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 Session 5 Transport 4 Network 3 Data link 2 Physical 1 Media Layers Host Layers

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

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

OSI Reference Model Presents Data / Data Representation Application Presents Data / Data Representation Encryption / Decryption Compression / Decompression Coding / Decoding MPEG, JPEG, RTF, MP3 Presentation Session Transport Network Data-Link Physical

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

OSI Reference Model Setup Communication mode Application Setup Communication mode Reliable and non-reliable communication Segments the data Flow Control Windowing Acknowledgements TCP / UDP PORT Numbers Presentation Session Transport Network Data-Link Physical 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 Logical Addressing Best path selection Application Presentation Logical Addressing Best path selection IP Addressing Data Packets / Route Update Packets Router uses this Layer Session Transport Network Data-Link Physical

Sub Layers of Data-link layer OSI Reference Model Physical Transmission of Data Error Notification Network Topology LLC MAC Application Presentation Session Transport LLC 802.2 Identify Layer 3 Protocol Flow control Sequencing of control bits Network Data-Link Physical Sub Layers of Data-link layer MAC 802.3 Physical addressing How packets placed on media Error notification only Ordered delivery of frames

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

Encapsulation OSI Reference Model Application Data Presentation Session Segment Segment Data Transport Packets Packets Segment Data Network Data-Link Frames Frames Packets Segment Data Physical Bits 0101001010101010000000111110101

Three Layer Model of Cisco Core Layer Distribution Layer Access layer

Three Layer Model of Cisco Core 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 Distribution Layer Access layer

Three Layer Model of Cisco Core 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 Distribution Layer Access layer

Three Layer Model of Cisco Core 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 Distribution Layer Access layer

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

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

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, NetBIOS, SAP, L2TP, PPTP, SOCKS, ASP, SQL Transport: TCP, UDP, SPX Network: IP (v4, v6), ICMP, IPSec, IGMP, IPX, AppleTalk 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