I am working on a bash utility that will use several aspects of the tc Linux command line utility to emulate various network conditions. I have successfully constructed several qdisc hierarchies, one each for HTB bandwidth control, NetEM delay and packet manipulation, and TBF rate control, as well as combined handlers for HTB-NetEM, and TBF-NetEM Where I am struggling is in combining the three into a single structure, for cases in which I need to control all of these factors on a single connection. This is what I have so far:
sudo tc qdisc add dev $interface root handle 1:0 htb
sudo tc class add dev $interface parent 1:0 classid 1:1 htb #htb args
sudo tc qdisc add dev $interface parent 1:1 handle 10:0 tbf #tbf args
sudo tc qdisc add dev $interface parent 10:1 handle 101:0 netem #netem args
Because of my smaller scope cases, I know that the problem does not lie in the syntax of my inputs, but likely in the structure of my tc qdiscs and classes. When I attempt to run these commands together with rate and bandwidth shaping arguments (10 and 15 Mbit/s respectively) in both ethernet ports of my bridge, no change to the bandwidth of an iperf test is shown, in TCP or UDP. Any advice would be appreciated.
Here are my other working compound structures, in case they might help:
HTB and NetEM:
sudo tc qdisc add dev $interface root handle 1: htb
sudo tc class add dev $interface parent 1:0 classid 1:1 htb #htb args
sudo tc qdisc add dev $interface parent 1:1 handle 10:0 netem #netem args
TBF and NetEM:
sudo tc qdisc add dev $interface root handle 1:0 tbf #tbf args
sudo tc qdisc add dev $interface parent 1:1 handle 10:0 netem #netem args
Best Answer
What you want is not HTB/TBF but HFSC.
http://man7.org/linux/man-pages/man7/tc-hfsc.7.html
You can attach netem to the leaf classes.
Here is a sample script to get you started..
This creates a 100mbit class, 50mbit of which is in the default class (but can burst up to 100mbit) whilst the other class permits a realtime requirement so that 1500 byte packets must leave the queue within 50ms, the maximum rate of this class is 10mbit at all times.
Finally we added a leaf qdisc onto that class which actually delays packets leaving the queue by 150ms.
Traffic into the realtime class is selected on the basis of it having a source port 22 attribute (so all ssh traffic).