Internet review

Copyright 2005 John Wiley & Sons, Inc Internet Most used network in the world Not one network, but a network of networks Made up of thousands of networks of –National and state government agencies, –Non-profit organizations and for-profit companies. A rigidly controlled club –To exchange data, these networks must agree to use Internet protocols –TCP/IP MUST be supported by all networks Unrestricted applications and contents –Developed freely

Copyright 2005 John Wiley & Sons, Inc Internet’s Hierarchical Structure National Internet Service Providers (ISPs) –Provide services to their customers and sell access to regional ISPs and local ISPs Regional ISPs –Connect with National ISPs –Provide services to their customers and sell access to local ISPs Local ISPs –Connected to National or Regional ISPs –Sell access to individuals

Copyright 2005 John Wiley & Sons, Inc Internet’s Access Points Network Access Points (NAPs) –Connect National ISPs together –Sometimes large regional and local ISPs also have access directly to NAPs Indiana University, for example, which provides services to about 40,000 individuals, connects directly to the Chicago NAP –About a dozen NAPs in the U.S. –Run by common carriers such as Sprint and AT&T Metropolitan Area Exchanges (MAEs) –Connect Regional ISPs together –About 50 such MAEs in the U.S. today

Copyright 2005 John Wiley & Sons, Inc Basic Internet Architecture

Copyright 2005 John Wiley & Sons, Inc Packet Exchange Charges Peering –ISPs at the same level usually do not charge each other for exchanging messages Higher level ISPs charge lower level ones –National ISPs charge regional ISPs which in turn charge local ISPs Local ISPs charge individuals and corporate users for access

Copyright 2005 John Wiley & Sons, Inc Connecting to an ISP Done by through ISP’s Point of Presence (POP) –A place ISP provides service to its customers Individual users –Typically through a dial-up line using the PPP protocol Handled by the ISP’s modem pool –Userid and password checked by Remote Access Server (RAS) Once logged in, the user can send packets over the phone line Corporate users –Typically access the POP using a T-1, T-3 or ATM OC-3 connections provided by a common carrier Cost = ISP charges + circuit charges

Copyright 2005 John Wiley & Sons, Inc ISP Point-of Presence Modem Pool Individual Dial-up Customers Corporate T1 Customer T1 CSU/DSU Corporate T3 Customer T3 CSU/DSU Corporate OC-3 Customer ATM Switch Layer-2 Switch ISP POP NAP/MAE Remote Access Server ATM Switch Inside an ISP POP

Copyright 2005 John Wiley & Sons, Inc ATM Switch Route Server Router ISP A Router ISP B Router ISP C Router ISP D ISP E ATM Switch ISP F ATM Switch Inside an Internet NAP (Chicago) One of the busiest (4 Gbps; 140 ISPs) Used to exchange routing information through BGP

Copyright 2005 John Wiley & Sons, Inc Internet Backbones in 2002 Backbone circuits for national ISPs –OC-48 and OC-192 (10 Gbps) becoming common –To be converted to OC-192 (10 Gbps) by 2005 –OC-768 (40 Gbps) and use OC-3072 (160 Gbps) in experiment stage Aggregate Internet traffic –Growing rapidly –Expected to reach 40 Terabits per second (Tbps) by –NAPs and MAEs becoming bottlenecks Requiring larger and larger switches

Copyright 2005 John Wiley & Sons, Inc Internet Access Technologies Most commonly used –56K dial-up lines (individuals) –T1 or T3 lines into ISPs (organizations) New access technologies –Commonly called “broadband access” Provide higher speed access –Digital Subscriber Line (DSL) –Cable Modems –Fixed Wireless (including satellite access) –Mobile Wireless (WAP)

Copyright 2005 John Wiley & Sons, Inc Digital Subscriber Line (DSL) A family of point-to-point technologies Designed to provide high speed data transmission over traditional telephone lines –Traditional telephone lines (local loop) Limited capacity due to telephone and switching equipment at the end offices Constrained by 4 KHz voice channel Much higher bandwidth possible (with new technology based equipment  DSL) Requires changing telephone equipment; not rewiring the local loop Not available in all locations in the US –More wide spread in Asia, Europe and Canada

Copyright 2005 John Wiley & Sons, Inc Local Carrier End Office Line Splitter Customer Premises Telephone DSL Modem Hub Computer Local Loop Main Distribution Frame Customer Premises Customer Premises Voice Telephone Network DSL Access Multiplexer ATM Switch ISP POP DSL Architecture

Copyright 2005 John Wiley & Sons, Inc Types of DSL Asymmetric DSL (ADSL) –Uses three FDM channels 4 KHz analog voice channel A simplex data channel for downstream traffic A slower full-duplex data channel for Upstream traffic –Size of digital channels Depends on the distance (CPE-Office) (up to 18,000 ft) Most common (T1): 1.5 Mbps down; 384 Kbps up Very high data rate DSL (VDSL) –Designed for local loops of 4500 ft or less (1000 ft ideal) –Also uses three FDM channels as in ADSL –Size of digital channels (distance sensitive) Most common (1/4OC1): 12 Mbps down; 1.6 Mbps up

