Thursday, December 14, 2006
by Jeff Hicks
There's a number of reasons why a company would move to VoIP. Generally there's been some component of cost-savings - it may be in regular long distance savings, it may be in hardware cost savings (versus a PBX system), it may be that you only have one network infrastructure to deploy and manage.
But it's interesting how in the past couple of years, costs have become less of a factor in the decision process. Long-distance rates have dropped, so the cost factor is not quite as pronounced as it used to be, especially considering short-term rollout costs.
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Continue reading "VoIP Traffic Isn't Just Normal Traffic" »
Tuesday, December 12, 2006
By Steven Maercklein and Zack Belcher
While we haven’t had a chance to play with Vista yet, (both of us are on the road all the time and we don’t have access to a lab,) we have been doing a lot of research on the new TCP/IP features of Vista and Longhorn.
We spent some time poring over a document from Microsoft’s Research Asia (the guys who designed the Compound TCP/IP [CTCP] algorithm) and it details how the algorithm works. It doesn’t detail how Microsoft has implemented the algorithm – there are alpha, beta, and gamma values that are tweakable, but it doesn’t go into how Microsoft has tweaked them. It looks like this was a document just to prove that CTCP was feasible and ready to be included in Vista.
It does teach you about the behavior of it and what to expect when seen in action, and it makes reference to the current technologies for congestion avoidance that CTCP is based on. However, there are several features of Vista of concern to those involved in network performance.
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Continue reading "Vista's TCP/IP Promises and Perils" »
Thursday, December 07, 2006
by Ted Romer
I would say, compared to Windows XP’s TCP/IP stack, the Vista stack has been redesigned from the ground up, instead of merely patched. The result is that there are a number of features in the new stack, (which Microsoft calls “The Next Generation TCP/IP Stack”), which are a bit exciting. (Windows Server Longhorn also runs the same stack as Vista.)
There’s been some pretty interesting changes with Receive Window Auto-Tuning and Compound TCP, which provide more aggressive scaling for the network window. Windows scaling is now enabled by default, and is also configured automatically.
If we think about a TCP conversation right now, a sender is given a window as to how much they can send without acknowledgement. The service slowly ramps up in a linear fashion, and if something happens (like a packet loss) we go back to a slow start and slowly ramp up again.
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Continue reading "Vista's "Next Generation" TCP/IP Stack and the Enterprise" »
Friday, November 17, 2006
By Steve Harriman
NetQoS VP Steve Harriman is attending the Gartner Enterprise Networking Summit this week in Las Vegas. It's the first time for the event since the industry downturn in 2001 and NetQoS is exhibiting there because we feel that the role of Networking has been elevated in importance to the point at which it warrants an executive focused event. And, Gartner events are always very educational and well-attended. It's the right place to be.
In addition to Dr.
Malone's keynote and NetQoS's Solution Provider Session, I also went to a talk by Thomas Shelman on the second day of the Summit.
Shelman is CIO of Northrop Grumman Corporation, the second largest defense contractor in the world. As you might imagine, he runs a very large IT organization. Seven CIOs from different business units report to him.
He said his greatest challenge and most rewarding experience, although devastating too, was leading the organization to restore computing and networking infrastructure and services after Katrina pounded two key Northrop Grumman facilities in Louisiana and Mississippi.
The two NG data centers in La. and Miss. were fully configured for redundancy with hot fail-over between systems in both locations. To ensure both data centers would not be affected by “traditional” disasters, such as local power failures, flooding, accidents, etc., they were located 150 miles apart. Unfortunately, the destruction of Katrina was more than 150 miles wide and took both data centers out. (Northrop Grumman put out a
press
release describing the devastation they encountered.)
Continue reading "Notes on the Gartner Summit in Las Vegas, Part 3" »
Wednesday, November 15, 2006
By Steve Harriman
NetQoS VP Steve Harriman is attending the Gartner Enterprise Networking Summit this week in Las Vegas. It's the first time for the event since the industry downturn in 2001 and NetQoS is exhibiting there because we feel that the role of Networking has been elevated in importance to the point at which it warrants an executive focused event. And, Gartner events are always very educational and well-attended. It's the right place to be.
It is worth noting that one of the key themes of the first day is that Network professionals should move beyond the plumbing and be part of the solution to the application delivery problem. The idea that network professionals need to look at response time and focus on end-to-end performance is a message NetQoS has been trying to spread. Here are a few details from the first day keynote to put this into context:
Continue reading "Notes on the Gartner Summit in Las Vegas, Part 1" »
Wednesday, October 25, 2006
For the longest time, network engineers—particularly those at ISPs and carriers—have kept close watch on link utilization to help them decide how their networks are doing. Once usage levels creep above various thresholds, their answer to provisioning and capacity planning has invariably been "boost the bandwidth," as something of a panacea for network performance problems.
But while increasing link bandwidth can (and does) address certain kinds of network performance issues, it cannot solve all problems. It’s important to understand that all traffic must be transmitted from one point (the sender) to another (the receiver) across a network link. Any complete network transmission involves numerous such pairs of correspondents, as messages move from their original senders to their ultimate receivers, and replies or responses trace their way back in turn from the ultimate receiver to the original sender. But all such transmissions are subject to these three delay components:
Continue reading "Bandwidth is Not a Panacea" »
