queue tree - how to split bandwidth and enable borrows and lends of unused bandwidth

RouterOS General
1

Hello,

I am using queue trees (marking packets via mangle), and it works like a charm, shaping works well and accurate. But now, I wand to enable using the unused bandwidth - I believe mikrotik calls this borrows and lends here https://wiki.mikrotik.com/wiki/Manual:Queue:

borrows (read-only/read-only) : packets that passed queue over its “limit-at” value (and was unused and taken away from other queues)
lends (read-only/read-only) : packets that passed queue below its “limit-at” value OR if queue is a parent - sum of all child borrowed packets

Let’s assume I have 200Mbit connection on eth1, and I have 100Mbit for eth2 and 100Mbit for eth3. Mangling packets, set max-limit, everything works well and both have guaranteed and reserved 100Mbit.

/queue tree print
Flags: X - disabled, I - invalid 
 0   name="0Up" parent=global packet-mark=0Up limit-at=0 queue=default-small 
     priority=8 max-limit=100M burst-limit=0 burst-threshold=0 burst-time=0s 
     bucket-size=0.1 
 1   name="0Down" parent=global packet-mark=0Down limit-at=0 queue=default-small 
     priority=8 max-limit=100M burst-limit=0 burst-threshold=0 burst-time=0s 
     bucket-size=0.1 
 2   name="1Up" parent=global packet-mark=1Up limit-at=0 queue=default-small 
     priority=8 max-limit=100M burst-limit=0 burst-threshold=0 burst-time=0s 
     bucket-size=0.1 
 3   name="1Down" parent=global packet-mark=1Down limit-at=0 queue=default-small 
     priority=8 max-limit=100M burst-limit=0 burst-threshold=0 burst-time=0s 
     bucket-size=0.1

Now let’s assume that eth3 is not used that day at all, and eth2 is used very intensively at maximum speed - then it is limited to its 100Mbit, while the other 100Mbit of the 200Mbit line is unused. The goal is to make the queue use the unused 100Mbit of eth3, but when there is traffic on eth3, give it its quaranteed speed up to 100Mbit. Without eth3, I want 200Mbit for eth2, when eth3 is downloading 30Mbit, eth2 will get 170Mbit, when eth3 is downloading at max speed, both will get their 100Mbit etc.

I tried do set max-limit=200M and limit-At=100M on both queues, but it doesnt work. I tried to add their parent queue with max-limit=200M, but it does not work either.

What I am doing wrong?
thank you

2

Looking at the literature
you would put the limit-at rate to the max you would want them to have during the day so a CIR of 100M then you would put max limit at 200M. the parent for all these queues also needs to have the max limit for the whole link. it will then use unused bandwidth from one location that is available.