Review of QoS mechanisms

In this video, we're going to take a look at some different quality of service or QoS mechanisms. First, let's identify when or if we might need QoS. One time we might need QoS is in a situation like this where we have a speed mismatch. Notice that we're coming into router R1 on a gig link, but we're going out to the IP WAN on a fast Ethernet link. That's a 10 to 1 speed mismatch. And if traffic is coming in faster than we can send it out, that could cause some congestion on the output interface of that router. Or maybe we don't have a speed mismatch. Instead, we have an aggregation point here. Here we've got an Ethernet switch and all the ports are running at a gig speed, but maybe we've got a bunch of servers coming into the switch, and we're all trying to leave this server farm on a single gig link. We're coming in with multiple gig links and leaving on a single gig link that could cause some oversubscription of the bandwidth and cause congestion, even on a high-speed switch…