Internetworking and ATM Lecture 8, April 30, 2003 Data Communications and Networks Mr. Greg Vogl Uganda Martyrs University

April 30, 2003 Data Communications and Networks: Lecture 8: Internetworking and ATM2 Overview Internetworking IU A247 Lectures 4, 5 Hodson Ch. 11 BITDCO Lectures 16, 17 ATM IU A247 Lecture 14 Hodson Ch. 10 BITDCO Lectures 23, 24

April 30, 2003 Data Communications and Networks: Lecture 8: Internetworking and ATM3 Uses of Interconnection Devices Partition an existing network or isolate a server For security and performance Combine existing isolated networks For communication and consistency Create a backbone or hierarchy For organisation, ease of future expansion Connect a network to a larger network

April 30, 2003 Data Communications and Networks: Lecture 8: Internetworking and ATM4 Internetworking and the OSI Model

April 30, 2003 Data Communications and Networks: Lecture 8: Internetworking and ATM5 Repeater Simplest device, OSI physical level Repeats and increases the signal Extends range of a IEEE LAN Operates at same speed as the LAN Retiming, reconstructs preamble Auto-partition to isolate faulty segments Local, fibre, multi-port, or mixed media

April 30, 2003 Data Communications and Networks: Lecture 8: Internetworking and ATM6 Bridge Connects different types of 802 LANs Works at MAC level (lower Data Link layer) Connects distant LANs; extends range Can connect LANs to a backbone Stores and forwards; buffering No flow control; delays; buffer overflow Filters traffic; pass only non-local traffic Improves security, performance of LANs

April 30, 2003 Data Communications and Networks: Lecture 8: Internetworking and ATM7 Mechanics of a Bridge Each port has unique hardware address Each port has a table to store addresses Records sender and receiver addresses Packets only sent if not on local LAN Translates frames to different protocols Arranges, removes fields; recalculates CRC Stand-by bridge provides alternate path Spanning tree algorithm finds, cuts loops

April 30, 2003 Data Communications and Networks: Lecture 8: Internetworking and ATM8 Router Works at network layer of OSI model Interconnects two or more networks Administered separately may be very far apart Intelligently filters data by user or type Provides security e.g. acts as a firewall Provides network management info e.g. Simple Network Management Protocol

April 30, 2003 Data Communications and Networks: Lecture 8: Internetworking and ATM9 Mechanics of a Router Has an Internet address Constant, assigned by administrator Handles 1 or more address protocols e.g. IP (TCP/IP), IPX (IPX/SPX, Novell) Uses a dynamic routing protocol e.g. Routing Information Protocol (RIP) Stores network addresses in routing tables Delivers packets to next network segment

April 30, 2003 Data Communications and Networks: Lecture 8: Internetworking and ATM10 Other Devices Brouter A device that can act as a bridge or router Used in multiple-protocol networks Gateway A device to connect networks Works at higher levels of protocol stack Combination of hardware and software

April 30, 2003 Data Communications and Networks: Lecture 8: Internetworking and ATM11 X.25 An old public network run by telecomms Implemented internationally, up to 64 kbps Connection-oriented (virtual circuit) Establish call, transfer data, disconnect Addressing, routing, multiplexing At network layer Packet assembly/disassembly standards X.3 PAD device, X.28 commands for DTE

April 30, 2003 Data Communications and Networks: Lecture 8: Internetworking and ATM12 Frame Relay Another public network technology Derived from ISDN, used in B-ISDN 64 kbps to 2 Mbps, can also carry voice Permanent virtual circuits Data Link Connections have IDs Statistical multiplexing in data link layer Higher level layers handle errors

April 30, 2003 Data Communications and Networks: Lecture 8: Internetworking and ATM13 Fibre Distributed Data Interface Double ring of fibre optic cable Similar to token bus and token ring Primary, secondary rings Fault tolerance; self healing Provides backbone capability Connect with concentrators and bridges 100 Mbps, 2km between active nodes 4 bit/5 bit encoding

April 30, 2003 Data Communications and Networks: Lecture 8: Internetworking and ATM14 ATM: Asynchronous Transfer Mode Fast (155, 622 and 1200 Mbit/s) Efficient, lightweight Constant, scaleable bandwidth per user Seamlessly interconnects LANs, WANs Devices connect ATM switches to existing LANs Can emulate LAN connections Useful for data, voice, audio, images, video Used for high-speed direct server connection Used to create network backbone

April 30, 2003 Data Communications and Networks: Lecture 8: Internetworking and ATM15 ATM Switching Packet switching based on B-ISDN Not circuit switching like ISDN Asynchronous like a modem Hardware is synchronous Error handling at end points No overhead in the packet itself

April 30, 2003 Data Communications and Networks: Lecture 8: Internetworking and ATM16 ATM Implementation Cells: small packets with low overhead 5 byte header + 48 byte data = 53 bytes Request quality of service metrics Peak/min cell rates, delay, loss ratio etc. Establish uni-directional virtual circuit Using dynamic routing Transfer data cells in correct order Using the virtual circuit

April 30, 2003 Data Communications and Networks: Lecture 8: Internetworking and ATM17 ATM Switches Use shared memory Buffer/queue for two simultaneous inputs Routing table at each input port Traffic management Congestion control Admission control Resource reservation Rate-based control

April 30, 2003 Data Communications and Networks: Lecture 8: Internetworking and ATM18

April 30, 2003 Data Communications and Networks: Lecture 8: Internetworking and ATM19 ATM Cell Format Generic Flow Control Protocol Connection ID Virtual Path ID Virtual Channel ID Payload Type ID Cell Loss Priority Header Error Correction (CRC) Data (“payload”)