DOCUMENT RESUME ED 290 427 IR 012 942 AUTHOR Finn, Gregory G. TITLE Routing aid Addressing Problems in Large Metropolitan-Scale Internetworks. ISI Research Repo: t. INSTITUTION University of Southern California, Marina del Rey. Information Sciences Inst. SPONS AGENCY Advanced Research Projects Agency (DOD), Washington, D.C. REPORT NO ISI/RR-87-180 PUB DATE Mar 87 CONTRACT MDA90381-C-0335 NOTE 66p. PUB TYPE Reports Research/Technical (143) EDRS PRICE MF01/PC03 Plus Postage. DESCRIPTORS *Algorithms; *Computer Networks; -Computer System Design; Models; *Protocol Analysis IDENTIFIERS *Network Architecture; Packet Switched Networks ABSTRACT This report discusses some of the problems and limitations in existing internetwork design for the connection of packet-switching networks of different technologies and presents an algorithm that has been shown to be suitable for internetworks of unbounded size. Using a new form of address and a flat routing mechanism called Cartesian routing, this algorithm is designed to solve three problems: (1) overhead that increases with size and thus limits expansion; (2) an inability to allow mobile hosts free movement throughout the internetwork; and (3) routing and packet processing requiring large tables or substantial coputation per packet. It also retains two desirable attributes of current algorithms: robustness in the presence of link and router failures, and the use of short paths. This report discusses (1) routing and addressing problems in large metropolitan scale internetworks; (2) Cartesian routing; (3) heuristic modifications; (4) congestion control; (5) applying Cartesian routing to a metropolitan region; (6) host mobility; and (7) simulating Cartesian routing. A model for minimizing hop counts in point--to -point networks is appended and 25 references are provided. (RP) **************R******************************4************************* Reproductions supplied by EDRS are the best that can be made from the original document. **************************************************. **************^**** U $ DEPARTMENT OFEDUCATION Office of Educattoiial Research and Improvement ISI Research Report EDUCATIONAL RESOURCESINFORMATION CENTER (ERIC) f,This document has been reproducedas ISI/RR -87-180 received from the personor organization originating It r, Minor changes have beenmade to improve March 1987 reproduction Quality Points of new or opinions statedin this docu meat do not necessarily representofficial rO OERI position or policy Ui L n,lrrs ri j it 1 s Uhl 'regory G. Finn Routing and Addressing Problems in Large Metropolitan-scale Internetworks INFORMATION WM./ 1171. SCIENCES INSTITUTE 213A22- 1511 4676 Admiral!) la& ,;ry/Califurnia c02Q2-66Q5 2 BEST COPYAVAILABLE Unclassified 3ECORITY CLASSIFICATION OF THIS PAGE REPORT DOCUMENTATION PAGE 13 REPORT SECURITY CLASSIFICATION 1 lb. RESTRICTIVE MARK.' IS Unclassified 2a SECURITY CLASSIFICATION AUTHORITY 3. DISTRIBUTION/AVAILABILITY OF REPORT 2b DECLASSIFICATION / DOWNGRADING SCHEDULE This document is approved for public release; distribution is unlimited 4 PERFORMING ORGANIZATION REPORT NUMBER(S) 5. MONITORING ORGANIZATION REPORT NUMBERS) ISI/RR-87-180 6a NAME OF PERFORMING ORGANIZATION 6b OFFICE SYMBOL 7a. NAME OF MONITORING OR(1^NIZATION (If applicable) USC/Information Sciences Institute 6c. ADDRESS (City, State, and ZIP Code) 7b. ADDRESS (City, State, and ZIP Code) 4676 Admiralty Way Marina del Rey, CA 90292 8a, NAME OF FUNDING/SPONSORING 8b. OFFICE SYMBOL 9. PROCUREMENT INSTRUMENT IDENTIFICATION NUMBER ORGANIZATION (If applicable) MDA903 81 C 0335 Advanced Research Projects Agency 8c ADDRESS (City, State, and ZIP Code) 10 SOURCE OF FUNDING NUMBERS 1400 Wilson Boulevard PROGRAM PROJECT TASK WORK UNIT Arlington, VA 22209 ELEMENT NO. NO. NO. ACCESSION NO 11 TITLE (Include Security Classifi.ation) Routing and Addressing Problems in Large Metropolitan-scale Internetworks (Unclassified) 12 PERSONAL AUTHOR(S) Finn, Gregory G. 13a. TYPE OF REPORT I13b. TIME COVERED 114 DATE OF REPORT (Year, Month, Day)115 PAGE COUNT Research Reportrt FROM TO 1987, March 66 16 SUPPLEMENTARY NOTATION 17 ':OSATI CODES 18. SUBJECT TERMS (Continue on reverse if necessary and identify by block number) FIELD GROUP SUB-GROUP computer networks, network architecture, networks, network design, 09 02 protocols 19 ABSTRACT (Continue on revers if necessary and identify by block number) Digital packet networking technology is spreading rapidly into the commercial sector.Currently, most networks are isolated local area networks. This isolation is counterproductive. Within the next twenty years it should be possible to connect these networks to one another via a vast internetwork. A metropolitan internetwork must be capable of connecting many thousand networks anda national one several million. It is difficult to extend current internetworking technology to this scale. Problems include routing and host mobility. This report addresses these problems by developingan algorithm that retains robustness and has desirable commercial characteristics. 