[ovs-discuss] [OVN][OpenStack] - scaling broadcast/multicast on tunnels without multicast support?

[Kevin Benton]

>Assuming I understood your statement correctly, with OVN, only one
broadcast packet goes in the tunnel and then it gets replicated in the
hypervisor. So the load is on the CPU instead of the network.

Not quite. What I'm referring to is when you have an overlay that spans
multiple compute nodes. When a broadcast packet needs to be sent to all VMs
in a network, it needs to be duplicated by the sending hypervisor onto a
tunnel to every other compute node with a VM in the network.

On Wed, Jan 13, 2016 at 1:11 PM, Guru Shetty <guru at ovn.org> wrote:

>
>
> On 13 January 2016 at 11:06, Kevin Benton <blak111 at gmail.com> wrote:
>
>> Hi,
>>
>> I looked through the list and see that someone already asked about
>> multicast addresses as a target for VXLAN tunnels[1]. Since it's not
>> supported, what is the suggestion to prevent broadcast/multicast traffic in
>> a tenant's network from wiping out the network due to the duplication cost?
>>
>> This is something the current OVS plugin for Neutron in OpenStack suffers
>> from and it seems OVN will have the same issue as far as I can tell.
>>
>
> Assuming I understood your statement correctly, with OVN, only one
> broadcast packet goes in the tunnel and then it gets replicated in the
> hypervisor. So the load is on the CPU instead of the network.
>
>
>>
>> For example, without severely rate-limiting or completely blocking
>> broadcast/multicast, a tenant network with 100 VMs on it can max out a 10
>> Gbps interface adapter with a 100 mbps broadcast/multicast stream.
>>
>> 1. http://openvswitch.org/pipermail/discuss/2015-December/019632.html
>>
>> Cheers
>> --
>> Kevin Benton
>>
>> _______________________________________________
>> discuss mailing list
>> discuss at openvswitch.org
>> http://openvswitch.org/mailman/listinfo/discuss
>>
>>
>


-- 
Kevin Benton
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