Internet and Intranet Fundamentals

Class 3

Session A

Topics

• TCP/IP– Comer Animations and Images

• Internet Architecture (SessionB)

• Regulation (Session B)

TCP/IP• Comer Animations and Images

– http://www.netbook.cs.purdue.edu/subjindx/indx420.htm

• ARP and Reverse ARP– Address Resolution Protocol

• IP layer must pass to datalink layer the datalink adress of the destination interface

– on same network

• ARP automates address table update– uses broadcast

– RARP• knows frame address, must find own IP address

TCP / IP

• ICMP = Internet Control Message Protocol– routers generate most ICMP traffic– most common types

• destination unreachable: can’t find routing table entry

• routing redirect: better route exists

• time expired: ttl = 0; traceroute uses this

• echo request / echo reply: ping uses this

TCP / IPRouting Architecture

• Autonomous Systems (AS)– collection of routers under single administration– use same routing protocol

• Interior Gateway Protocol (IGP)

• keeps routers informed of interior routes

– AS-to-AS connection uses a different protocol• Exterior Gateway Protocol

• policy routing, transit traffic, local traffic (originating within)

TCP / IPRouting Architecture

• Routing Protocols

• Reachability Protocols– whether path exists

• EGPs and BGPs (Border Gateway Protocol)

• Distance Vector Protocol– distance metric to remote network

• RIP = Routing Information Protocol– broadcast exchange of routing information

– uses UDP

• OSPF = Open Shortest Path First

Internet Architecture• Overview

• ISPs– Internet Service Providers

• Regional Networks

• NAPs and MAEs

• U.S. Commercial Backbone

• Internet Monitoring

Internet ArchitectureOverview

• A Network of Networks– internetworking

• The Big Picture– http://navigators.com/internet_architecture.html

ISPs

• Points of Presence (POPs)

• Dial-Up and Dedicated Network Connections– variety of underlying technologies– PPP (Point-to-Point Protocol)

• modems

– ISDN (Integrated Services Digital Network)– Frame Relay, Dedicated T-1– ADSL and Cable Modems

ISPs

• Large and Small

• Connect to Regional Network– may be a regional network

• Larger Players– UUNet, PSINet, and Netcom– Telcos: MCI, ATT

ISPs

• Internet Access also provided by– OSP (Online Service Providers)

• AOL, Compuserve, Prodigy

• For a complete list of ISPs seeThe List: http://thelist.internet.com/

• IPPs (Internet Presence Providers)– same as ISP but no access provided

ISP Technology

• Aggregators– also known concentrators– handles

• incoming dial-up calls (say, 100)

• a few ISDN lines

• leased-line connections (T-1)

• frame relay

• and function as a router to the internal ISP network

ISP Technology

Regional Networks

• BARRNet: Northern Central California (CA)

• CERFnet: Western US and International

• CICnet: Midwest US (MN, WI, IA, IN, IL, MI, OH)

• MIDnet: Mid-US (NE, OK, AR, MO, IA, KS, SD)

• NEARNET: Northeastern US (ME, NH, VT, CT, RI, MA)

• NYSERNet: Northeastern US (NY...)

• SURAnet: Southeastern US (WV, VA, SC, NC, TN, KY, LA, MS, AL, GA, FL, Washington, D.C., MD, DE)

• Westnet: Western US (AZ, CO, ID, NM, UT, WY)

Regional NetworksCERFnet (now AT&T)

Regional NetworksCERFnet (now AT&T)

Regional Networks

NAPs and MAEs

• NAP = Network Access Point– originally NFS

• MAE = Metropolitan Area Exchange– MCI Worldcom has a service mark on this– Tier-1

• MAE-East (D.C.) and MAE-West (San Jose)

– Tier-2• LA, Chicago, Dallas, Houston, New York

– Giant LAN switch (FDDI)

MAE-Los Angelescat5500/129 198.32.146.20 triton.cerf.netcat5500/129 198.32.146.14 mae-la.exodus.netcat5500/129 198.32.146.12 mae-la.px.concentric.netcat5500/129 198.32.146.16 mae-la-CCIBRT.mediaone.netcat5500/129 198.32.146.18 f5.peer1.lax1.genuity.netcatalyst1/6 198.32.146.19 mae-la.ware.netcatalyst1/7 198.32.146.25 mae-la.eni.netcatalyst2/4 198.32.146.23 mae-la.intelenet.netisi-cat5500/130 198.32.146.26 maela-lap.digilink.netisi-cat5500/136 198.32.146.17 mae-la.lap.interworld.netisi-cat5500/137 198.32.146.10 lap.ln.netisi-cat5500/138 198.32.146.21 mae-la.above.netisi-cat5500/139 198.32.146.24 mae-la.zocalo.netisi-cat5500/140 198.32.146.15 e0.br1.USC.globalcenter.netisi-cat5500/194 198.32.146.3 m.ep.netisi-cat5500/202 198.32.146.27 lap.berkeley.eduisi-cat5500/203 198.32.146.11 sandbox.ep.netisi-cat5500/204 198.32.146.111 iosv6-7k.ep.net(unknown) 198.32.146.13 mae-la.ni.net

U.S. Commercial Backbone

• ANS (formerly the NSF backbone, now owned by MCI WorldComm)

• AT&T Network Services

• BBN Planet

• MCI WorldCom

• Sprintlink

• UUNET (now owned by MCI WorldCom)

• PSI

Regional NetworksPSINet & UUNET

• Performance Systems Intenational– based in Herndon, VA– http://www.psi.com/network/NorthAmer.html

• UUNET– MCI’s internet subsidiary– http://www.uunet.com/network/northam.htm

U.S. Commercial Backbone

• Minor ISPs Interconnect to Regional Networks at Tier-2 NAPs and MAEs– T-1, T-3

• Regional Networks Connect to Backboneat NAPs– T-3, OC-3, OC-12 and up

Internet Monitoring

• http://www.mids.org/

“MIDS examines the composition, content, and users of the Internet and other networks in the Matrix of all computers worldwide that exchange electronic mail. We organize information on many such topics textually, graphically, and geographically, and publish it in many places, including our own.”

Internet Monitoring Network Wizards http://www.isc.org/ds/hosts.html