# QoS on Cisco 4500-X **URL:** \ **Category:** Quality of Service\ **Created:** [May 11, 2020, 10:52pm UTC](https://forum.networklessons.com/t/qos-on-cisco-4500-x/11162 "2020-05-11T22:52:46Z")\ **Posts on this page:** 1\ **Showing post:** 2
**Author:** ![lagapidis](https://cdn-forum.networklessons.com/user_avatar/forum.networklessons.com/lagapidis/32/4949_2.png) [@lagapidis](https://forum.networklessons.com/u/lagapidis)\ **Post date:** [May 15, 2020, 9:48am UTC](https://forum.networklessons.com/t/qos-on-cisco-4500-x/11162/2 "2020-05-15T09:48:17Z")
Hello Aaron I’ll try to address your concerns so that you can have an idea of how to proceed from here. > [@skygremlin](#): > > I can set class-maps and Policy-maps, but can either do Priority or bandwidth inside the Policy-\>Class. This is how policy maps are set up. You cannot configure both priority and bandwidth, but either one. However, I believe what you are looking for is to configure a maximum allowed bandwidth for the priority queue. That can indeed be configured simultaneously and it is achieved using the policing feature. > [@skygremlin](#): > > For example the 8-class QoS strategy… Consider looking at the 4-class QoS strategy, as that provides a more suitable scenario for your situation, since you don’t need so many QoS classes. > [@skygremlin](#): > > Voice: Marked with EF and limited to 10 percent of link bandwidth in a strict-priority queue > – Is this telling me that traffic marked as EF will get Priority 10% and only 10% of link bandwidth > > Multimedia conferencing (Interactive video): Marked with AF41 or sometimes as EF and limited to 23 percent of link bandwidth in a strict-priority queue > – Is this telling me that traffic marked as AF41 will get 23% and only 23% of link bandwidth OK there are a couple of issues here. If your voice is marked with EF, and your interactive video is also sometimes marked with EF, then you must find a way to differentiate them. This can be done either by matching an access list for particular ports (rather than QoS markings), or by changing the QoS markings on those particular packets. More on the latter later. You can also use what is known as multi-level priority queues, which are further described in the following Cisco documentation. It may however not be supported on your platform: > **[QoS: Congestion Management Configuration Guide - Multi-Level Priority Queues...](https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/qos_conmgt/configuration/xe-16/qos-conmgt-xe-16-book/qos-conmgt-multilevel-pq.html)** > > QoS: Congestion Management Configuration Guide -Multi-Level Priority Queues Now does that mean that only 23% will be used? There is what is known as an implicit policer implemented in these cases, so yes. Take a look at this post which may give you some more information about this: > [@QoS LLQ (Low Latency Queueing) on Cisco IOS](https://forum.networklessons.com/t/qos-llq-low-latency-queueing-on-cisco-ios/1817/43): > > Hello Michael Let’s use this diagram from the lesson to help us out: [image] Notice that the interface is a GigabitEthernet interface, and that the priority queue is set to 50% of the total bandwidth. Now remember, if there’s no congestion, the above queues are non-existent, and all traffic is served immediately. Now let’s assume we have congestion over an extended period of time, and we have a lot of priority traffic arriving at the interface. That priority traffic will go into the prior… > [@skygremlin](#): > > If I have traffic entering the switch marked as EF can I change that to something else like CS4 or AF41 via: ACL → class-map → Policy-map config. Before it hits the EF class-map? We have Zoom running and currently the app is tagging traffic as EF. I’d like to have my Voice take precedence over Zoom all the time… If you create a policy map that identifies the Zoom traffic (using IP address or port numbers for example) and place it incoming on the appropriate interface, you can use that policy map to change the QoS marking to whatever you like. Then they will reach the EF class map with the appropriate marking and you can treat them differently from your other traffic since you can now differentiate between them. For most of the other questions, take a look at the following lesson: > **[QoS LLQ (Low Latency Queueing) on Cisco IOS](https://networklessons.com/quality-of-service/qos-llq-low-latency-queueing-cisco-ios)** > > LLQ (Low Latency Queueing) adds a priority queue to CBWFQ (Class Based Weighted Fair Queueing). We explain how to configure LLQ on Cisco IOS. I hope this has been helpful! Laz --- _[View the full topic](https://forum.networklessons.com/t/qos-on-cisco-4500-x/11162)._