Presentation is loading. Please wait.

Presentation is loading. Please wait.

02 - Switches and Access Introduction.

Published byGregory Arnold Modified over 6 years ago

Similar presentations

Presentation on theme: "02 - Switches and Access Introduction."— Presentation transcript:

1 02 - Switches and Access Introduction

2 Chapter 1 Introduction A note on the use of these ppt slides:
We’re making these slides freely available to all (faculty, students, readers). They’re in PowerPoint form so you can add, modify, and delete slides (including this one) and slide content to suit your needs. They obviously represent a lot of work on our part. In return for use, we only ask the following: If you use these slides (e.g., in a class) in substantially unaltered form, that you mention their source (after all, we’d like people to use our book!) If you post any slides in substantially unaltered form on a www site, that you note that they are adapted from (or perhaps identical to) our slides, and note our copyright of this material. Thanks and enjoy! JFK/KWR All material copyright J.F Kurose and K.W. Ross, All Rights Reserved Computer Networking: A Top Down Approach Featuring the Internet, 5rd edition. Jim Kurose, Keith Ross Addison-Wesley, July 2010.

3 The Network Core mesh of interconnected routers
the fundamental question: how is data transferred through net? circuit switching: dedicated circuit per call: telephone net packet-switching: data sent thru net in discrete “chunks”

4 Network Core: Circuit Switching
End-end resources reserved for “call” link bandwidth, switch capacity dedicated resources circuit-like (guaranteed) performance call setup required

5 Network Core: Circuit Switching
network resources (e.g., bandwidth) divided into “pieces” pieces allocated to calls resource piece idle if not used by owning call (no lending) dividing link bandwidth into “pieces” Frequency Division Multiplexing (FDM) Time Division Multiplexing (TDM)

6 Circuit Switching: FDM and TDM
4 users Example: FDM frequency time TDM frequency time Two simple multiple access control techniques. FCC and European Radio-communications committee FDM: Each user uses a circuit and gets a share of the bandwidth. TDM: Each user/circuit gets the full bandwidth periodically, during brief intervals. A number of forums and standards bodies work on standards for frequency allocation, including: International Telecommunication Union (ITU) European Conference of Postal and Telecommunications Administrations (CEPT) European Telecommunications Standards Institute (ETSI) International Special Committee on Radio Interference (Comité international spécial des perturbations radioélectriques - CISPR) Each mobile’s share of the bandwidth is divided into portions for the uplink and the downlink. Also, possibly, out of band signaling. As we will see, used in AMPS, GSM, IS-54/136

7 Packet Switching: Statistical Multiplexing
10 Mbs Ethernet C A statistical multiplexing 1.5 Mbs B queue of packets waiting for output link D E Statistical multiplexing - The link sharing is adapted to the instantaneous traffic demands of the data streams that are transferred over each channel. Sequence of A & B packets does not have fixed pattern  statistical multiplexing. (In TDM each host would get same slot in revolving TDM frame.)

8 Network Core: Packet Switching
each end-end data stream divided into packets Packets from different users share network resources each packet uses full link bandwidth resources used as needed resource contention: aggregate resource demand can exceed amount available congestion: packets queue, wait for link use store and forward: packet must be completely received before being forwarded packet loss: drop a packet from the queue, when too many packets Bandwidth division into “pieces” Dedicated allocation Resource reservation

9 Packet switching versus circuit switching
Is packet switching a “slam dunk winner?” Great for bursty data resource sharing simpler, no call setup Does not restrict the number of simultaneous users Takes advantage of “silent periods” of users Excessive congestion: packet delay and loss protocols needed for reliable data transfer, congestion control

10 Packet-switched networks: forwarding
Goal: move packets through routers from source to destination we’ll study several path selection (i.e. routing)algorithms (chapter 4) datagram network (Internet): destination address in packet determines next hop routes may change during session analogies: USPostal mail, asking directions when driving virtual circuit network (X.25, frame relay, ATM): each packet carries tag (virtual circuit ID), tag determines next hop fixed path determined at call setup time, remains fixed thru call routers maintain per-call state

11 Network Taxonomy Telephones Internet Telecommunication networks
Circuit-switched networks FDM TDM Packet-switched networks Networks with VCs Datagram Telephones Internet

12 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 Introduction

13 Residential access: point to point access
Dialup via modem up to 56Kbps direct access to router (often less) Can’t surf and phone at same time: can’t be “always on” ADSL: Asymmetric Digital Subscriber Line up to 1 Mbps upstream up to 8 Mbps downstream FDM: Dial-up modem converts the digital signals from the comp to analog signals that are transmitted in the 0-4 KHz range (of voice signals). Copper wires are capable of transmitting much wider range of frequencies. DSL exploits that. Your telephone may not support DSL, if: There are amplifying coils along the path (for the voice signals). They distort the DSL signals. There are bridges The distance is too much – signals fade Fiber-optic cables along the path as the DSL signals cannot be converted to digital and back. Introduction

