1. doc.: IEEE 802.11-09/1317r0 Submission December 2009 Vinko Erceg, BroadcomSlide 1 Internet Traffic Modeling Date: 2009-12-09 Authors: NameAffiliationsAddressPhoneEmail Sai NandagopalanBroadcomSan Diego858 521 2192nsai@broadcom.com Vinko ErcegBroadcomSan Diego858 521-5885verceg@broadcom.com

2. doc.: IEEE 802.11-09/1317r0 Submission December 2009 Vinko Erceg, BroadcomSlide 2 Why Model Internet Traffic? Why model traffic? –The traffic model is the key for determining the performance of the system. The more accurate is the traffic model the better is the system quantified in terms of its performance. –Traffic model in the evaluation methodology document should focus on capturing the accents of the application which posts special demand on the system performance. What is being modeled here? –We are modeling TCP and Web browsing This document proposes to changes that were presented in IEEE 802.11-09/1216r1. –Why? –Almost all of us use standard simulators such as OPNET, NS2, OMNET etc. –These simulators are rich enough to have most types of TCP inbuilt with all the TCP parameters. –Additionally, we want to include reference to IEEE 802.11n evaluation methodology document

3. doc.: IEEE 802.11-09/1317r0 Submission December 2009 Vinko Erceg, BroadcomSlide 3 Modeling TCP Traffic Almost all the file transfers between individual devices that are connected via IEEE 802.11 and its extensions happens through TCP. –This is the recommended protocol for all traffic that passes through the IP stack We consider a simple file transfer. –The file size is fixed at 10 GByte. In this profile the PCP is also an AP and is connected to the backbone. Since the packet size is limited by Ethernet, we set it as 1500 bytes

4. doc.: IEEE 802.11-09/1317r0 Submission December 2009 Vinko Erceg, BroadcomSlide 4 TCP Procotol Configuration TCP Configuration Parameters in Simulators MSSEthernet (1500 bytes) Receive Buffer (Bytes)65535 Receive Buffer AdjustmentNone Delayed ACK MechanismSegment/Clock based Max. ACK Delay (Sec)0.05 Slow Start Initial Count (MSS)1 Fast RetransmitEnabled Duplicate ACK Threshold3 Fast RecoveryReno Window ScalingEnabled Selective ACK (SACK)Disabled ECN CapabilityDisabled Segment Send ThresholdByte Boundary Active Connection ThresholdUnlimited Karn’s AlgorithmEnabled Nagle AlgorithmDisabled Initial Sequence NumberAuto Complete Initial RTO (sec)3.0 Min RTO (sec)1.0 Max RTO (sec)64 RTT Gain0.125 Deviation Gain0.25 RTT Deviation Coefficient4.0 Timer Granularity0.25 The table on the right outlines the TCP configuration in all simulators. All these parameters are available. These were the same parameters that were used in IEEE 802.11n evaluation methodology document.

5. doc.: IEEE 802.11-09/1317r0 Submission December 2009 Vinko Erceg, BroadcomSlide 5 Modeling HTTP Traffic (1) HTTP traffic characterization is quite complex and is a function of –Structure of WWW pages and –Nature of human interaction Based on the above properties, it is bursty and is modeled by ON/OFF sources –ON periods represent the webpages being transferred from the server to client and the OFF periods refers to the reading time of the user –Also a webpage consists of multiple subpages and each main page reference generates the request of those subpages Reading TimeFirst Packet of SessionLast Packet of SessionReading Time

6. doc.: IEEE 802.11-09/1317r0 Submission December 2009 Vinko Erceg, BroadcomSlide 6 Modeling HTTP Traffic (2) The parameters of HTTP file transfer are: –SM: Size of main object in page –Nd: Number of embedded objects in a page –SE: Size of an embedded object in page –Dpc: Reading time –Tp: Parsing time for the main page The table on the right highlights the components and their distributions

7. doc.: IEEE 802.11-09/1317r0 Submission December 2009 Vinko Erceg, BroadcomSlide 7 Conclusions We have outlined the models of TCP traffic and HTTP traffic to be used for evaluation methodology document for TGad –The TCP traffic is the same as what was done in the evaluation methodology document in IEEE 802.11n –The HTTP traffic is represented by few distributions that have been taken from extensive studies of references [1-6].

8. doc.: IEEE 802.11-09/1317r0 Submission December 2009 Vinko Erceg, BroadcomSlide 8 References [1] P. Barford and M Crovella, "Generating Representative Web Workloads for Network and Server Performance Evaluation" In Proc. ACM SIGMETRICS International Conference on Measurement and Modeling of Computer Systems, pp. 151-160, July 1998. [2] S. Deng. “Empirical Model of WWW Document Arrivals at Access Link.” In Proceedings of the 1996 IEEE International Conference on Communication, June 1996. [3] R. Fielding, J. Gettys, J. C. Mogul, H. Frystik, L. Masinter, P. Leach, and T. Berbers-Lee, "Hypertext Transfer Protocol - HTTP/1.1", RFC 2616, HTTP Working Group, ftp://ftp.Ietf.org/rfc2616.txt, June 1999. [4] B. Krishnamurthy and M. Arlitt, "PRO-COW: Protocol Compliance on the Web", Technical Report 990803-05-TM, AT&T Labs, http://www.research.att.com/~bala/papers/procow-1.ps.gz, August 1999. [5] B. Krishnamurthy and C. E. Wills, "Analyzing Factors That Influence End-to-End Web Performance", Computer Networks: The International Journal of Computer and Telecommunications Networking, Volume 33, Issue 1-6, pp. 17-32, June 2000. [6] H. K. Choi, J. O. Limb, "A Behavioral Model of Web Traffic", Proceedings of the seventh International Conference on Network Protocols, 1999, pp. 327-334, November 1999.