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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Questions about Internet Packet Losses
Hello, and best wishes for what's left of 1997. Now, if you would, ... Below are some questions I hope you'll help me answer about packet loss on the Internet. Here are two paragraphs taken from: http://www.merit.edu/~ipma/netnow/docs/info.html: "Early experiments with NetNow show that 30% packet loss between public exchange points is common for major Internet service providers during peak usage periods. The initial investigation also suggests that loss rates are closely related to bandwidth usage and congestion problems. Although some of the packet loss is inadvertent, a large percentage of the public exchange point connectivity problems reflect intentional engineering decisions by Internet service providers based on commercial settlement issues. "The high packet loss may not generally reflect problems seen by the majority of customers of the larger network service providers. In fact, increasing levels of Internet traffic are not traversing the public exchange points. Instead, many large service providers are migrating their inter-provider traffic to private exchange points, or direct connections to other providers. Merit is working closely with providers to develop tools and infrastructure that more closely reflect Internet performance as observed by the majority of backbone customers." Questions: Are you familiar with this packet loss data from Merit? If not, please see above URL. Is Merit's packet loss data (NetNow) credible? Do packet losses in the Internet now average between 2% and 4% daily? Are 30% packet losses common during peak periods? Is there any evidence that Internet packet losses are trending up or down? If Merit's data is not correct, where has Merit gone wrong? Where is there better data? Were Merit's data correct, what would be the impact of 30% packet losses on opening up TCP connections? On TCP throughput, say through a 28.8Kbps modem? On Web throughput, since so many TCP connections are involved? On DNS look-ups? On email transport? How big a problem is HTTP's opening of so many TCP connections? Does TCP need to operate differently than it does now when confronted routinely with 30% packet losses and quarter-second transit delays? What is the proper response of an IP-based protocol, like TCP, as packet losses climb? Try harder or back off or what? How robust are various widespread TCP/IP implementations in the face of 30% packet loss and quarter-second transit delays? Is the Internet's sometimes bogging down due mainly to packet losses or busy servers or what, or does the Internet not bog down? What fraction of Internet traffic still goes through public exchange points and therefore sees these kinds of packet losses? What fraction of Internet traffic originates and terminates within a single ISP? Where is the data on packet losses experienced by traffic that does not go through public exchange points? If 30% loss impacts are noticeable, what should be done to eliminate the losses or reduce their impacts on Web performance and reliability? Are packet losses due mainly to transient queue buffer overflows of user traffic or to discards by overburdened routing processors or something else? What does Merit mean when they say that some of these losses are intentional because of settlement issues? Are ISPs cooperating intelligently in the carriage of Internet traffic, or are ISPs competing destructively, to the detriment of them and their customers? Any help you can offer on these questions would be appreciated. /Bob Metcalfe, InfoWorld ______________________________________________ ______________________________________________ Dr. Robert M. ("Bob") Metcalfe VP Technology, International Data Group InfoWorld columns: www.infoworld.com Mail: [email protected] Telephone: 617-534-1215 Conference Chairman for ACM97: The Next 50 Years of Computing San Jose Convention Center, March 1-5, 1997 Registration information: www.acm.org/acm97 Register now at 1-800-342-6626 ______________________________________________ ______________________________________________ - - - - - - - - - - - - - - - - -
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