Re: [armd] address resolution requirement from hosts to overlay edge nodes. Any opinion?

[Anoop Ghanwani <[e-mail]>]

On Tue, Feb 14, 2012 at 10:29 AM, AshwoodsmithPeter
<[e-mail]> wrote:

>>That said, there are unicast applications (such as Microsoft's Network
>>Load Balancing) that require multicast at L2, and because they
>>require multicast at L2, such a network would still need to support
>>IP multicast.
>
>>So really, the directory-based approach would be helpful
>>only in a narrow set of circumstances -- no multicast applications
>>including things like NLB.
>
> Anoop, even if you have a good multicast in the underlay network and its being used by things like MS NLB there is still enormous value in eliminating the multicast methods that are used to establish the <c-mac, ip-addr, b-mac tunnel> tripple relationships via some form of database etc.

That's correct, Peter.  As I said in my first response, we have
to solve both problems -- ipaddr->cmac and cmac->bmac/tunnel.
If we solve only one, then the value proposition is significantly
diluted.  As an added benefit, if we solve this problem and there
is no other need for L2 multicast in the network (NLB, directed
broadcast), then the overlay does not need multicast support from
the underlying network.  Requiring IP multicast (especially PIM bidir)
from the network is really a big deal, especially at the kind of
scale that the VXLAN/NVGRE proposals need it.

Anoop