A packet switch consists of a routing engine(table look-up), a switch scheduler, and a switch fabric. The routing engine looks-up the packet address in a routing table and determines which output port to send the packet. Packet is tagged with port number The switch uses the tag to send the packet to the proper output port Eytan Modiano

Broadcast Routing Route a packet from a source to all nodes in the network Possible solutions: Flooding: Each node sends packet on all outgoing links Discard packets received a second time Spanning Tree Routing: Send packet along a tree that includes all of the nodes in the network

RESERVATION SYSTEMS Single channel shared by multiple users Only one user can use the channel at a time Need to coordinate transmissions between users Polling systems Polling station polls the users in order Polling to see if they have something to send station A scheduler ca

Queueing Systems Used for analyzing network performance In packet networks, events are random Random packet arrivals Random packet lengths While at the physical layer we were concerned with bit-error-rate, at the network layer we care about delays How long does a packet spend waiting in buffers

Automatic Repeat ReQuest(ARQ) When the receiver detects errors in a packet, how does it let the transmitter know to re-send the corresponding packet? Systems which automatically request the retransmission of missing packets or packets with errors are called ARQ systems Three common schemes Stop Wait

Computer Science 6.111-Introductory Digital Sy Laborator How to Make Your 6.1ll Project Work There are a few tricks of the trade \which allow an experienced digital designer to fix problems quickly. This note is an attempt to fill you in on some with which you might not

Massachusetts Institute of Technology Department of Electrical Engineering and Computer Science 6.111-Introdi igital Systems Labo Report guide Introduction The purpose of this memorandum is to describe general requirements for the reports you

Massachusetts Institute of Technology Department of Electrical Engineering and Computer Science 6. 111-Introductory Digital Systems Laboratory Project suggestions In past years, a great variety of projects have been successfully completed. The following is a list of some of these completed final project reports

1土地信息系统建设概述 2可行性研究 3系统需求分析 4土地信息系统设计 5土地信息系统测试 6土地信息系统数据库建立与维护 7土地信息系统评价

第五章空间分析(Spatial Analysis) 第一节空间查询与量算 第二节空间数据的统计分析 第三节空间分析