14 Residential access: cable modems
HFC: Hybrid Fiber Coax asymmetric: up to 1Mbps upstream, 10 Mbps downstream network of cable and fiber attaches homes to ISP router shared access to router among homes deployment: available via cable companies. Introduction

15 Cable Network Architecture: Overview
Typically 500 to 5,000 homes A cable television head end is a master facility for receiving television signals for processing and distribution over a cable television system. cable headend home cable distribution network (simplified) Introduction

16 Cable Network Architecture: Overview
cable headend home cable distribution network (simplified) Introduction

17 Cable Network Architecture: Overview
server(s) A cable television head end is a master facility for receiving television signals for processing and distribution over a cable television system. cable headend home cable distribution network Introduction

18 Cable Network Architecture: Overview
FDM: Channels V I D E O A T C N R L 1 2 3 4 5 6 7 8 9 cable headend home cable distribution network Introduction

19 Company access: local area networks
company/univ Local Area Network (LAN) connects end system to edge router Ethernet: shared or dedicated link connects end system and router 10 Mbs, 100Mbps, Gigabit Ethernet deployment: institutions, home LANs happening now LANs: chapter 5 Introduction

20 Wireless access networks
shared wireless access network connects end system to router via base station aka “access point” wireless LANs: 802.11b (WiFi): 11 Mbps base station mobile hosts router Based on IEEE technology. 802.11ac: under development (single link with have throughput of at least 500 Mbits/s. Introduction

21 Internet structure: network of networks
roughly hierarchical at center: “tier-1” ISPs (e.g. Sprint, AT&T, UUNet, Level3), national/international coverage treat each other as equals NAP Tier-1 providers interconnect at public Network Access Points (NAPs) Tier 1 ISP Early 80s, NSF developed NSFNet i.e. decided to make the Internet hierarchical and then privatize it. It also introduced 4 NAPS that basically had all top-tiers connect to them. This way the Tier 1 ISPs could communicate with any other ISP through the NAP. NAP  Major Internet interconnection point that connect Internet access providers together so that users that are geographically far away can be reached. NAP similar to an airport. Each airline (ISP) can rent some space (edge routers) at the airport (NAP) and can allow passengers (packets) to get destinations the airline(ISP) may not service. An Internet exchange point (IX or IXP) is a physical infrastructure through which Internet service providers (ISPs) exchange Internet traffic between their networks (autonomous systems). IXPs reduce the portion of an ISP's traffic which must be delivered via their upstream transit providers, thereby reducing the average per-bit delivery cost of their service. Furthermore, the increased number of paths learned through the IXP improves routing efficiency and fault-tolerance. Tier 1 ISP Tier 1 ISP Introduction

22 Tier-1 ISP: e.g., Sprint Sprint US backbone network Introduction

23 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-2 ISPs also peer privately with each other, interconnect at NAP 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 1 ISP NAP Short for point of presence, an access point to the Internet. ISPs have typically multiple POPs. A point of presence is a physical location, either part of the facilities of a telecommunications provider that the ISP rents or a separate location from the telecommunications provider, that houses servers, routers, ATM switches and digital/analog call aggregators. Tier 1 ISP Tier 1 ISP Introduction

24 Internet structure: network of networks
“Tier-3” ISPs and local ISPs last hop (“access”) network (closest to end systems) local ISP Tier 3 Local and tier- 3 ISPs are customers of higher tier ISPs connecting them to rest of Internet Tier-2 ISP Tier 1 ISP NAP Tier 1 ISP Tier 1 ISP Introduction

25 Internet structure: network of networks
a packet passes through many networks! local ISP Tier 3 ISP local ISP local ISP local ISP Tier-2 ISP Tier 1 ISP NAP Tier 1 ISP Tier 1 ISP local ISP local ISP local ISP local ISP Introduction

Download ppt "02 - Switches and Access Introduction."

Similar presentations

Introduction 2 1: Introduction.

Introduction 2 1: Introduction.
CS 381 Introduction to computer networks Lecture 2 1/29/2015.

CS 381 Introduction to computer networks Lecture 2 1/29/2015.
James 1:5 If any of you lacks wisdom, he should ask God, who gives generously to all without finding fault, and it will be given to him.

James 1:5 If any of you lacks wisdom, he should ask God, who gives generously to all without finding fault, and it will be given to him.
Aleksandar, Accounts have been created for any students in EECS 340 who did not already have one. Physical access to the labs has also been granted. If.

Aleksandar, Accounts have been created for any students in EECS 340 who did not already have one. Physical access to the labs has also been granted. If.
Introduction© Dr. Ayman Abdel-Hamid, CS4254 Spring 20061 CS4254 Computer Network Architecture and Programming Dr. Ayman A. Abdel-Hamid Computer Science.