Copyright 2005 John Wiley & Sons, Inc TypeMaximum Length of Local Loop Maximum Downstream Rate Maximum Upstream Rate T1 18,000 feet1.5 Mbps384 Kbps E1* 16,000 feet2.0 Mbps384 Kbps T2 12,000 feet6.1 Mbps384 Kbps E2 * 9,000 feet8.4 Mbps640 Kbps * E1 and E2 are the European standard services similar to T1 and T2 services in North America ADSL Data Rates

Copyright 2005 John Wiley & Sons, Inc Cable Modems A digital service offered by cable television companies Data Over Cable Service Interface Specifications (DOCSIS) –Most common protocol used for cable modems –Not a formal standard Offers vary (depends on the quality of cable plant) –In theory: downstream: 27-55Mbps; upstream: 2-10 Mpbs –Typical: downstream: Mbps; upstream 0.2 – 2 Mbps –A few cable companies offer downstream services only Upstream communications using regular telephone lines

Copyright 2005 John Wiley & Sons, Inc Cable Modem Architecture Similar to DSL (with one main difference): –DSL: point-to-point technology –Cable modems: use shared multipoint circuits All messages on the circuit heard by all computers on the circuit  security issue 300 – 1000 customers per cable segment Type of equipment used –Cable Modem Termination System (CMTS) Used for upstream traffic only Converts data from DOCSIS to Internet protocols –Fiber Node with an Optical Electrical (OE) converter –Combiner (for downstream traffic only) Combines Internet traffic with TV video traffic

Copyright 2005 John Wiley & Sons, Inc Cable Company Distribution Hub Cable Splitter Customer Premises TV Cable Modem Hub Computer Shared Coax Cable System Combiner Customer Premises Customer Premises TV Video Network Cable Modem Termination System ISP POP Cable Company Fiber Node Optical/ Electrical Converter Downstream Upstream Router Cable Company Fiber Node Basic Cable Modem Architecture

Copyright 2005 John Wiley & Sons, Inc Fixed Wireless Requires “line of sight” access between transmitters –Requires tall buildings and towers –Common use: provide Internet access to multi-tenant buildings (apartment buildings, hotels, etc.,) Types of FWA –Point-to-point types Used to connect only two locations –Point-multipoint types Allow access by a limited number of stations Designed as an alternative to DSL, cable modems Data access speeds –Range from 1.5 to 11 Mbps

Copyright 2005 John Wiley & Sons, Inc Mobile Wireless Allows users to access the Internet from any location Next major challenge in networking: Widespread mobile high speed Internet access Current Mobile wireless technologies –Slow access speeds compared to DSL,cable modem –WLAN: Higher speed, but limited range and locations –Wireless Application Protocol (WAP) Based on Wireless Application Environment (WAE) and Wireless Markup Language (WML) Streamlines HTTP and HTML for use in the very limited low speed and small screens of mobile devices

Copyright 2005 John Wiley & Sons, Inc Future Access Technologies Passive Optical Networking (PON) –Also called Fiber to the Home –Potential of optical fiber communications to end users Possibility of thousands of channels (with WDM) –Doesn’t require electricity, thus “passive” –Limits its maximum distance (about 10 miles) –No standards yet Ethernet to the Home –Yipes.com is now doing this in several large US cities –Gives home users 10BaseT or 100BaseT connections –A TCP/IP router installed into the customer’s network connect to an Ethernet MAN –No protocol conversion required

Copyright 2005 John Wiley & Sons, Inc Internet Governance No one operates the Internet Closest thing: Internet Society (ISOC) –Open membership professional society –Over 175 organizational and 8000 individual members in over 100 countries –Mission: “Open development, evolution and use of the Internet for the benefit of the people in the world.” –ISOC work areas Public policy: –Involves in debates in copyright, censorship, privacy Education –Training and education programs Standards

Copyright 2005 John Wiley & Sons, Inc ISOC Standard Bodies Internet Engineering Task Force (IETF) –Concerned with evolution of Internet architecture and smooth operation of Internet –Work through groups (organized by topics) –Request For Comments (RFC): basis of Internet standards Internet Engineering Steering Group (IESG) –Responsible for management of the standard process –Establishes and administers rules in creating standards Internet Architecture Board (IAB) –Provides strategic architectural oversight, guidance Internet Research Task Force (IRTF) –Focus on long-term specific issues

Copyright 2005 John Wiley & Sons, Inc Internet 2 Many new projects designing new technologies to evolve Internet Primary North American projects –Next Generation Internet (NGI) funded by NSF Developed very high performance Backbone Network Service (vBNS) –Run by WorldCom –University Corporation for Advanced Internet Development (UCAID) with 34 universities Developed Abilene network (also called Internet 2) –Advanced Research and Development Network Operations Center (ARDNOC) funded by Canadian government Developed CA*Net

Copyright 2005 John Wiley & Sons, Inc Features of Future Internet Access via Gigapops, similar to NAPs –Operate at very high speeds (622 Mbps to 2.4 Gbps) using SONET, ATM and IPv6 protocols IPv6 not IPv4 New protocol development focuses on issues like –Quality of Service –Multicasting New applications include –Tele-immersion –Videoconferencing

Copyright 2005 John Wiley & Sons, Inc Implications for Management Concern about traffic slowing down Internet –New fiber based circuits deployment  overbuilt Many new broadband technologies for high speed Internet access –Simple to move large amount of data into most homes and business  richer multimedia apps Which access technology to dominate? –Challenge: Figure out which one