Download presentation
Presentation is loading. Please wait.
Published byJustina Miles Modified over 9 years ago
1
Data Communication & Computer Networks CS 1652 The slides are adapted from the publisher’s material All material copyright 1996-2009 J.F Kurose and K.W. Ross, All Rights Reserved Jack Lange University of Pittsburgh 1-1
2
Course Objectives Understand modern data communication systems and computer networks Understand the key concepts How they are designed & implemented How they are operated How they are likely to evolve in the future Course Approach Top-down : from what’s familiar to nuts and bolts The Internet as the main focus Hands-on experience on networked systems 1-2
3
Administrativia Instructor: Jack Lange Email: jacklange@cs.pitt.edu Office: Sennott Square #5407 Office Hours: Weds. 2-4PM Teaching Assistant: TBD 1-3
4
Communication Course homepage http://www.cs.pitt.edu/~jacklange/teaching/cs1652-f13/ Announcements, clarifications, corrections Additional resources for projects Google Group http://groups.google.com/group/pitt-cs1652-f13 pitt-cs1652-f13@googlegroups.com Private discussion group Open venue for class discussions and questions Based on email (Pitt addresses) Email me if you want to use a different one
5
TextBooks Computer Networking: A Top-Down Approach James Kurose and Keith Ross Fifth/Sixth Edition, Addison Wesley, 2010 TCP/IP Illustrated, Volume I: The Protocols Richard Stevens Addison Wesley, 1994
6
Class meeting times Lecture Tues/Thurs: 4:00-5:15PM Sennott Square, Rm. 6110 Lab Sessions Sennott Square, Rm. 5506 Periodically replace lectures Hands on exercises Answer project question Hopefully guest lectures 1-6
7
Networking Lab Sennott Square, Rm. 5506 16 Linux machines (Fedore Core 13) Login: Hopefully will be your Pitt login Available for projects Can use other machines, but… Must work on lab equipment Dual NICS 1 internal network interface to be used for projects 1 external network interface for external access 1-11
8
Homework Reading assignments Expected to read before each class Homework 4 problem sets spaced over semester Projects Web server (20%) TCP (50%) Routing (30%) Check Syllabus!
9
Grading Grading Midterm (20%) Final (20%) 4 Homework (10%) 3 Projects (50%) Late policy Submit by midnight of the due date 10% penalty for every day late
10
Projects Work in groups of 2 C/C++ is required Lot of work, but will be worth it Build a TCP stack and a Web server that runs on it IP routing Highly Recommended: OS or having some familiarity with Unix systems programming, preferably in C or C++ Minet is in C++ BUILDING software is 50% of the grade of this class 1-9
11
Today’s topic Computer Networks Overview What’s the Internet? Nuts and bolts vs. service view What’s a protocol? A set of rules between communicating entities Network edge/core Hosts, access networks, physical media Packet switching/circuit switching, Internet structure Goal Get “feel” and terminology More depth, detail later in course 1-12
12
What is the internet? Flows, packets, and bits Optical light, electricity, and radio waves Servers, clients, and peers Hosts, switches, and routers
13
What’s the Internet: Hardware view millions of connected computing devices: hosts = end systems Home network Institutional network Mobile network Global ISP Regional ISP router PC server wireless laptop cellular smartphone wired links access points communication links fiber, copper, radio, satellite transmission rate = bandwidth routers: forward packets (chunks of data) 1-13
14
What’s a protocol? human protocols: “what’s the time?” “I have a question” introductions … specific msgs sent … specific actions taken when msgs received, or other events network protocols: machines rather than humans all communication activity in Internet governed by protocols protocols define format, order of msgs sent and received among network entities, and actions taken on msg transmission, receipt 1-17
15
What’s a protocol? a human protocol and a computer network protocol: Hi Got the time? 2:00 TCP connection response Get http://www.awl.com/kurose-ross time 1-18 TCP connection request
16
Where are we? What’s the Internet? Nuts and bolts vs. service view What’s the protocol? Network edge/core Hosts, access networks, physical media Packet switching/circuit switching, Internet structure 1-19
17
A closer look at network structure: network edge: applications and hosts access networks, physical media: wired, wireless communication links network core: interconnected routers network of networks Edge routers “uplink” to core routers 1-20
18
The network edge: end systems (hosts): run application programs e.g. Web, email at “edge of network” client/server peer-peer client/server model client host requests, receives service from always-on server e.g. Web browser/server; email client/server peer-peer model: minimal (or no) use of dedicated servers e.g. Skype, BitTorrent 1-21 Traditionally where the action is
19
Internet structure: network of networks roughly hierarchical at center: “tier-1” ISPs (e.g., Verizon, Sprint, AT&T, NTT, Quest, Level3, Global Crossing, Tata, Savvis, TeliaSonera), national/international coverage treat each other as equals Tier 1 ISP Tier-1 providers interconnect (peer) privately 1-13
20
Internet structure: network of networks “Tier-2” ISPs: smaller (often regional) ISPs Connect to one or more tier-1 ISPs, possibly other tier-2 ISPs Tier 1 ISP Tier-2 ISP Tier-2 ISP pays tier-1 ISP for connectivity to rest of Internet tier-2 ISP is customer of tier-1 provider Tier-2 ISPs also peer privately with each other. 1-15
21
