VoIP QoS issue using PPPoE from client router

We have a situation like this:

PPPoE SERVER  <---cable--->  PMP450 AP <---- wireless---> PMP450 SM <---cable---> Client Router <---cable---> VoIP Phone

On the Client Router there is a PPPoE Session to our PPPoE Server and all client traffic is sent over the PPP tunnel.

We have setup a high priority channel for this SM but we are getting some loss and artefacts on the voice call.

The AP is not heavily loaded.

Can someone from Cambium please confirm if the AP is able to recnognize the DSCP value on the VoIP / RTP packets and prioritize them when they are encapsulated in PPP packets like in this setup? The RTP stream is using DSCP 46 which should send this data over the high priority channel if it is being recognised properly.



we also have this setup:

PPPoE Server <---cable/wireless--->  ePMP/PMP AP <---- wireless---> ePMP/PMP STA <---cable---> Customer Router (PPPoE Client) <---cable---> Customer LAN

Does the ePMP/PMP recognize the DSCP or the CoS tags that pass encapsulated in the PPP tunnel?

This is a crucial information that I couldn't find in any documentation.



Hi, Cos 01 it's populated in SM and AP?

Hello Tuvix, I don't actually have any CoS setting deployd in my network, this was a question in order to decide if it could be achievable or not.

Speaking of the DSCP, it doesn't recognize the encapsulated priorities, I already tested that.

Canopy PMP(100/430/450) works perfect.

I think ePMP doesn't work when travels inside PPPoE.

To get it work on PMP, without using VLANs needs on both sides (AP/SM) "priority precedence" as "DiffServ Then 802.1p". Then it needs on SM side the traffic be marked with the correct DSCP, and then you need to verify/mark the returned traffic with the same DSCP.

Also, you need to enable on the SM or in the Radius/AP side the "Hi Prority Channel" be enabled, and configured the High Priority Up/Down CIR higher than the bandwidth needed for VoIP.

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Do we know for sure that this (applying DSCP-based QoS to PPPoE traffic being bridged through an SM, not terminated by the SM) does work on the 450 platform?

I intend to test this out, but the reason that I ask is because a similar question was asked about ePMP, and initially the answer from a Cambium rep came back in the affirmative; however, on further pressing the issue, it was revealed that the question was originally misunderstood, and the Cambium rep thought the question was about QoS applied to PPPoE traffic when the SM was the PPPoE client.  That's not what we are talking about.  So I want to make sure that we are crystal-clear on the question at hand.


-- Nathan


Nathana, this is what I confirmed it Works. On PtMP(100/430/450) :

PPPoE Server <---> PtMP AP <---> PtMP SM (Bridge) <---> PPPoE Client

PPPoE Server <---> PtMP AP <---> PtMP SM (NAT Router + PPPoE Client)


Thank you, Roberto.  This is very encouraging.

-- Nathan