10.1 Queuing
10.1.4 Choosing a cisco IOS queuing option

Determining the best Cisco IOS queuing option for your traffic needs involves the following general guidelines (as represented in the Figure):

  1. Determine whether the WAN is congested. If no traffic congestion exists, there is no need to sort the traffic—it is serviced as it arrives. However, if the traffic load exceeds the transmission capacity for periods of time, then one of Cisco's IOS-queuing options may be the solution.
  2. Decide whether strict control over traffic prioritization is necessary and whether automatic configuration is acceptable. Proper queuing configuration is not necessarily a simple task. To effectively perform this task, the network manager must study the types of traffic using the interface, determine how to distinguish them, and decide their relative priority. This done, the manager must install the filters and test their effect on the traffic. Traffic patterns change over time, so the analysis must be repeated periodically.
  3. Establish a queuing policy.
    A queuing policy results from the analysis of traffic patterns and the determination of the relative traffic priorities discussed in Step 2.
  4. Determine whether any of the traffic types you identified in your traffic pattern analysis can tolerate a delay.

Queuing: Return Policy
For queuing to be pertinent, the answering router should have the same queuing policy.