Apologies, when I said "in guests" I meant only guests I was iper'fing. To clarify: guests on different but virtually identical hosts - iperf3 between such guests. What should a "typical" _tc_ look like with libvirt doing bandwidth management? Seems that libvirt does QoS on the hosts - this is with a single net bandwidth'ed: -> $ tc -s -d class show dev nm-bridge1011 class htb 1:1 root rate 4882Mbit ceil 4960Mbit linklayer ethernet burst 1601b/1mpu 0b cburst 1626b/1mpu 0b level 7 Sent 9559833379 bytes 10652255 pkt (dropped 0, overlimits 594941 requeues 0) backlog 0b 0p requeues 0 lended: 0 borrowed: 0 giants: 0 tokens: 39 ctokens: 39 class htb 1:2 parent 1:1 leaf 2: prio 0 quantum 52083 rate 4882Mbit ceil 4960Mbit linklayer ethernet burst 1601b/1mpu 0b cburst 1626b/1mpu 0b level 0 Sent 9559833379 bytes 10652255 pkt (dropped 0, overlimits 641156 requeues 0) backlog 0b 0p requeues 0 lended: 10399228 borrowed: 0 giants: 0 tokens: 39 ctokens: 39 and yet... What might be not/happening here? thanks, L.