Binit Mohanty Ketan Rajawat Networks Binit Mohanty Ketan Rajawat

Recap – Layered Architecture Application layer for GUI Transport layer for Reliability Networking layer for routing MAC layer for Media access control Physical layer for modulation

Ethernet Used in IITK LAN One medium - many users IP address and Names - the DNS server CSMA/CD – Carrier Sense Multiple Access with Collision Detection

Internetworking Eg: Connecting many LANs Each Network has Routers Routers run some programs for finding the best path Data in form of packets appended with source and destination address Forwarded according to routing table

TCP – Transport Layer Limitations of PHY layer Solution : TCP Packets are lost, reordered, duplicated Congestion, overflow Solution : TCP Reliability by ACKs Numbering of packets Limit transfer rate according to congestion

TCP : Connection Establishment Called a connection oriented protocol as opposed to a best effort protocol

TCP : Slow Start

TCP : Close Connection

TCP When would one not want TCP ? When would reliability be at a lower priority ? Streaming Data – streaming video Energy efficiency – Sensor Networks

GSM – Global System for Mobile

GSM – channels Channels comprising of frequencies and time slots Broadcast channel – network identity, frequency of operation Control Channels –signal power, channel estimate, timing estimate, call origination Traffic channels for voice