Subject: [armd] new draft posted to manage ARP broadcasts in data center

From: "Shah, Himanshu" <[email-masked]>
Date: Mon, 25 Oct 2010 21:36:54 -0400

Hello All -

We have posted the following draft. 

Comments welcome.

Thanks,

Himanshu

Filename:      draft-shah-armd-arp-reduction

Version:       01

Staging URL:

http://www.ietf.org/staging/draft-shah-armd-arp-reduction-01.txt

Title:               ARP Broadcast Reduction for Large Data Centers

Creation_date:       2010-10-25

WG ID:               Individual Submission

Number_of_pages: 10

Abstract:

With the emergence server virtualization technologies, a host is able to
support multiple Virtual Machines (VMs) in a single physical machine.
Data centers can leverage these capabilities to instantiate on the order
of 10s to 100s of VMs in a server. Each VM operates as an independent IP
host with a set of Virtual Network Interface Cards (vNICs), each having
its own MAC address and mapping to a physical Ethernet interface. These
physical servers are typically installed in a rack with their Ethernet
interfaces connected to a top-of-rack

(ToR) switch. The ToR switches are interconnected through End-of-
the-Row (EoR) or aggregation switches which are in turn connected to
core switches.  

As discussed in [ARP-Problem] the host VMs use ARP broadcasts to find
other host VMs and use periodic (broadcast) Gratuitous ARPs to refresh
their IP to MAC address binding in other VM hosts. Such broadcasts in a
large data center with potentially thousands of VM hosts in a Layer 2
based topology can overwhelm the network. 

This memo proposes mechanisms to reduce the number of broadcasts that
are sent throughout the network. This is done by having the ToR switches
intelligently process ARP packets, rather than simply broadcasting them
throughout the broadcast domain.  

While this document specifically addresses ARP, the Neighbor Discovery
mechanisms used by IPv6 hosts that make use of multicast rather than
broadcast also pose similar issues for the data center. 

The solutions defined herein should be equally applicable to hosts
running IPv6.  The details will be specified in a subsequent revision. 

Submitter: Himanshu Shah ([email-masked])

Author(s):

Himanshu shah, [email-masked]

Anoop Ghanwani, [email-masked]