 Network OptimizationThis newsletter is sponsored by Secure ComputingNetwork World's Network Optimization Newsletter, 11/13/07Cutting WAN lossesBy Ann BednarzDropped packets giving you grief? Out-of-order packets messing with application performance? Silver Peak Systems says it can help tame these problems with the latest enhancements to its WAN acceleration gear. New features from Silver Peak are designed to overcome dropped and misordered packets to improve throughput, particularly on high capacity WANs that can be prone to such problems, says Jeff Aaron, director of product marketing at Silver Peak. In MPLS and IP VPN environments, where routers and links are often oversubscribed, packet delivery issues can increase as throughput increases, for example. It’s common to see averages of 0.5% packet loss with peaks reaching 1%, 2% or even 5%, Aaron says. These problems can lead to excessive retransmissions, which in turn slows data transfers across the WAN.
“As a general rule, packet loss is a bigger issue on bigger pipes,” Aaron says. “If you’ve got a T-1, and you hit packet loss, you can probably use TCP and retransmit and your application may be a bit slower, but traffic will still show up. But if you're doing replication at 100Mbps and you start to drop packets, and your throughput goes down to about 5Mbps, that’s pretty catastrophic. Those applications are going to get broken.” Jim Metzler of analyst firm Ashton, Metzler & Associates, likewise said packet loss and reordering can debilitate key applications across the WAN, “especially in data replication and remote backup scenarios where there are large amounts of sustained traffic.” “As more enterprises move to MPLS and IP VPNs, loss mitigation and reordering techniques will become an increasingly important requirement for WAN optimization devices,” he said in a statement. To expose -- and overcome -- packet loss and ordering issues, Silver Peak gear depends on a few techniques: * Dynamic forward error correction (FEC): FEC technology is used to reconstitute lost packets at the far end of a WAN link in real-time, eliminating the need to retransmit lost data. Silver Peak has offered FEC since 2005. In its latest software release, Silver Peak expanded its ability to work on high capacity links; the current FEC technology can support up to 2Gbps of LAN traffic and 500Mbps of WAN traffic. * Packet order correction: Silver Peak’s NX appliances resequence packets on the far end of a WAN link, prior to delivery, to avoid re-transmissions that occur when packets arrive out of order. “On the far end, if packets are delivered out of order, rather than having to retransmit using TCP, we can reorder them and deliver it to the host,” Aaron says. “This is ideal for real-time traffic, because you’re avoiding the need to have to retransmit, which basically would break replication, voice and video applications.” * Packet striping: A new feature in Silver Peak’s NX appliances, packet striping enables packets to be spread across multiple IP flows to overcome single flow limits in network gear such as routers and firewalls. The result is that a single flow and looks like many flows, which enables higher throughput for high bandwidth applications. * Network and traffic statistics: Silver Peak’s Global Management System provides statistics on bandwidth, latency, loss and out-of-order packets across the WAN. Reporting tools assist with WAN analysis and in the enforcement of service-level agreements. These packet-handling upgrades are included in Version 2.1 of Silver Peak’s appliances and management system. Editor's note: Starting Monday, Nov, 19, this newsletter will be renamed "Network Optimization Alert." Subscribers to the HTML version of this newsletter will notice some enhancements that will provide you with access to more resources relevant to network optimization. You will still receive Ann Bednarz's analysis of this market, which you will be able to read in its entirety online at NetworkWorld.com, along with links to relevant news headlines of the day. We hope you enjoy the enhancements and we thank you for reading Network World newsletters.
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| Contact the author: Ann Bednarz is an associate news editor at Network World responsible for editing daily news content. She previously covered enterprise applications, e-commerce and telework trends for Network World. E-mail Ann. This newsletter is sponsored by Secure ComputingARCHIVEArchive of the Network Optimization Newsletter. BONUS FEATURE90% of IT Managers are leaving their company at risk for a DNS ATTACK. Get the tools and resources you need to keep your DNS healthy and secure. Run a DNSreport on your domain today - 56 critical tests run in 8 seconds. Visit www.dnsreport.com to learn more. (apply coupon NWW2007NLA for a 25% membership discount) PRINT SUBSCRIPTIONS AVAILABLE International subscribers, click here. SUBSCRIPTION SERVICESTo subscribe or unsubscribe to any Network World newsletter, change your e-mail address or contact us, click here. This message was sent to: networking.world@gmail.com. Please use this address when modifying your subscription. Advertising information: Write to Associate Publisher Online Susan Cardoza Network World, Inc., 118 Turnpike Road, Southborough, MA 01772 Copyright Network World, Inc., 2007 |
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