I am wondering if possible to do QOS (or similar action) inside vpn tunnel to a cloud server. the goal is to reserved bandwith for voip traffic.

I read that you can with GRE and other people said, you cannot have qos over the internet. Your ISP do not honor qos (only with mpls or contract).

So, if I build a vpn tunnel to another remote site, is there way to manage the qos on the local network and thru the vpn tunnel for voip traffic.

ah yes, btw I do not have access to the cisco ASA 5506 on the customer's network. I think I am stuck. I plan to build a vpn tunnel (for dev) with a raspberrypi.

thank you all,

  • "ah yes, btw I do not have access to the cisco ASA 5506 on the customer's network." The QoS concept question is on-topic, but, unfortunately, questions about networks you do not directly control, and questions about consumer-grade devices and host/server configurations are off-topic here, so we will not really be able to help with the design, configuration, or implementation of your solution.
    – Ron Maupin
    Commented Apr 1, 2019 at 5:08

1 Answer 1


Possible? Generally, yes. However, you need to consider the tunnel outside as well. How effective QoS works depends on a large number of parameters only some of which you have control over.

QoS inside a tunnel makes only sense when the tunnel traffic can't be congested from the outside - you'll need to reserve bandwidth for the tunnel itself as well. The downside is that you can't differentiate between high-priority traffic and low-priority traffic from the outside. You might want to consider running a separate tunnel for each priority.

Of course, all this is limited by the service quality between tunnel endpoints - effectively, you can only handle congestion based on a nominal or minimum bandwidth you've got between the endpoints. Additionally limited bandwidth during high-traffic times at your ISP can't be handled without their cooperation.

  • thx, and about marking packets with DSCP, I have a better chance to improve quality of voip traffic ? my goal is provided the best quality site-to-site on most network. Commented Mar 31, 2019 at 14:49
  • @svi08wi0er92u30r How you implent QoS doesn't matter - it's up to what your devices support - DSCP, by source/destination IP, protocol, source/dest port, route, ...
    – Zac67
    Commented Mar 31, 2019 at 15:29
  • 1
    PS: DSCP flags are usually ignored on the Internet, so they won't work on the tunnel outside across WAN.
    – Zac67
    Commented Dec 16, 2019 at 15:50

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