From the course: Cisco CCNP Collaboration 350-801 (CLCOR) Cert Prep: 3 CUCM Call Control, Quality of Service, and Collaboration Applications

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Weighted random early detection

Weighted random early detection

From the course: Cisco CCNP Collaboration 350-801 (CLCOR) Cert Prep: 3 CUCM Call Control, Quality of Service, and Collaboration Applications

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Weighted random early detection

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- [Instructor] When we were discussing our different quality of service mechanisms, remember we talked about congestion avoidance? We said that as a queue starts to fill up, then we can start somewhat randomly discarding packets more and more aggressively as the queue gets deeper and deeper to prevent the queue from filling to capacity. Because if the queue fills to capacity, not only are we discarding all flows trying to go into that queue, we're causing multiple TCP flows to simultaneously go into TCP slow start, something called a global synchronization or TCP synchronization. And the tool that we can use for congestion avoidance is Random Early Detection or RED. Now, this is the industry standard. Cisco has actually improved on this and I'll show you that in just a moment, but first, let's consider the industry standard. As we're trying to go out of an interface or the output queue on a router interface, if we're…

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