Introduction© Dr. Ayman Abdel-Hamid, CS4254 Spring CS4254 Computer Network Architecture and Programming Dr. Ayman A. Abdel-Hamid Computer Science.
5: DataLink Layer5-1 Chapter 5 Link Layer and LANs Computer Networking: A Top Down Approach Featuring the Internet, 3 rd edition. Jim Kurose, Keith Ross.

5: DataLink Layer5-1 Chapter 5 Link Layer and LANs Computer Networking: A Top Down Approach Featuring the Internet, 3 rd edition. Jim Kurose, Keith Ross.
CS 325 Computer Networks Sami Rollins Fall 2003.

CS 325 Computer Networks Sami Rollins Fall 2003.
Network Layer4-1 Chapter 4 Network Layer Computer Networking: A Top Down Approach Featuring the Internet, 3 rd edition. Jim Kurose, Keith Ross Addison-Wesley,

Network Layer4-1 Chapter 4 Network Layer Computer Networking: A Top Down Approach Featuring the Internet, 3 rd edition. Jim Kurose, Keith Ross Addison-Wesley,
Lecture 2 1-1 Internet Overview: roadmap 1.1 What is the Internet? (A simple overview last week) Today, A closer look at the Internet structure! 1.2 Network.

Lecture Internet Overview: roadmap 1.1 What is the Internet? (A simple overview last week) Today, A closer look at the Internet structure! 1.2 Network.
1 Day 01 - The Internet. 2 Chapter 1 Introduction Computer Networking: A Top Down Approach Featuring the Internet, 3 rd edition. Jim Kurose, Keith Ross.

1 Day 01 - The Internet. 2 Chapter 1 Introduction Computer Networking: A Top Down Approach Featuring the Internet, 3 rd edition. Jim Kurose, Keith Ross.
1: Introduction1 Part I: Introduction Chapter goal: r get context, overview, “feel” of networking r more depth, detail later in course r approach: m descriptive.

1: Introduction1 Part I: Introduction Chapter goal: r get context, overview, “feel” of networking r more depth, detail later in course r approach: m descriptive.
6: Wireless and Mobile Networks6-1 19 - Wireless LANs.

6: Wireless and Mobile Networks Wireless LANs.
Introduction1-1 CS 325 Computer Networks Sami Rollins Fall 2005.

Introduction1-1 CS 325 Computer Networks Sami Rollins Fall 2005.
Chapter 1 Introduction Computer Networking: A Top Down Approach 6th edition Jim Kurose, Keith Ross Addison-Wesley March 2012 A note on the use of these.

Chapter 1 Introduction Computer Networking: A Top Down Approach 6th edition Jim Kurose, Keith Ross Addison-Wesley March 2012 A note on the use of these.
Introduction A closer look at network structure: network edge: – hosts: clients and servers – servers often in data centers  access networks, physical.

Introduction A closer look at network structure: network edge: – hosts: clients and servers – servers often in data centers  access networks, physical.
6: Wireless and Mobile Networks6-1 Chapter 6 Wireless and Mobile Networks Computer Networking: A Top Down Approach Featuring the Internet, 3 rd edition.

6: Wireless and Mobile Networks6-1 Chapter 6 Wireless and Mobile Networks Computer Networking: A Top Down Approach Featuring the Internet, 3 rd edition.
Introduction1-1 Chapter 1 Computer Networks and the Internet Computer Networking: A Top Down Approach Featuring the Internet, 2 nd edition. Jim Kurose,

Introduction1-1 Chapter 1 Computer Networks and the Internet Computer Networking: A Top Down Approach Featuring the Internet, 2 nd edition. Jim Kurose,
Introduction1-1 Chapter 1 Introduction Computer Networking: A Top Down Approach, 4 th edition. Jim Kurose, Keith Ross Addison-Wesley, July 2007. A note.

Introduction1-1 Chapter 1 Introduction Computer Networking: A Top Down Approach, 4 th edition. Jim Kurose, Keith Ross Addison-Wesley, July A note.
CS 3830 Day 2 Introduction 1-1. Announcements  Program 1 posted on the course web  Project folder must be in 1DropBox on S drive by: 9/14 at 3pm  Must.

CS 3830 Day 2 Introduction 1-1. Announcements  Program 1 posted on the course web  Project folder must be in 1DropBox on S drive by: 9/14 at 3pm  Must.
Introduction 1-1 Lecture 3 Computer Networking: A Top Down Approach 6 th edition Jim Kurose, Keith Ross Addison-Wesley March 2012 CS3516: These slides.

Introduction 1-1 Lecture 3 Computer Networking: A Top Down Approach 6 th edition Jim Kurose, Keith Ross Addison-Wesley March 2012 CS3516: These slides.

Similar presentations

Ads by Google