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 – 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 –

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: 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

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/ triton.cerf.net cat5500/ mae-la.exodus.net cat5500/ mae-la.px.concentric.net cat5500/ mae-la-CCIBRT.mediaone.net cat5500/ f5.peer1.lax1.genuity.net catalyst1/ mae-la.ware.net catalyst1/ mae-la.eni.net catalyst2/ mae-la.intelenet.net isi-cat5500/ maela-lap.digilink.net isi-cat5500/ mae-la.lap.interworld.net isi-cat5500/ lap.ln.net isi-cat5500/ mae-la.above.net isi-cat5500/ mae-la.zocalo.net isi-cat5500/ e0.br1.USC.globalcenter.net isi-cat5500/ m.ep.net isi-cat5500/ lap.berkeley.edu isi-cat5500/ sandbox.ep.net isi-cat5500/ iosv6-7k.ep.net (unknown) 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 – UUNET –MCI’s internet subsidiary –

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

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