Need a sanity check on a queue tree

RouterOS General
1

I’ve been building queue trees for ages, but I’m second guessing myself on this one, perhaps because it seems too simple to work as expected.

Total bandwidth is 50/10. On the SIP queues, I’m not 100% sure if I need to specify bandwidth at all. I’m thinking that if the sum of the other queues has a limit-at of 36/6, then SIP, at a higher priority will be able to use up to 4Mbit/s at all times.

I’m using round numbers for the sake of readability, they will be changed to match reality once we install this and are able to run some bandwidth tests to find the actual throughput.

/queue tree
add max-limit=50M name="Total Down" parent=global queue=default
add max-limit=10M name="Total Up" parent=global queue=default
add name="SIP Down" packet-mark=SIP_Down parent="Total Down" priority=5 queue=default
add name="SIP Up" packet-mark=SIP_Up parent="Total Up" priority=5 queue=default
add limit-at=10M max-limit=50M name="Data Down" packet-mark=Data_Down parent="Total Down" queue=pcq-download-default
add limit-at=2M max-limit=10M name="Data Up" packet-mark=Data_Up parent="Total Up" queue=pcq-upload-default
add limit-at=36M max-limit=50M name="Guest Down" packet-mark=Guest_Down parent="Total Down" queue=pcq-download-default
add limit-at=4M max-limit=10M name="Guest Up" packet-mark=Guest_Up parent="Total Up" queue=pcq-upload-default

Thanks!

2

It makes sense to me - just be careful never to guarantee too much bandwidth to the other queues because a priority 8 queue below limit-at will get service before a priority 1 queue above its limit-at (or also I assume one with no CIR defined).

You may also want to put a max-limit on the SIP queues so they don’t have the ability to starve the rest of your applications if something strange like a packet flood comes in matching this queue. VoIP isn’t really a high bandwidth application - it just requires low jitter, and in the case of G711-encapsulated faxes, low latency. (T.38 can stand over 200ms latency - I’ve seen it work flawlessly over satellite links) 2M should be quite enough for a VoIP queue’s max-limit… so long as it ONLY matches SIP and RTP. If you’re matching IP addresses, then make sure that TFTP between the phone and SIP service doesn’t get into the SIP queue.