Multiplexing Need to share network resources How? Switched network Party Agets resources sometimes Party"B" gets them sometimes Interior nodes act as“ Routers”or atches" baten mechanisTasuGaerskan@dun@sources? 13/87
Introduct by Weifeng Sun Computer network-Introduction 13/87 Multiplexing! • Need to share network resources • How? Switched network – Party “A” gets resources sometimes – Party “B” gets them sometimes • Interior nodes act as “Routers” or “Switches” • What mechanisms can share resources?
Packet Switching (our emphasi Source sends information as self-contained ackets that have an address Source may have to break up single message in multiple Each packet travels independently to the destination host Routers and switches use the address in the packet to determine how to forward the packets Analogy: a letter in surface mail luct by Weifeng Sun ompueretwork-Introd 4/87
Introduct by Weifeng Sun Computer network-Introduction 14/87 Packet Switching (our emphasis) • Source sends information as self-contained packets that have an address. – Source may have to break up single message in multiple • Each packet travels independently to the destination host. – Routers and switches use the address in the packet to determine how to forward the packets • Analogy: a letter in surface mail
Chapter 1: Introduction Overviews Our goal: what's the Internet get " feel"and what's a protocol? terminology more depth neTwork edge detail later in network core course access net, physical medid approach: Internet/isP structure use Internet as. performance: loss, delay example protocol layers, service models erfeng Computer I帕她中 worucrrodeling15/87
Introduct by Weifeng Sun Computer network-Introduction 15/87 Chapter 1: Introduction Our goal: • get “feel” and terminology • more depth, detail later in course • approach: – use Internet as example Overview: • what’s the Internet • what’s a protocol? • network edge • network core • access net, physical media • Internet/ISP structure • performance: loss, delay • protocol layers, service models • network modeling
Chapter 1: roadmap 1.1 What is the Internet? 1.2 Network edge end systems, access networks, links 1.3 Network core a circuit switching, packet switching, network structure 1.4 Delay, loss and throughput in packet-switched networks 1.5 Protocol layers, service models 1.6 Networks under attack: securi story erfeng Computer network-Introduction 16/87
Introduct by Weifeng Sun Computer network-Introduction 16/87 Chapter 1: roadmap 1.1 What is the Internet? 1.2 Network edge ❑ end systems, access networks, links 1.3 Network core ❑ circuit switching, packet switching, network structure 1.4 Delay, loss and throughput in packet-switched networks 1.5 Protocol layers, service models 1.6 Networks under attack: security 1.7 History
The internet An inter-net: a network of networks A set of networks that are connected with each other Networks are connected using routers that support communication in a hierarchical fashion Often need other special devices at the boundaries for security, accounting The Internet: the interconnected set of networks of the Internet Service Providers(isps) providing data communications services About 17,000 different networks make up the Internet In order to inter-operate, all participating networks have to follow a common set of rules erfeng Computer network-Introduction 17/87
Introduct by Weifeng Sun Computer network-Introduction 17/87 “The Internet” • An inter-net: a network of networks. – A set of networks that are connected with each other – Networks are connected using routers that support communication in a hierarchical fashion – Often need other special devices at the boundaries for security, accounting, .. • The Internet: the interconnected set of networks of the Internet Service Providers (ISPs) providing data communications services. – About 17,000 different networks make up the Internet • In order to inter-operate, all participating networks have to follow a common set of rules