Re: [armd] soliciting typical network designs for ARMD

[Vishwas Manral <[e-mail]>]

Hi Linda,

The data packets can be tunnelled at the ToR over say a GRE packet and the
core is a Layer-3 core (except for the downstream ports). So we could have
encapsulation/ decapsulation of L2 over GRE at the ToR.

The very same thing can be done at the hypervisor layer too, in which case
the entire DC network would look like a Layer-3 flat network including the
ToR to server link and the hypervisor would do the tunneling.

I am not sure if you got the points above or not. I know cloud OS companies
that provide the service and have big announced customers.

Thanks,
Vishwas
On Tue, Aug 9, 2011 at 11:51 AM, Linda Dunbar <[e-mail]> wrote:

> Vishwas,
>
> In my mind the bullet 1) in the list refers to ToR switches downstream
> ports (facing servers) running Layer 2 and ToR uplinks ports run IP Layer 3.
>
>
> Have you seen data center networks with ToR switches downstream ports (i.e.
> facing servers) enabling IP routing, even though the physical links are
> Ethernet?
> If yes, we should definitely include it in the ARMD draft.
>
> Thanks,
> Linda
>   On Tue, Aug 9, 2011 at 12:58 PM, Vishwas Manral <[e-mail]>wrote:
>
>> Hi Linda,
>> I am unsure what you mean by this, but:
>>
>>    1. layer 3 all the way to TOR (Top of Rack switches),
>>
>> We can also have a heirarchical network, with the core totally Layer-3
>> (and having seperate routing), from the hosts still in a large Layer-3
>> subnet. Another aspect could be to have a totally Layer-3 network.
>>
>> The difference between them is the link between the servers and the ToR.
>>
>> Thanks,
>> Vishwas
>>   On Tue, Aug 9, 2011 at 10:22 AM, Linda Dunbar <[e-mail]>wrote:
>>
>>> During the 81st IETF ARMD WG discussion, it was suggested that it is
>>> necessary to document typical data center network designs so that address
>>> resolution scaling issues can be properly described. Many data center
>>> operators have expressed that they can't openly reveal their detailed
>>> network designs. Therefore, we only want to document anonymous designs
>>> without too much detail. During the journey of establishing ARMD, we have
>>> come across the following typical data center network designs:
>>>
>>>    1. layer 3 all the way to TOR (Top of Rack switches),
>>>    2. large layer 2 with hundreds (or thousands) of ToRs being
>>>    interconnected by Layer 2. This design will have thousands of hosts under
>>>    the L2/L3 boundary router (s)
>>>    3. CLOS design  with thousands of switches. This design will have
>>>    thousands of hosts under the L2/L3 boundary router(s)
>>>
>>> We have heard that each of the designs above has its own problems. ARMD
>>> problem statements might need to document DC problems under each typical
>>> design.
>>> Please send feedback to us (either to the armd email list  or to the ARMD
>>> chair Benson & Linda) to indicate if we have missed any typical Data Center
>>> network designs.
>>>
>>> Your contribution can greatly accelerate the progress of ARMD WG.
>>>
>>> Thank you very much.
>>>
>>> Linda & Benson
>>>
>>
>