Networking - chapter 1 - How it works, Summaries of Wireless Networking

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Networking

Chapter 1 Introduction

Chapter 1

Introduction

Computer Networking: A

Top-Down Approach

8 th^ edition Jim Kurose, Keith Ross Pearson, 2020

Internet

The Internet: a “nuts and bolts” view mobile network home network enterprise network national or global ISP local or regional ISP datacenter network content provider network Packet switches : forward packets (chunks of data) ▪ routers , switches Communication links ▪ fiber, copper, radio, satellite ▪ transmission rate: bandwidth Billions of connected computing devices : ▪ hosts = end systems ▪ running network apps at Internet’s “edge” Networks ▪ collection of devices, routers, links: managed by an organization

“Fun” Internet-connected devices IP picture frame Web-enabled toaster + weather forecaster Internet phones Internet refrigerator Slingbox: remote control cable TV Tweet-a-watt: monitor energy use sensorized, bed mattress Security Camera Amazon Echo Pacemaker & Monitor Others? Fitbit AR devices

▪ Infrastructure that provides

services to applications:

• Web, streaming video, multimedia teleconferencing, email, games, e- commerce, social media, inter- connected appliances, … The Internet: a “service” view mobile network home network enterprise network national or global ISP local or regional ISP datacenter network content provider HTTP network Skype Streaming video

▪ provides programming interface

to distributed applications:

• “hooks” allowing sending/receiving apps to “connect” to, use Internet transport service
• provides service options, analogous to postal service

What’s a protocol? Human protocols: ▪ “what’s the time?” ▪ “I have a question” ▪ introductions … specific messages sent … specific actions taken when message received, or other events Network protocols: ▪ computers (devices) rather than humans ▪ all communication activity in Internet governed by protocols

Protocols define the format, order of

messages sent and received among

network entities, and actions taken

on msg transmission, receipt

Chapter 1: roadmap ▪ What is the Internet? ▪ What is a protocol? ▪ Network edge: hosts, access network, physical media ▪ Network core: packet/circuit switching, internet structure ▪ Performance: loss, delay, throughput ▪ Security ▪ Protocol layers, service models ▪ History

A closer look at Internet structure mobile network home network enterprise network national or global ISP local or regional ISP datacenter network content provider network Network edge:

▪ hosts: clients and servers

▪ servers often in data centers

A closer look at Internet structure Network edge:

▪ hosts: clients and servers

▪ servers often in data centers

Access networks, physical media:

▪wired, wireless communication links

Network core:

▪ interconnected routers

▪ network of networks

mobile network home network enterprise network national or global ISP local or regional ISP datacenter network content provider network

Access networks and physical media mobile network home network enterprise network national or global ISP local or regional ISP datacenter network content provider network Q: How to connect end systems to edge router? ▪ residential access nets ▪ institutional access networks (school, company) ▪ mobile access networks (WiFi, 4G/5G) What to look for: ▪ transmission rate (bits per second) of access network? ▪ shared or dedicated access among users?

Access networks: cable-based access cable modem splitter

cable headend data, TV transmitted at different frequencies over shared cable distribution network

▪ HFC: hybrid fiber coax

• asymmetric: up to 40 Mbps – 1.2 Gbs downstream transmission rate, 30-100 Mbps upstream transmission rate

▪ network of cable, fiber attaches homes to ISP router

• homes share access network to cable headend cable modem termination system CMTS ISP

ISP Access networks: digital subscriber line (DSL) central office (^) telephone network DSLAM voice, data transmitted at different frequencies over dedicated line to central office ▪ use existing telephone line to central office DSLAM

• data over DSL phone line goes to Internet
• voice over DSL phone line goes to telephone net ▪ 24 - 52 Mbps dedicated downstream transmission rate ▪ 3.5-16 Mbps dedicated upstream transmission rate DSL modem splitter DSL access multiplexer

Wireless access networks

Shared wireless access network connects end system to router

▪ via base station aka “access point”

Wireless local area networks

(WLANs) ▪ typically within or around building (~100 ft) ▪ 802.11b/g/n (WiFi): 11, 54, 450 Mbps transmission rate to Internet to Internet

Wide-area cellular access networks

▪ provided by mobile, cellular network operator (10’s km) ▪ 10’s Mbps ▪ 4G cellular networks (5G coming)

Access networks: enterprise networks

▪ companies, universities, etc.

▪ mix of wired, wireless link technologies, connecting a mix of switches

and routers (we’ll cover differences shortly)

▪ Ethernet: wired access at 100Mbps, 1Gbps, 10Gbps

▪ WiFi: wireless access points at 11, 54, 450 Mbps

Ethernet switch institutional mail, web servers institutional router Enterprise link to ISP (Internet)