Hello, I need to use simultaneously on the same interface the classful
qdisc HTB and the classless qdisc FQ. The rationale is:
- I need to send properly shaped UDP streams to a few remote IP
addresses. For this I'm using htb classes and u32 filters.
- for a few other remote peers I need FQ to be available since I
activated BBR congestion control (ip route change ... congctl bbr)
Questions:
(1) can this be done at all ?
(2) if yes, what are the recommended hierarchy and parameters so
that things go smoothly in the limit of low traffic (neither qdisc
needing a significant fraction of the 1Gbps line rate) ?
I was thinking about
# HTB as root
root@foo:~# tc qdisc add dev eth1 handle 1: root htb
# FQ in a line-rate class
root@foo:~# tc class add dev eth1 parent 1: classid 1:42 htb rate 1gbit
root@foo:~# tc qdisc add dev eth1 parent 1:42 fq
# "n" HTB classes with appropriate rates and individual u32 filters
root@foo:~# tc class add dev eth1 parent 1: classid $id htb rate $rate
root@foo:~# tc filter add dev eth1 parent 1: protocol ip prio
$prio u32 match ip protocol 17 0xff match ip dst $IP/32 flowid $id
Thanks for amending.
(3) In detail, how do the models interact (the token buckets on one
side, and the regular interval timers on the other) ? What happens to
subsequent packets in a paced FQ flow if some get delayed due to
contention: does FQ "catch up" or do packets get offset in the future
?
Thanks in advance,
-Alex
