When PacketWise analyzes a flow to implement rate controls, one of the factors it takes into account is how aggressively that flow is trying to ramp up in speed.
Being a predictive system, PacketWise continually evaluates and predicts the future needs of flows based on how they are changing today.
Some traffic types are naturally aggressive and will try to burst and demand a lot of bandwidth very quickly. HTTP, FTP, and SMTP are examples.
Some traffic types, such as VoIP, Telnet, and Microsoft NetShow are not anywhere near as aggressive and don't tend to be as demanding for more bandwidth.Additionally, the type of policy you assign will affect how aggressively a flow behaves.
Priority policies are the least aggressive and tend to temper a flow's behavior.
Rate policies with no guaranteed bandwidth will make the flow slightly more aggressive, and burstable rate policies with guaranteed bandwidth will become much more aggressive.This design makes sense -- normally you will be trying to use guaranteed rate to protect the most timid flows such as VoIP or Client/Server, so you want to boost their competitiveness to a level where they can compete better with HTTP and FTP.
It is important to consider, however, that this same characteristic applied to an already aggressive traffic type will make it very greedy. Therefore, you need to exercise extreme caution when adding guaranteed rate to an already aggressive traffic type such as FTP or Microsoft Exchange.
Normally, it is best to use just a plain rate policy with zero K guaranteed for these bursty protocols and reserve the guaranteed rate policies for less-bursty traffic such as Citrix or VoIP.If you must use a guaranteed minimum rate on FTP or similar bursty traffics, it is recommended to use a guaranteed maximum also to prevent the flow from becoming excessively aggressive and taking too much bandwidth.
Another suitable way to cap this type of traffic is to use a partition.
Imported Document ID: 000010953
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