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

[Kevin Benton]

It could be anything. A tenant could use multicast to send a video stream
to a bunch of other encoding servers for example.

On Wed, Jan 13, 2016 at 4:11 PM, Gal <gal.sagie at gmail.com> wrote:

> Hi Kevin,
>
> Can you please share what kinds of broadcast/multicast traffic you usually
> see ? (That is not ARP or DHCP)
>
> Thanks,
> Gal
>
> נשלח מה-iPhone שלי
>
> ‫ב-13 בינו׳ 2016, בשעה 21:14, ‏‏Kevin Benton ‏<blak111 at gmail.com> כתב/ה:‬
>
> >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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>
>


-- 
Kevin Benton
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