Question VOIP and Switches and QOS?

etho201

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I have a router (Peplink Balance 20) with QOS capabilities connected to a Network switch (Ubiquiti US-24 Unifi Switch) that does not have QOS capabilities. The switch is then connected to some VoIP phones as well as some workstations. If I configure QOS on the router will it be effective for the VoIP system or do I need to have a network switch that also has QOS? All cables are CAT 6a.

Here is an image illustrating more clearly what I'm trying to do:

 
QOS at the router is standard, because VOIP traffic that needs attention traverse through the Internet, and Internet goes through the router.

Even if you have VOIP INTRAnet traffic, the distance is so relatively short and much higher bandwidth, that QOS here is not required.
 

etho201

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I guess I was confused since I saw that smart switches and managed switches featured QOS capabilities. Based on your response it seems that QOS in a switch isn't really necessary for most networks -- except for maybe large corporations where there may be a ton of VoIP intranet traffic. Is that right?
 
The only reason you would need QoS even in a large corporate lan was poor design like putting a phone on the same port as a machine that was doing high amounts of traffic.

Modern switches can run every port at say 1gbit up and 1gbit down all at the same time. Since every port can run at maximum speed no data will ever be queued. If there is no queued data there is no need to determine which data needs to go first...ie QoS.

A lot of QoS on switches is not traffic shaping anyway it is traffic marking. It is used to identify which traffic is VoIP traffic so say a router later in the path does not have to have things like lists of IPs. You would then apply traffic shaping rules to some slower path in the chain where you actually do get data queues. Something like a vpn or private network between 2 offices.
 

etho201

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Thanks for everyone's responses, and I do believe the responses were clear enough. It's just there was some contradictory answers on the Cisco forums and the Ubiquiti forums so I felt the need to check elsewhere.

you should configured QoS on all equipments, because if you miss the QoS configuration in one of your equipments (QoS disable), then you are going to miss the 'Marking' of that packet.
Source: Cisco: Where should I configure QoS: router or Switch?

Do you even need QoS on the switches?
QoS : Routers - yes; Switches - No.
Source: Ubiquiti: Unifi Switch US-8-150W - Priorize VoiP traffic?
 
Partially that is because ubiquiti is used for smaller networks where cisco is used for huge enterprise networks.

It is pretty easy to do all your packet market and QoS in the central router if you only have a few hundred devices. If you have 5000 in one campus it get easier to distribute the classification part of qos...ie packet marking out to the end.

The other part of QoS the shaping or policing function is always done on the device that will see the slower line and queued traffic. This tends to be on routers.

So for smaller installs you can do it all on the router. For larger installs it tends to be better to distribute the function.

QoS in a switch is more used when you want to artificially limit traffic rather than priorities it. Say you wanted to limit the user traffic to 50mbps upload rates, that is best done as soon as the traffic comes into the network so it does not put the load on other equipment.
 

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