Re: [armd] datacenter reference architecture draft

Joel, 

See comments inserted below:

> -----Original Message-----
> From: armd-bounces@ietf.org [mailto:armd-bounces@ietf.org] On Behalf Of
> Joel jaeggli
> Sent: Monday, October 31, 2011 1:29 PM
> To: Manish Karir
> Cc: armd@ietf.org
> Subject: Re: [armd] datacenter reference architecture draft
> 
> 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.
[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? 

> 
> 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.

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

> 
> 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.

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

> 
> On 10/28/11 09:01 , Manish Karir wrote:
> >
> > 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
> > -----------------------------------------
> > 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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