Hello guys,
does anybody of you have some template for QoS settings? I found plenty of manuals but it’s still not clear how to set prioritization of data flow or why it’s so complicated.
My use case is easy, I just want to have QoS on my WAN port and to be able to use all my devices for: download/upload large files, watch Netflix, stream Spotify and browse pages.
So nothing special - Ideally to have QoS according to services which I’m currently using.
Thanks for any info.
Marek
Hello, the qos you have to adapt to your needs, there are in the forum many related topics and there have also been presentations in the mum here I share a link to you go having some concepts and examples.
https://mum.mikrotik.com/presentations/CZ09/QoS_Megis.pdf
https://mum.mikrotik.com/presentations/US08/janism.pdf
https://mum.mikrotik.com/presentations/IT14/giordano.pdf
Hello I already went through those links but still it’s not really clear how to do prioritization of servises.
Typicaly Youtube, HBO GO, Netflix, Spotify and other streaming services - do I really identify IP addresses in my connections? Why it’s so complicated?
If you imagine, you have 1 Mikrotik router and 1 PC connected to this router. You will start uploading huge files to fast servers and then you aren’t able to use this PC for browsing, because everything is consumed by upload.
There is no simple solution?
The simple solution is to prioritize by DSCP (TOS) value. There is a script on this forum that does it automatically.
See this topic: http://forum.mikrotik.com/t/fasttrack-friendly-qos-script/102401/1
This works OK for applications like VoIP because the writers of those applications usually set the right DSCP value in their packets.
When you have other applications that do not do that correctly, it is the fault of those applications, not of the mechanism.
However, when you merely setup a queue tree as done in the referenced topic, and you make sure your max speed is slightly below the real upload speed of your connection, you already improve matters a lot.
It isn’t complicated. You don’t understand the problem. A router makes decisions based on the contents of the IP header. You are wanting a device to make decisions based on websites and services which are not explicitly in IP headers. While some routers attempt to do what you want, they aren’t good at it (although their marketing departments think they are awesome at it).
The problem is that the Netflix show you want to stream might be hosted at cdn-server83432.thelocalisp.akamai.net. The router has no way to know that the DNS request your computer sent for cdn-server83432.thelocalisp.akamai.net should be part of a prioritized traffic flow.
The other problem is that you are trying to manage bandwidth utilization of inbound (to the router) traffic flows. It is difficult to effectively mange bandwidth utilization on a link in an inbound direction. You have to create queues which prioritize traffic on the egress interface (probably a bridge interface in this case), and that is only moderately effective because the sender can still easily overload the bandwidth-limited link, resulting in packet loss anyway.
The first question to ask is what problem are you trying to solve? Are you experiencing packet loss under certain conditions? What are those conditions? Perhaps rather than prioritizing streaming flows, you could lower the priority of other known flows.
That is a very important point. One aspect of QoS is congestion management, when there is more data to be sent than the bandwidth can cope with. Under these conditions QoS is essentially deciding what data should be sent and what is not sent. It can’t directly do this at the receiving end.
While that is true, the issue of “not being able to view streams while something is being uploaded” is actually not really an inbound QoS problem, it is more of an outbound problem.
Not really QoS usually, it is caused by buffer bloat (the outbound router doing way too much buffering, that buffer is entirely filled with upload packets, and the ACKs on downloads are sent with a lot of delay causing problems in the download direction).
Merely setting up a queue tree on the outbound interface with a max speed less than the actual max speed of the uplink will already help in that case.
Having different priorities on that queue tree can help when e.g. VoIP is in use, but even the local queueing in the router with different queues for different traffic helps most.
E.g. set a “per connection queue” type for the outgoing queue (pcq-upload-default), or “fair queue” (wireless-default). That will mix the ACKs between the upload traffic.
There’s is no simple solution because QoS is a complicated topic. People have been working on this for decades. Routers that promise easy one click solutions don’t work that well, otherwise everyone would include magic solutions on their hardware. CoDel and Cake have improved things for ease of use tremendously, but they aren’t perfect either. CoDel and Cake are being tested on MT (check the development thread).
On MikroTik, a single SFQ queue can mimic some of the benefits of CoDel with regards to fair bandwidth sharing and bufferbloat. Other queue types and combinations of prioritization strategies will require a little more time and effort. However, the more you try to control packets, the more resources will be needed. Many Internet users also forget that service providers have a say on how packets are sent to them. My ISP can throttle everything above 100M at night, regardless of the traffic type or the plan used, and once a buffer is full, packets are dropped.
It is possible to limit Netflix and other streaming sites on MT, but using DSCP is much more efficient. There’s good info on YT about both methods and much more. Note that prioritizing packets that you don’t want delayed or dropped is usually the best strategy (VOIP, conferencing apps), instead of trying to prioritize every packet type with dozens of needless rules.