20. DISTAIBUTION/AVAILABILITY OF ABSTRACT 21. ABSTRACT SECURITY CLASSIFICATION IZIUNCLASSIFIED/UNUMIl ED 0 SAME AS RPT. 0 °TIC USERS Unclassified NAME OF RESPONSIBU INDIVIDUAL el a oyazo 22b. TELEPHONE (Include Area Code)22c. OFFICE SYMBOL Victor Brown 213-822-1511 83 APR edition may be used until exhausted. OD FORM 1473,84 MAR SECURITY CLASSIFICATION OF THIS PAGE All other editions are obsolete. Unclassified 3 ISI Research Report ISI/RR -87-180 March 1987 Unitersity of Southern California Gregory G. Finn :::::::::::::::::.: A::::,:x:.1:M Routing and Addressing Problems in Large Metropolitan-scale fnternetworks INFORMATION SCIENCESf 121 INSTITUTE 213/822-1511 46 76 Admiralty Way/Afarina del Rey/California 90292-6605 This research is supported by the Defense Advanced ResearchProtects Agency under Contract No MDA903 81 C 0335 Views and conclusions contained in this report are the author's and shouldnot be interpreted as representing t le official opinionor policy of DARPA, the U S Government, or anyperson or agency connected with them. 4 Acknowledgments The author would like to thank Al Beebe, Ron Castles, and Jon Postel for their help and suggestions. Also I thank Sheila Coyazo for the pains she incurred editing this. Routing and AddressingProblems in Large Metropolitan Scale Internetworks Introduction Internetworking is an area of research thatconcerns the connection of packet- switching networks of different technologies.Much of the early work in thisarea began about ten yearsago on the ARPANET [Cerf][Cerf-2].The ARPANET conversion into the ARPA-Internetwas completed in January 1983. An internet is constructed by connecting separatenetworks to one another viagateways [Sunshine]. Gatewaysare responsible for transparent encapsulation of networks and routing of packets thatcross network boundaries. The widespread geography of theARPA-Internet was inherited from the original ARPANET. Its nearly 125gateways interconnect up to 350 networks, the majority of which are localarea networks. By comparison, a prototypical metropolitan area is asquare 400 by 400 blocks.If one assumes that each neighborhood of foursquare blocks and each major office buildingmay eventually have its own local area network, thena metropolitan-scale internetwork must allow the interconnection of 40,000component networks and a national internetwork must interconnect several million. A networkof this scale will carryvery heavy traffic loads, which will placestrong demands on any router to be fast and efficient. Against this background,we discuss some problems and limitations in existing internetwork design, and attempt to solvethem by using a new form of address anda flat routing mechanism called Cartesianrouting. The Problem ofa Network-Centered Address Most internetworksassume that their routing task is finished when a packet is delivered to any gateway of the destinationnetwork. The internet does not route to a destination host, it routes to a destination network. Theuliderlying assumption, that a network contains he best pathto any of its hosts, has negativeconsequences. Location Information and Poor Paths An address is meant to describea location.Internetwork addresses today identify a network, nota location. ARPA and Xerox Internet addresses contain implicit information abouta location but no explicit information. From the address alone, one cannot determine the distanceto a destination or in which direction the destination lies. When presented witha destination address in the ARPANET network, the Internet routes towaru thenearest operating gateway -nto the ARPANET, not to the gatewaynearest the destination host.If a network has significant geographic spread, the routingalgorithm can produce poor paths to the destination. 6 MILNET ARPANET Fig. 1 Routing between networks Figure 1 depicts what happens. Both the ARPANET and the MILNET are distributed across a continent. Assume that host A in the MILNET wishes to communicate with host B in the ARPANET. The ARPA-Internet routing algorithm considers path length to be the number of gateways betvv een the source and destination networks. The true length of the path must measure the distance crossed within each network. Since this is not dore, the routing algorithm considers both the dotted and dashed paths between A and B to have the same length. This results in the needless routing of paucets between two geographically close hosts, back and forth across the continent. Unnecessary Partitioning If one assumes that a network