Question about Network rate.

[SviridoffA]

Can anyone help me please? I need clarification about network rate I’m using KVM, bridges, ACS 4.19.3, with the entire infrastructure on Ubuntu 24.04. When I set the Network rate value in the Network offering, does this value apply to all network traffic, both internal and to public ? Or does it only apply to incoming and outgoing traffic between the guest and the public network? And if this restriction applies to the internal traffic of the guest network, how can I properly set a limit only for traffic to the public network?

[rajujith]

@SviridoffA
'vm.network.throttling.rate'.The rate is set on global settings applied to the Instance's default interface at the instance level. This can also be set on the compute offering; if set, it takes precedence.
'network.throttling.rate' set on global settings gets applied on the guest interface of the VR., This can be set to the network offering as well; if set, this takes precedence. Public interfaces are not throttled currently ( as per the docs), but it is throttled by means of settings on the guest interface of the VR.
Both are applied to either direction.

[SviridoffA]

Thanks @rajujith for your clarifications. I was expecting this working model but just wanted to be sure that the network offering rate does not affect internal traffic between VMs. I also checked this practically with iperf, and it’s not affected. Digging a bit deeper, I saw that this limit is only applied to the router's vnet interface via tc. Maybe it will be useful for someone.)

[rajujith]

@SviridoffA you can see the rate limit on the KVM domain XML as well as on tc.

example:

 </interface>
    <interface type='bridge'>
      <mac address='1e:00:7c:00:00:04'/>
      <source bridge='breth1-51'/>
      <bandwidth>
        <inbound average='89600' peak='89600'/>
        <outbound average='89600' peak='89600'/>
      </bandwidth>
      <target dev='vnet13'/>
      <model type='virtio'/>
      <link state='up'/>
      <alias name='net2'/>
      <rom bar='off' file=''/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
    </interface>

tc -p class show dev vnet13
class htb 1:1 root leaf 2: prio 0 rate 716800Kbit ceil 716800Kbit burst 1433b cburst 1433b

[SviridoffA]

Oh, that's cool, thanks for this tip!)