Transcript Session 3A
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 / IP Routing 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 / IP Routing 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 Architecture Overview • 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 see The 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 Networks CERFnet (now AT&T) Regional Networks CERFnet (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 Angeles cat5500/129 cat5500/129 cat5500/129 cat5500/129 cat5500/129 catalyst1/6 catalyst1/7 catalyst2/4 isi-cat5500/130 isi-cat5500/136 isi-cat5500/137 isi-cat5500/138 isi-cat5500/139 isi-cat5500/140 isi-cat5500/194 isi-cat5500/202 isi-cat5500/203 isi-cat5500/204 (unknown) 198.32.146.20 198.32.146.14 198.32.146.12 198.32.146.16 198.32.146.18 198.32.146.19 198.32.146.25 198.32.146.23 198.32.146.26 198.32.146.17 198.32.146.10 198.32.146.21 198.32.146.24 198.32.146.15 198.32.146.3 198.32.146.27 198.32.146.11 198.32.146.111 198.32.146.13 triton.cerf.net mae-la.exodus.net mae-la.px.concentric.net mae-la-CCIBRT.mediaone.net f5.peer1.lax1.genuity.net mae-la.ware.net mae-la.eni.net mae-la.intelenet.net maela-lap.digilink.net mae-la.lap.interworld.net lap.ln.net mae-la.above.net mae-la.zocalo.net e0.br1.USC.globalcenter.net m.ep.net lap.berkeley.edu sandbox.ep.net iosv6-7k.ep.net 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 Networks PSINet & 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 Backbone at 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