Control Strategy Overview

Controlling bandwidth allocation for today's traffic diversity is a combination of an art and a learned skill. Packeteer recommends considering the following sequence and points when approaching control features for the first time.

These points apply to situations where you are managing the traffic and applications to and from one location. If you are managing multiple locations with a single PacketShaper, Control Branch Traffic from a Main Site might be more useful.

1. First, develop a useful traffic tree that has traffic classes for the types of traffic you want to control.
   
   
2. Determine which applications are undermining the performance of others.
   
   
3. Identify the applications whose performance is crucial to your organization.
   
   
4. Use the Monitor Traffic window to sort the list by peak bps. Make a list of any class that has peaked to more than 50 percent of the link size.
   
   
5. Using your three lists of applications — those impacting others' performance, those that are important, and those that peak at more than 50 percent of link size — characterize your traffic, categorizing on the basis of importance, size, and sensitivity to latency and jitter.

   It's not necessary to assign a policy to every traffic class. (It's even advisable to avoid over-managing your traffic by creating too many policies and partitions on too many types of traffic.) If you don't assign a specific policy to a class, the class inherits the Inbound or Outbound Default class policy, which is set at the factory as a priority policy with a priority of 3. Although you can change the policy for a Default class, it is not recommended, as this can cause unpredictable results.
   
   Start by managing only your mission-critical traffic and the traffic that impacts others' performance.
   

6. Define partitions and/or policies to protect your important traffic classes. As resources, you can use:
   
   
   • Policy/Partition Guidelines (tables of policies, partitions, and guidelines about when they would and would not be appropriate)
   • Suggested Policies (on-line, in-product policy suggestions)
   • Reserve bandwidth (instructions for protecting bandwidth for the total of all traffic in an application)
   • Insulate users of an application from their peers (instructions to control each application session)
     
     
7. Define partitions and/or policies to contain your important traffic that impacts others or bursts to a large portion of the link. As resources, you can use:
   
   
   • Policy/Partition Guidelines (tables of policies, partitions, and guidelines about when they would and would not be appropriate)
   • Suggested Policies (on-line, in-product policy suggestions)
   • Contain Greedy Business Applications (instructions for limiting an important application)
     
     
8. Define partitions and/or policies to contain your unimportant traffic that impacts others or bursts to a large portion of the link. As resources, you can use:
   
   
   • Policy/Partition Guidelines (tables of policies, partitions, and guidelines about when they would and would not be appropriate)
   • Suggested Policies (on-line, in-product policy suggestions)
   • Limit Total Bandwidth (generic instructions for limiting with a partition)
   • Block Unwanted Traffic (instructions for completely stopping one type of traffic)
     
     
9. Turn on Packeteer 's compression. This feature offers lossless compression and acceleration of network traffic by creating compression tunnels between compression-enabled PacketShapers. No manual configuration is required, as the Packeteer application-specific plug-in architecture automatically selects the algorithm that will yield the best compression ratio for each compressible application or service type.
   
   The compression feature also allows you to define which hosts are allowed to send data through the Xpress tunnel (tunnel discovery host), or restrict the PacketShaper units that can be a tunnel partner (tunnel discovery partner).
   
   
10. When in doubt, follow these rules:

• Don't over manage. Reign in the top pest applications. Protect the top critical applications. Take advantage of compression. And stop.
• If you care about your end users' experience and the traffic has large and long flows, use a rate policy with a minimum guaranteed rate of 0 and no guaranteed rate limit, and assign an appropriate priority for bursting.
• If you care about your end users' experience and the traffic has small and short flows, use a priority policy with an appropriate priority.
• If you do not care about your end users' experience, use a partition with a limit.

Other Useful Considerations

Most protocols are asymmetric, so a policy may fit a profile for one direction of the traffic flow, but a different policy may be required for control of the traffic in the opposite direction.

In general, there are four reasons to control an application:

1. To provision bandwidth for applications that need a set per-session amount to perform (VoIP, Citrix)
2. To protect mission-critical applications
3. To contain bandwidth-greedy applications that impact others
4. To balance necessary and important (but bandwidth-greedy) applications such as HTTP.

The size of your deployment can impact how you implement your control strategy. Both Deployment Size Impact on Control and Control Branch Traffic from a Main Site are helpful.

In certain cases, the location of the server may govern how you manage the traffic. For example, if you are hosting a web server at your site, you may want to give this traffic a higher priority than your users' web-browsing sessions. You can create a customized HTTP traffic class that references the location of this inside server, then use a policy to give this traffic priority. For details about inside and outside servers, see Server Location.

Remember that a policy controls how much bandwidth is allocated to each traffic flow. Do not assign large amounts of guaranteed bandwidth to a traffic class because, as the number of simultaneous sessions increases, you'll run out of bandwidth. To determine if you have exhausted available bandwidth for a class, check the guaranteed rate failures in the Monitor Traffic window. For details, see Monitor Traffic.