Subject: [armd] datacenter reference architecture draft

From: Manish Karir <[email-masked]>
Date: Fri, 28 Oct 2011 12:01:52 -0400

The following draft was submitted to hopefully help focus the ARMD discussion around a common architecture.

Comments and feedback are welcome.  The goal of the writeup really is to abstract away specific datacenter designs
each of which focuses on solving a particular application/traffic pattern by trying to talk about what is common between 
the various designs.  Hopefully this will help some of the very varied discussion that has taken place in this WG so far.

Thanks.
-manish

http://www.ietf.org/id/draft-armd-datacenter-reference-arch-01.txt
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Filename:	 draft-karir-armd-datacenter-reference-arch
Revision:	 00
Title:		 Data Center Reference Architectures
Creation date:	 2011-10-24
WG ID:		 Individual Submission
Number of pages: 11

Abstract:
  The continued growth of large-scale data centers has resulted in a
  wide range of architectures and designs.  Each design is tuned to
  address the challenges and requirements of the specific applications
  and workload that the data is being built for.  Each design evolves
  as engineering solutions are developed to workaround limitations of
  existing protocols, hardware, as well as software implementations.

  The goal of this document is to characterize this problem space in
  detail in order to better understand if there is any gap in making
  address resolution scale in various network designs for data
  centers.  In particular it is our goal to peel back the various
  optimization and engineering solutions to develop generalized
  reference architectures for a data center.  We also discuss the
  various factors that influence design choices in developing various
  data center designs.
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From: Joel jaeggli <[email-masked]>
Date: Mon, 31 Oct 2011 11:28:52 -0700

so, I looked at it for a while...

I'm a bit mystified by 3.4.1-3.4.4

we've already arrived I guess at what we conclude is the ideal topology,
and a particular model of mobility.

When faced with this choice and a desire to constrain both the
complexity and the diameter failure domain one response is to not make
the network the arbiter of mobility, e.g. move that to provisioning or
the application layer. the result is a lot closer to 3.4.1 than it is
the others.

One of he problems I have with managing a large l2 domain, particularly
one constructed as an overlay is that there's effectively no upper bound
appart from physics and good taste for how far it can spread, first they
want across the rack, the module, then across the whole datacenter, then
to the adjacent datacenter, across the country, to other cloud
providers, etc. if you  constrain it sufficiently small that
availability is not a design consideration (1 or 2 switches is big l2
domain) then it doesn't become a dependency.

Insisting that ip addresses move around with virtualized machines is one
way to view the world but it not the only way. nor is constraining
tenets to common l2 buckets the only way to segment applications from
each other, the hosts for the virtual machines can just as well be (are)
policy enforcement points.

On 10/28/11 09:01 , Manish Karir wrote:
> _______________________________________________
> armd mailing list
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> https://www.ietf.org/mailman/listinfo/armd
>

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From: Linda Dunbar <[email-masked]>
Date: Mon, 31 Oct 2011 19:32:56 +0000

Joel, 

See comments inserted below:

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]] On Behalf Of
> Joel jaeggli
> Sent: Monday, October 31, 2011 1:29 PM
> To: Manish Karir
> Cc: [email-masked]
> Subject: Re: [armd] datacenter reference architecture draft
> 
[Linda] Are you saying that the data center which you manage prefers 3.4.1 or majority of data centers should be 3.4.1? 

> domain) then it doesn't become a dependency.

[Linda] Do you mean that simply not let L2 go beyond ToR switches?  

> policy enforcement points.

[Linda] Can you elaborate this a bit more on "the hosts for VM can just as well be policy enforcement points"? 

> > Comments and feedback are welcome.  The goal of the writeup really is
> to abstract away specific datacenter designs
> > each of which focuses on solving a particular application/traffic
> pattern by trying to talk about what is common between
> > the various designs.  Hopefully this will help some of the very
> varied discussion that has taken place in this WG so far.
> >
> > Thanks.
> > -manish
> >