Subject: Re: [armd] Updated ARMD Charter and Milestones

From: Jari Arkko <[email-masked]>
Date: Wed, 26 Jan 2011 23:26:04 -0800

Linda,

Thanks for suggesting text. I have a few comments on this. The main
comment is that I do not think we are ready to create a working group
that actually develops the solutions. I would like to see the "document
the scaling characteristics" stage successfully completed first before
chartering any work on solutions. This is not to say that we can't do
the work -- even in the schedule you outline in the milestones -- but at
least I personally have some trouble committing to the solution part
before I fully understand the current characteristics.

So from my perspective I'd remove the solution milestones and text
discussing that part of the work. I would also change the objectives as
follows:

(1）To document the scaling characteristics of ARP (IPv4) and ND (IPv6)
with respect to increasing numbers of hosts in data centers, (2) to
identify limitations of ARP and ND in such environments, (3) provide
design recommendations intended to minimize issues associated with the
identified limitations, and (4) to develop appropriate solutions to
better support data centers with large number of hosts.

=>

（1）To document the scaling characteristics of ARP (IPv4) and ND (IPv6)
with respect to increasing numbers of hosts in data centers and (2)
provide operational recommendations intended to minimize issues
associated with the limits inherent in these characteristics.

(Just my $0.02, of course, not wearing any hats at the moment.)

Jari

---

From: Thomas Narten <[email-masked]>
Date: Thu, 27 Jan 2011 09:18:20 -0500

Based on the thread of the last week, I think it's misleading to
restrict the charter of this work just to ARP and ND.

It seems clear to me that this is also about VLANs, how they are
typically deployed in a large data center, and how migration of
servers from one part of the data center to another is changing
communication assumptions that have been true in the past (e.g., a
single IP subnet no longer resides just within a single aggregation
switch, but is stretching a VLAN across the data center in new ways).

My point is, the focus on ARP and ND is too narrow. The overall
problem stems from L2 practices that are more complex than just
treating the entire data center as one big IP subnet. In fact, it is
being treated as one big L2 broadcast domain, with VLANs overlaid on
that domain in ways that are changing. As the pattern for how VLANs
are deployed in practice, that impacts the traffic patterns across the
data center. It is those changing patters that appear to be the root
cause of the scaling problems being blamed on ARP.

I also support chartering only the documentation of the problem at
this time.

Thomas

---

From: Hares Susan <[email-masked]>
Date: Thu, 27 Jan 2011 02:28:38 -0500

Jari:

Thank you for the feedback on the objectives.  We'll wait and see what Ralph
Droms has to say.

Sue

-----Original Message-----
From: Jari Arkko [mailto:[email-masked]]
Sent: Thursday, January 27, 2011 2:26 AM
To: Linda Dunbar
Cc: [email-masked]; [email-masked]; 'Hares Susan'
Subject: Re: Updated ARMD Charter and Milestones

Linda,

Thanks for suggesting text. I have a few comments on this. The main comment
is that I do not think we are ready to create a working group that actually
develops the solutions. I would like to see the "document the scaling
characteristics" stage successfully completed first before chartering any
work on solutions. This is not to say that we can't do the work -- even in
the schedule you outline in the milestones -- but at least I personally have
some trouble committing to the solution part before I fully understand the
current characteristics.

(1）To document the scaling characteristics of ARP (IPv4) and ND (IPv6) with
respect to increasing numbers of hosts in data centers, (2) to identify
limitations of ARP and ND in such environments, (3) provide design
recommendations intended to minimize issues associated with the identified
limitations, and (4) to develop appropriate solutions to better support data
centers with large number of hosts.

=>

（1）To document the scaling characteristics of ARP (IPv4) and ND (IPv6)
with respect to increasing numbers of hosts in data centers and (2) provide
operational recommendations intended to minimize issues associated with the
limits inherent in these characteristics.

Jari