Getting the most for your Internet dollar
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If you are charged with deploying bandwidth-hungry Internet applications, the pressure is on to deliver high-quality service while keeping network expenses to a minimum.
You could simply keep increasing the size of your companies' Internet access pipes to keep up with bandwidth demands, but not if your goal is to keep costs down. Bandwidth, after all, isn't cheap.
MCI WorldCom's UUNET division, for example, charges $1,295 per month for a burstable T-1 service if you average 128K bit/sec of usage. If you average between 384K and 512K bit/sec of usage, the charge jumps to $2,750 per month. These are list prices, and you can expect 5% to 15% discounts if you sign one- to three-year contracts, but total circuit costs still add up fast.
The alternative, of course, is to better manage the pipes you already have. With the onslaught of new bandwidth management products in the past six to 12 months, business users have more choices than ever to choose from.
Packeteer and Xedia were some of the first vendors to introduce bandwidth management devices. But now users have other choices, including products from Allot Communications, NetReality and Elron Software, to name a few.
Basically, these products let you dedicate portions of your Internet access trunks to certain types of traffic, specific IP addresses or URLs. The ability to divide bandwidth lets you deploy applications such as SAP over IP-based virtual private networks (VPN) because you can dedicate capacity to SAP traffic at the expense of traffic coming from, for example, ESPN's home page.
Northwest Missouri State University started looking at bandwidth management products because it wanted the ability to ensure that business applications have the bandwidth they need, says Jonathan Sloop, a client/server technician at the Maryville, Mo., college. The university next semester plans to add four Web-based courses to its curriculum.
The school has been testing Elron's Bandwidth Optimizer NT-based management system to guarantee the network will have enough bandwidth to support students that sign up for Web-based classes. The product could also help keep Internet games from hogging the network when classes aren't in session, Sloop says.
Products such as Bandwidth Optimizer typically sit directly behind an access router and police incoming and outgoing Internet traffic based on policies that a network manager sets up. But to ensure Citrix traffic on a VPN gets 128K bit/sec worth of bandwidth, for example, you would have to deploy a management device at every endpoint.
While the premise behind bandwidth management devices is the same, they have some proprietary technology that essentially makes it impossible for you to deploy multiple vendor's devices.
For example, Littleton, Mass.-based Xedia's AccessPoint bandwidth management devices support class-based queuing (CBQ) and the Internet Engineering Task Force's pending Differentiated Services (Diff-Serv) specification. Queuing lets you set priorities or establish different classes of service on your network. Using Xedia's management tool, which is SNMP-based, you can carve your connection to the Internet into three different service classes.
Diff-Serv then allows you to tag certain types of traffic based on a predefined queuing class system. For example, Diff-Serv lets you mark all Citrix, SAP or voice traffic as first-class traffic. This traffic always flows to the queue you have indicated as the highest priority queue - most likely the queue with the largest amount of bandwidth.
When one queue becomes full, AccessPoint either drops those packets and resends them when the congestion has subsided, or you can set up the device to bump second- and third-class traffic before dropping any first-class traffic.
Packeteer in Santa Clara, Calif., on the other hand, has been using TCP rate control to let customers guarantee bandwidth on IP networks. TCP rate control lets you assign transmission rates for each traffic class you define. Without resorting to queues that some say cause network latency, Packeteer's PacketShaper 2000 lets you set policies that are primarily based on traffic type but can also take into account IP addresses and URLs.
Products from some vendors, such as Allot, NetReality and Amplify.net, combine queuing and TCP rate control with unique twists. NetReality's WiseWan Enterprise device and network managed software use adaptive fair weighted queuing. While similar to CBQ, adaptive fair weighted queuing deals with overloaded queues differently. An end user on a WiseWan network will be notified if his traffic is being stored because his given queue is overloaded. Other queuing technology doesn't provide such end-user notification.
Amplify.net is combining its CBQ implementation with a SQL database. The company's iSurferRanger.ec bandwidth management device doesn't process policy information like competitors' products. Instead, iSurferRanger.ec consults a SQL database for directions on dealing with a particular user's traffic. Amplify.net claims moving the processing job to a database server speeds up policy enforcement on an IP network.
Each bandwidth management vendor can tout a unique plus, but the trend is pushing the industry away from interoperability. Standards organizations are trying to address this problem.
The IETF has several bandwidth management specifications in the works, such as Resource Reservation Protocol, Multi-protocol Label Switching and Diff-Serv. But the industry isn't ready to fully adopt these protocols as the best and only ways to address bandwidth management or quality of service over an IP backbone.
So you have options, but pick and choose carefully, because you may be stuck with a single-vendor solution for longer than you might like.
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