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8 Advanced Queuing Topics > 8.6 Differentiating Traffic Inside a Queue with WRE...

8.6 Differentiating Traffic Inside a Queue with WRED

When different types of traffic share the same queue, it is sometimes necessary to differentiate between them, as discussed in Chapters 2 and 3. Here, one method used frequently is weighted RED (WRED). WRED is no different than applying different RED profiles for each code point (see Figure 8.11).

Figure 8.11 Multiple RED drop levels in the same queue


To provide a concrete scenario, suppose in-contract and out-of-contract traffic are queued together. While queuing out-of-contract traffic can be acceptable (depending on the service agreement), what is not acceptable is for out-of-contract traffic to have access to queuing resources at the expense of dropping in-contract traffic. Avoiding improper resource allocation can be done by applying an aggressive RED profile to out-of-contract traffic, which ensures that while the queue fill level is low, both in-contract and out-of-contract traffic have access to the same resources. However, when the queue fill level increases beyond a certain point, queuing resources are reserved for in-contract traffic and out-of-contract traffic is dropped. Fi....8.12


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