software Layers • Session 5 • Transport 4 • Network 3 • Data link 2 • Physical 1 Hardware Layers Devices resides

OSI Reference Model Application All applications runs on this layer Presentation Session Transport Network Data-Link Physical • • • Web applications Chat applications DNS FTP TFTP HTTP File and Print Services Massagers Web Browsers

OSI Reference Model Application Presentation Session Transport • Presents Data / Data Representation • Encryption / Decryption • Compression / Decompression • Coding / Decoding Network Data-Link Physical • MPEG, JPEG, RTF, MP 3

OSI Reference Model Application • Logical Sessions between Application Presentation Session Transport Network Data-Link Physical • Create • Stay • Terminate • Keeps different applications data separate form one another • ASP, Net. BIOS, Half/Full Duplex, RTP, SIP

OSI Reference Model Application Presentation Session Transport Network Data-Link Physical • • Setup Communication mode Reliable and non-reliable communication Segments the data Flow Control Windowing Acknowledgements TCP / UDP PORT Numbers A port number is part of the addressing information used to identify the senders and receivers of messages. Port numbers are most commonly used with TCP/IP connections

OSI Reference Model Application Presentation Session Transport Network Data-Link Physical • • • Logical Addressing Best path selection IP Addressing Data Packets / Route Update Packets Router uses this Layer

OSI Reference Model Presentation Session Transport Network Data-Link Physical • • • Physical Transmission of Data Error Notification Network Topology LLC MAC Sub Layers of Data-link layer Application LLC 802. 2 Identify Layer 3 Protocol Flow control Sequencing of control bits MAC 802. 3 Physical addressing How packets placed on media Error notification only Ordered delivery of frames

OSI Reference Model Application Presentation Session Transport Network Data-Link Physical • • • Physical Media Related Bits Hubs Repeaters DCE - DTE

OSI Reference Model Encapsulation Application Presentation Data Session Transport Segment Data Network Packets Segment Data Frames Data-Link Packets Segment Data Physical Bits 01010101010000000111110101

Three Layer Model of Cisco Core Layer Distribution Layer Access layer

Three Layer Model of Cisco Core Layer Distribution Layer Access layer Core of the Network Responsible for transporting large amount of traffic All users can affect by failure of this layer Low Latency Technologies… FDDI ATM FAST ETHERNET GIGABIT ETHERNET Redundant Links Available on this layer

Three Layer Model of Cisco Core Layer Distribution Layer Access layer Known as Workgroup Layer Communication point between Access and Core Layer Features includes… Packet Filtering ACL Policies on the Network Security Policies Address Translation Firewalls Redistributing between Routing Protocols Intern VLAN Routing Broadcast and Multicast Domains

Three Layer Model of Cisco Core Layer Distribution Layer Access layer Control users and workgroups access to internetwork resources Knows as Desktop layer Ethernet Switching Static Routing Workgroup connectivity into distribution layer Separate the Collision Domains

Data Transmission Application Presentation Session Application data Application Data representation Presentation Session management Session Reliable / non-reliable Transport Network Data-Link Physical Port numbers Logical addresses Route Physical address Media conversion Transport Network Data-Link Physical

Transport Layer End-to-End data transport services on different manners TCP Three Way Handshaking Acknowledgment Windowing Sequencing Sync-Ack

Transport Layer End-to-End data transport services on different manners TCP Three Way Handshaking Acknowledgment Windowing Sequencing

Transport Layer End-to-End data transport services on different manners TCP Three Way Handshaking Acknowledgment Windowing Sequencing

Transport Layer End-to-End data transport services on different manners TCP Three Way Handshaking Acknowledgment Windowing Sequence numbers Packet identification for layer Retransmit and Acknowledgement

OSI REFERENCE MODEL WITH THE REFERENCE OF PROTOCOLS Application: NNTP, SIP, DNS, FTP, HTTP, NFS, NTP, SMTP, SNMP, Telnet, DHCP, RTP Presentation: TLS, SSL Session: Named PIPE, Net. BIOS, SAP, L 2 TP, PPTP, SOCKS, ASP, SQL Transport: TCP, UDP, SPX Network: IP (v 4, v 6), ICMP, IPSec, IGMP, IPX, Apple. Talk Data link: ATM, SDLC, HDLC, ARP, SLIP, 802. 3, Frame Relay, PPP, X. 25, Switching Protocols Physical: DSL, 802. 3, 802. 5, 802. 11, 802. 16, IEEE 1394, SONET, POTS, OTN, USB, Bluetooth, Hubs