Hello guys, thanks for your reply, I appreciate and sorry for late reply.
I tried to set something as you recommend and result is:
Please see my configuration in attachment.
Thank you, Marek
router_export.rsc (6.27 KB)
Make sure your upload program in the PC uses a lower priority (DSCP 8 or 16) than the default traffic (normally DSCP 0).
Then use one of the QoS methods that use DSCP (high 3 bits) to determine priority.
What I’ve done is to prioritise small TCP packets on the upload direction. That way if a big upload is taking place the the small TCP “ack” packets relied on for download will still get through. For streaming services you’ll need to look at what upstream control packets are send and do something similar.
DSCP=0 is the lowest possible priority.
Originally that was the case, but as 0 is also the default DSCP value that made it impossible to have below-normal priority e.g. for large transfers.
Therefore in most systems the DSCP values 8 and 16 are used to indicate lowest and one-but-lowest priority, both below the default 0.
When looking at the top 3 bits of DSCP/TOS the priority order is:
7 <= highest
6
5 <= e.g. EF (expedited forwarding), DSCP 46, often used for voice
4
3
0 <= default
2
1 <= lowest
Oops, looks like I’m a little out of date. However doing a quick catch up it looks like that convention is subject to change, with the latest RFC recommending 000001 for LE traffic, this being a value not previously classified. Do you know which convention Mikrotik follows, specifically in the “new-priority=from-dscp-high-3-bits” action? Does that prioritise CS1 above or below default?
MikroTik follows no particular convention at all, I think. Everything RouterOS does is just copying certain fields into others, it is up to the user to assign meaning to that.
The “priority” field is just a field assigned to each packet, it does not change the handling of the packet by itself.
There are some places where it is used:
When you want to use it in a queue, you are on your own. There is no direct way of using the priority field to determine priority in a queue tree.
Linux does support that, and it has a mapping table for it which you would then again fill with that strange sequence.
In RouterOS you need to use packet marks to accomplish that, like this:
/ip firewall mangleadd action=set-priority chain=postrouting comment="From dscp high 3 bits" \
new-priority=from-dscp-high-3-bits passthrough=yes
add action=mark-packet chain=postrouting comment="Priority 0" \
new-packet-mark=prio0 passthrough=no priority=0
add action=mark-packet chain=postrouting comment="Priority 1" \
new-packet-mark=prio1 passthrough=no priority=1
add action=mark-packet chain=postrouting comment="Priority 2" \
new-packet-mark=prio2 passthrough=no priority=2
add action=mark-packet chain=postrouting comment="Priority 3" \
new-packet-mark=prio3 passthrough=no priority=3
add action=mark-packet chain=postrouting comment="Priority 4" \
new-packet-mark=prio4 passthrough=no priority=4
add action=mark-packet chain=postrouting comment="Priority 5" \
new-packet-mark=prio5 passthrough=no priority=5
add action=mark-packet chain=postrouting comment="Priority 6" \
new-packet-mark=prio6 passthrough=no priority=6
add action=mark-packet chain=postrouting comment="Priority 7" \
new-packet-mark=prio7 passthrough=no priority=7
/queue tree
add limit-at=30M max-limit=30M name=inet parent=pppoe-inet
wireless-default
add limit-at=8M max-limit=28M name=inet-p1 packet-mark=prio7 parent=inet \
priority=1 queue=default
add limit-at=8M max-limit=28M name=inet-p2 packet-mark=prio6 parent=inet \
priority=2 queue=default
add limit-at=8M max-limit=28M name=inet-p3 packet-mark=prio5 parent=inet \
priority=3 queue=default
add limit-at=8M max-limit=28M name=inet-p4 packet-mark=prio4 parent=inet \
priority=4 queue=default
add limit-at=8M max-limit=28M name=inet-p5 packet-mark=prio3 parent=inet \
priority=5 queue=default
add limit-at=8M max-limit=28M name=inet-p6 packet-mark=prio0 parent=inet \
priority=6 queue=pcq-upload-default
add limit-at=8M max-limit=28M name=inet-p7 packet-mark=prio2 parent=inet \
priority=7 queue=default
add limit-at=8M max-limit=28M name=inet-p8 packet-mark=prio1 parent=inet \
queue=default
Note that the mark “prio2” refers to “top 3 bits of DSCP have value 002” here and that this is then translated into priority 7 for the queues.
It is a bit confusing that in the packet priority field higher value generally indicates higher priority, while in the queue tree priority field lower values is higher priority.
Here they are mapped by a series of rules, while in Linux itself you could do that with a single “priomap” table.
pardon me if a bit out of main topic, may i ask about bandwith allocation on above queue,
if we sum total limit at then they will exceed max limit, will the exceed will be dropped since we have set the max limit 30M only?
thank you