CS 350 Chapter-2

Advantages layered Model

Please Do Not Throw Sausage Pizza Away Application Provides a user interface Presentation Presents data, handles processing such as data encryption, compression Session Keeps different applications’ data separate (simplex, half duplex, and full duplex) Transport Provides reliable or unreliable delivery, performs error correction before retransmit (Conn-oriented, flow control) Network Provides logical addressing, which routers use for path determination Data Link Combines packets into bytes and bytes into frames, provides access to media using MAC address, performs error detection not correction Physical Moves bits between devices, specifies voltage, wire speed, and pin-out of cables

Transport Connection-Oriented Communication Windowing Acknoledgement Virtual circuit Sequencing Acknowledgement Flow control Windowing Acknoledgement

Networking Data packets Route-update packets Network address Interface Metric

Routers Do not forward broadcast or multicast Use IP address to forward packet to the next hop Use access list, created by admin, to control security on the types of packets allowed to enter or exit Can provide layer-2 bridging functions, and route through the same interface simultaneously Layer-3 device, provide connection between VLAN Provide QoS

The Data Link Layer Media Access Control (MAC) Contention media access – first come first serve Logical Link Control (LLC) Encapsulation Flow control Sequencing

IEEE 802 – LAN/MANs 802.2 --- LLC 802.3 --- CSMA/CD 802.11 – Wireless LAN 802.16 -- WiMAX

Physical Layer Bit patterns Encoding bits Interfaces Physical topology

Encapsulation