NETWORK WORLD NEWSLETTER: STEVE TAYLOR AND JOANIE WEXLER ON WIDE AREA NETWORKING 08/19/04 Today's focus: Boosting TCP WAN performance
Dear [EMAIL PROTECTED], In this issue: * Internap speeds up TCP ACKs over WAN * Links related to Wide Area Networking * Featured reader resource _______________________________________________________________ This newsletter is sponsored by SBC Gimme Shelter! Converged Services Spell Relief For Beleaguered Network Managers Switched IP networks are rapidly becoming the corporate communications architecture of choice. By converging voice, data and video onto IP telephony platforms and Virtual Private Networks, enterprises can supply bandwidth when and where end users need it, while significantly lowering administrative and equipment costs. Click here to download this Whitepaper now http://www.fattail.com/redir/redirect.asp?CID=72624 _______________________________________________________________ CHECK OUT NW FUSION'S NEW WHITE PAPER LIBRARY Just launched: NW Fusion's White Paper Library with new features and improved capabilities! Sort NW Fusion's library of white papers by Date and Vendor, view white papers by TECHNICAL CATEGORY, mouse over white paper descriptions and take advantage of our IMPROVED white paper search engine. CLICK HERE: http://www.fattail.com/redir/redirect.asp?CID=72551 _______________________________________________________________ Today's focus: Boosting TCP WAN performance By Steve Taylor and Joanie Wexler As we have observed frequently in this newsletter, there has been much innovation in the past few years to help you improve the performance of your networked applications over the WAN. Among the methods we've explored are compression, caching and traffic shaping. These functions can be activated using stand-alone appliances or capabilities embedded in routers. One issue we haven't discussed is the nature of TCP - the commonly used Layer-4 transport protocol - and how it tends to behave over the wide area. TCP is connection-oriented and reliable, because it has flow-control mechanisms in it. However, the propagation delay caused by distance in wide-area networking can mean problems for TCP's built-in flow-control mechanisms. Some vendors - most recently Internap Network Services - have attempted to mitigate the throughput ramifications associated with these issues by adjusting TCP's feedback mechanism. Specifically, Internap, for one, now makes an appliance that speeds up the frequency at which TCP sends acknowledgements, or ACKs, to transmitting devices that packets have been received. When it takes a long time for ACKs to be received, TCP assumes congestion on the link and adjusts the sending rate of the transmitting endpoint accordingly to ease congestion. However, when the ACK receive time is prolonged by propagation delay caused by distance, the transmission rate can be reduced unnecessarily, degrading throughput. The Internap Flow Control Xcelerator (FCX), announced early this month, is an appliance that sits inline on the LAN side of the router at the WAN edge, Internap CTO Ali Marashi explains. In today's implementation, you need a device at both ends of a link for application traffic to be TCP-accelerated, he says. The pair of appliances can reportedly accelerate TCP-based application performance by as much as 40 times. Marashi, for example, says it's not uncommon to see cross-country FTP traffic from California to Virginia on a 200M bit/sec link degrade to just 4M bit/sec throughput. The FCX can boost it back up to 160M bit/sec, he says. Other companies have also attempted to twiddle with TCP to accelerate throughput over the WAN; most notably, those that make satellite modem and routing equipment (Encore Networks, V-One), where propagation delay from ground-to-satellite-to-ground wreaks particular havoc with TCP windowing. Internap appliances are sold by per-site bandwidth speed; a one-time license key per site for a 1.5M-bit/sec connection lists at $10,000 (per end) plus a $1,500 annual service fee (per end). Internap also sells route-control products and services via its 2003 acquisitions of appliance-maker netVmg and route-control product-maker and service provider Sockeye Networks. RELATED EDITORIAL LINKS Satellite VPNs to address performance, security issues Network World Wireless in the Enterprise Newsletter, 03/17/03 http://www.nwfusion.com/nlwan519 Internap integrates route optimization acquisitions Network World, 05/17/04 http://www.nwfusion.com/news/2004/0517internap.html Internap acquires Sockeye, netVmg Network World, 10/13/03 http://www.nwfusion.com/news/2003/1013internap.html _______________________________________________________________ To contact: Steve Taylor and Joanie Wexler Steve Taylor is President of Distributed Networking Associates and Publisher/Editor-in-Chief of Webtorials.Com. For more detailed information on most of the topics discussed in this newsletter, connect to Webtorials.Com <http://www.webtorials.com/>, the first Web site dedicated exclusively to market studies and technology tutorials in the Broadband Packet areas of Frame Relay, ATM, and IP. He can be reached at <mailto:[EMAIL PROTECTED]> Joanie Wexler is an independent networking technology writer/editor in California's Silicon Valley who has spent most of her career analyzing trends and news in the computer networking industry. She welcomes your comments on the articles published in this newsletter, as well as your ideas for future article topics. Reach her at <mailto:[EMAIL PROTECTED]>. _______________________________________________________________ This newsletter is sponsored by SBC Gimme Shelter! Converged Services Spell Relief For Beleaguered Network Managers Switched IP networks are rapidly becoming the corporate communications architecture of choice. By converging voice, data and video onto IP telephony platforms and Virtual Private Networks, enterprises can supply bandwidth when and where end users need it, while significantly lowering administrative and equipment costs. Click here to download this Whitepaper now http://www.fattail.com/redir/redirect.asp?CID=72624 _______________________________________________________________ ARCHIVE LINKS Archive of the WAN newsletter: http://www.nwfusion.com/newsletters/frame/index.html _______________________________________________________________ FEATURED READER RESOURCE WONDERING IF YOUR PAY IS UP TO SNUFF? Check out Network World's 2004 Salary Calculator to see if you're getting paid what you're worth. Using data collected in the 2004 Network World Salary Survey, we've programmed this calculator with several categories that could affect your pay. Answer the questions and find out what the average salary is for your job category. Click here: <http://www.nwfusion.com/salary/2004/calculator.html> _______________________________________________________________ May We Send You a Free Print Subscription? You've got the technology snapshot of your choice delivered at your fingertips each day. 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