HTB download queues in VoIP QoS examples

RouterOS Beginner Basics
1

I’ve been looking through all the VoIP and non VoIP QoS examples here, and noticed interesting thing:

For VoIP people tend to mangle in prerouting, and create both upload and download queue structure.

Non-VoIP examples mangle in postrouting, and don’t create download queues saying QoS on download is pointless


Two questions:

  1. Where’s the truth on efficacy of having download queues on severely asymmetrical link (50/1)? Why some do recommend them?

  2. What is the advantage of mangling in postrouting?

2

This is only my opinion, correct me if i’m wrong.

For VoIP people tend to mangle in prerouting, and create both upload and download queue structure.

If you working with voip, especially if your mikrotik is using nat, as you know the SIP protocol for example using several port for media straming, you will need to mark the connection. Based on the connection mark, you could mark the packet for (QoS) download as well for the upload data stream.

  1. What is the advantage of mangling in postrouting?

If you see on the packet flow diagram, on postrouting you could still mangle any traffic :

  • passing through the router
  • came from local process