cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
590
Views
5
Helpful
4
Replies

Question about Auto QoS for Video Conferencing Apps

Terence Lockette
Beginner
Beginner

Hello everyone,

We have auto QoS implemented on our switchports since the majority of our ports have phones connected to them.  We also use video conferencing apps such as Teams, Zoom, Exam Med, etc. from the PCs connected behind the phone that's connected to the switch port.  Here are my questions:

Question #1: Will auto qos also mark and prioritize the audio packets coming from these video conferencing apps or will it only tag the audio from the IP phone connected to the port?

Question #2: Can you point me to a guide or resource where I can implement some basic QoS, preferrably LLQ, that will prioritize network control, voice & voice control, video, and all other traffic?

I understand that when implementing QoS other than FIFO, it needs to be configured on all devices in the path of the traffic, so I would need to implement this on 2900/4500, 6800, N9K, and ASA.

 

Thanks all!

Terence

4 Replies 4

Tyson Joachims
Rising star
Rising star

Question #1: Will auto qos also mark and prioritize the audio packets coming from these video conferencing apps or will it only tag the audio from the IP phone connected to the port?

Answer: Auto QoS does not mark the packet. The packet is marked as it is leaving the device. When the switch receives a packet that is marked, it can either choose to accept it, remove it, or re-mark it to a different priority. How you setup the port will determine whether the switch interface honors the marking or not. Using the "auto qos voip cisco-phone" would honor the markings of a cisco phone but would not work if you were running some other brand VoIP solution. In that case you would want "auto qos voip trust". Still if you wanted to honor markings from more than just VoIP traffic, you could do "auto qos trust" and this would honor voice and video markings. This is likely the configuration you would want to go with since you are running both voice and video from both Cisco and non-Cisco devices.

Question #2: Can you point me to a guide or resource where I can implement some basic QoS, preferrably LLQ, that will prioritize network control, voice & voice control, video, and all other traffic?

Answer: There's a lot of resources out there. I really like the series on CBT Nuggets which is a video course discussing all the various forms of QoS. You could also look at the configuration guide for the specific model & code version: https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst2960x/software/15-0_2_EX/qos/configuration_guide/b_qos_152ex_2960-x_cg/b_qos_152ex_2960-x_cg_chapter_011.html

Joseph W. Doherty
Hall of Fame Master Hall of Fame Master
Hall of Fame Master

Q1.  AutoQoS's QoS model has "evolved" overtime, plus, I believe, even when using the same model it might vary from platform to platform because of different QoS features per platform.  So, cannot say what any one instance of autoQoS will do, per platform/IOS-version unless you invoke it.

Q2: Cisco had (has) a reference manual that shows how to implement their 12-class QoS model on different platforms.  Just quickly looked for it, but with changes to Cisco's main site, it hasn't popped up.  They also had (have) a high level entry point for the QoS subject, but trying to find that found https://www.cisco.com/c/en/us/tech/quality-of-service-qos/index.html?dtid=osscdc000283, not what I was expecting, but possibly still a good starting location.

As to other QoS guides or resources, I don't recall seeing any that I really like.  Either current QoS approaches, IMO, are overkill, and/or they don't really convey what should be the goals of QoS, also IMO (notice I'm not using IMHO - laugh).

BTW, "preferrably LLQ", LLQ, generally is available on routers, not switches and it (or PQ) shouldn't really be used by various control traffic types.

Also BTW, here's my suggested all-purpose CBWFQ policy:

policy-map all-purpose
class real-time
!for RT traffic, e.g. VoIP bearer
priority percent 35
class forground
!for truly critial, "lightweight" bandwidth usage, traffic, e.g. VoIP bearer
bandwidth remaining percent 81
fair-queue
class background
!for traffic that is delay insensitive, e.g. database backup, bulk data transfer, some http
bandwidth remaining percent 1
fair-queue
class class-default
!for non-critical delay sensitive traffic, e.g. some http
bandwidth remaining percent 9
fair-queue

So let me ask this question, do I need to add an inbound QoS policy on the interface of the upstream switch/router that is receiving the traffic marked by the QoS policy from the downstream switch, then add an outbound policy for egress traffic to the next upstream device, and follow this process until I hit all devices in the path of the traffic on my network?

What ingress and egress QoS policies can do, or not, again depends on platform, especially different switch series.

On routers, the big difference is ingress policies don't manage buffers while egress polices do.  Both can police and/or mark/remark traffic.

If ingress and egress polices overlap in QoS capabilities, which to use is a decision much like determining whether to use an ingress or egress ACL.

Getting Started

Find answers to your questions by entering keywords or phrases in the Search bar above. New here? Use these resources to familiarize yourself with the community:

Recognize Your Peers