(July 1997)
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Firewalls (July 1997) |
Hi: I have a couple of elementary questions. 1) Do heavy traffic web sites like Yahoo, Microsoft, NetScape, Nasdaq (which are averaging over 10 million hits a day) have any type of firewall protection. Client -> Internet -> (Firewall) -> Web-Server Bank If yes, what kind of firewalls are these: screening routers, etc. If not, would the introduction of a firewall affect performance dramatically in a heavy traffic situation. Why is this the case? Are there any studies that looked at the performance affects. 2) In a typical HTTP/1.0 connection, the roundtrip interaction for retrieving a HTML page with one inlined image looks as follows [1] : -- The client opens the TCP connection, resulting in an exchange of SYN packets as part of TCP's three-way handshake procedure. -- The client transmits an HTTP request to the server; the server may have to read from its disk to fulfill the request, and then transmits the response to the client. -- After parsing the returned HTML document to extract the URLs for inlined images, the client opens a new TCP connection to the server, resulting in another exchange of SYN packets. -- The client again transmits an HTTP request, this time for the first inlined image. The server obtains the image file, and starts transmitting it to the client. How will the introduction of a Firewall or Proxy change this interaction. The reason for this question is in understanding and modeling the performance difference between HTTP/1.0 and HTTP/1.1 (persistent and pipelined connections). Has anyone done any performance research on the differences between the two protocols? References: [1] Venkata N. Padmanabhan, Jeffrey C. Mogul, "Improving HTTP Latency", University of California -- Berkeley, Digital Equipment Corporation Western Research Laboratory, October 1994 Thanks in advance, -- Ravi +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Ravi Kalakota POTS: (716) 275-3102 Fax: (716)273-1140 Xerox Assistant Professor of Information Systems Simon School--University of Rochester Rochester, New York 14627 e-mail: kalakota @ uhura . cc . rochester . edu Author of: Frontiers of Electronic Commerce (Addison-Wesley) Electronic Commerce: A Manager's Guide (Addison-Wesley) Readings in Electronic Commerce (Addison-Wesley) http://commerce.ssb.rochester.edu/ ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
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