6.1. Introduction

LANs: • Bus or ring topology • Each packet is sent to all terminals. • By evaluation of destination address: Destination terminal reads packet, other terminals ignore it. • No routing function needed; unique addressing scheme is sufficient. LANs interconnected by bridges: • Stupid bridge (promiscuous mode): Copy all packets from on LAN to the other respecting the (possibly different) medium access schemes. • Self-learning bridge: Observe traffic in both LANs, to learn addresses of terminals located on either side. Copy packets only to other LAN, if destination terminal located there or if its location is unknown. Tasks in routing: 1) Gathering information on the network (terminals, switches, and their interconnections). 2) Search a route for a connection or a datagram. 3) Controlling the switching matrix; i.e. execution of the packet forwarding from an incoming line to the correct outgoing line (to the next node towards the packet's destination). Examples: 1) Information about network (graph)