Internet structure: network of networks “Tier-3” ISPs and local ISPs last hop (“access”) network (closest to end systems) Tier 1 ISP Tier-2 ISP local ISP local ISP local ISP local ISP local ISP Tier 3 ISP local ISP local ISP local ISP Local and tier- 3 ISPs are customers of higher tier ISPs connecting them to rest of Internet 1-16
22
Internet structure: network of networks a packet passes through many networks! Tier 1 ISP Tier-2 ISP local ISP local ISP local ISP local ISP local ISP Tier 3 ISP local ISP local ISP local ISP 1-17
23
Tier-1 ISP: e.g., Sprint … to/from customers peering to/from backbone …. … … … POP: point-of-presence 1-14
24
What’s the Internet: Software-ish view protocols control sending, receiving of msgs e.g., TCP, IP, HTTP, Skype, Ethernet Provides meaning Internet standards RFC: Request for comments IETF: Internet Engineering Task Force Internet: “network of networks” loosely hierarchical public Internet versus private intranet Home network Institutional network Mobile network Global ISP Regional ISP 1-15
25
What’s the Internet: Service view communication infrastructure enables distributed applications: Web, VoIP, email, games, e-commerce, file sharing communication services provided to apps: reliable data delivery from source to destination “best effort” (unreliable) data delivery 1-16
26
Access networks and physical media Q: How to connect end systems to edge router? residential access nets institutional access networks (school, company) mobile access networks Keep in mind: bandwidth (bits per second) of access network? shared or dedicated? 1-22
27
100 Mbps 1 Gbps server Ethernet switch Institutional router To Institution’s ISP Ethernet Internet access Typically used in companies, universities, etc 10 Mbps, 100Mbps, 1Gbps, 10Gbps Ethernet Today, end systems typically connect into Ethernet switch 1-32
28
Wireless access networks shared wireless access network connects end system to router via base station aka “access point” wireless LANs: 802.11b/g (WiFi): 11 or 54 Mbps 802.11n: ~450Mbps wider-area wireless access provided by telco operator ~1Mbps over cellular system (EVDO, HSDPA, 3G) next up: WiMAX (10’s Mbps) over wide area base station mobile hosts router 1-33
29
telephone network DSL modem home PC home phone Internet DSLAM Existing phone line: 0-4KHz phone; 4-50KHz upstream data; 50KHz-1MHz downstream data splitter central office Digital Subscriber Line (DSL) Also uses existing telephone infrastruture up to 1 Mbps upstream up to 8 Mbps downstream dedicated physical line to telephone central office 1-24
30
Residential access: cable modems Diagram: http://www.cabledatacomnews.com/cmic/diagram.html 1-26
31
Cable Network Architecture: Overview home cable headend cable distribution network (simplified) Typically 500 to 5,000 homes 1-27
32
Cable Network Architecture: Overview home cable headend cable distribution network server(s) 1-28
33
Cable Network Architecture: Overview home cable headend cable distribution network (simplified) 1-29
34
Cable Network Architecture: Overview home cable headend cable distribution network Channels VIDEOVIDEO VIDEOVIDEO VIDEOVIDEO VIDEOVIDEO VIDEOVIDEO VIDEOVIDEO DATADATA DATADATA CONTROLCONTROL 1234 56789 FDM (next class): 1-30
35
ONT OLT central office optical splitter ONT optical fiber optical fibers Internet Fiber to the Home (FTTH) Optical links from central office to the home Two competing optical technologies: Passive Optical Network (PON) – e.g. Verizon FIOS Active Optical Network (AON) – Switched Ethernet Much higher Internet rates; fiber also carries television and phone services 1-31
36
Home networks Typical home network components: DSL or cable modem router/firewall/NAT Ethernet wireless access point wireless access point wireless laptops router/ firewall cable modem to/from cable headend Ethernet 1-34
37
Physical media Bit: propagates between transmitter/rcvr pairs physical link: what lies between transmitter & receiver guided media: signals propagate in solid media: copper, fiber, coax unguided media: signals propagate freely, e.g., radio Twisted Pair (TP) two insulated copper wires Category 3: traditional phone wires, 10 Mbps Ethernet Category 5: 100Mbps Ethernet 1-35
38
Physical media: coax, fiber Coaxial cable: two concentric copper conductors bidirectional baseband: single channel on cable Digital signal legacy Ethernet broadband: multiple channels on cable Analog Signal HFC Fiber optic cable: glass fiber carrying light pulses, each pulse a bit high-speed operation: high-speed point-to-point transmission (e.g., 10’s-100’s Gps) low error rate: repeaters spaced far apart ; immune to electromagnetic noise 1-36
39
Physical media: radio signal carried in electromagnetic spectrum no physical “wire” bidirectional propagation environment effects: reflection obstruction by objects interference Radio link types: terrestrial microwave e.g. up to 45 Mbps channels LAN (e.g., Wifi) 11Mbps, 54 Mbps wide-area (e.g., cellular) 3G cellular: ~ 1 Mbps satellite Kbps to 45Mbps channel (or multiple smaller channels) 270 msec end-end delay geosynchronous versus low altitude 1-37
40
Summary 1-38 The Internet can be defined as A set of hosts running distributed applications communicating via routers Infrastructure providing popular services Protocols define the message formats, orders, actions on transmission and reception Access networks: at the network edge Residential (dial-up, DSL, Cable, FTTH) Institutional (Ethernet) Wireless (Wi-fi, WiMAX)
41
Cable modems Does not use telephone infrastructure Instead uses cable TV infrastructure HFC: hybrid fiber coax asymmetric: up to 30Mbps downstream, 2 Mbps upstream network of cable and fiber attaches homes to ISP router homes share access to router unlike DSL, which has dedicated access 1-25
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.