Subject: I-D ACTION:draft-shah-armd-arp-reduction-00.txt

From: [email-masked]
Date: Mon, 18 Oct 2010 14:45:01 -0700 (PDT)

A New Internet-Draft is available from the on-line Internet-Drafts 
directories.

	Title		: ARP Reduction in Data Center
	Author(s)	: H. Shah
	Filename	: draft-shah-armd-arp-reduction-00.txt
	Pages		: 9
	Date		: 2010-10-18
	
With advent of virtual machine (VM) technologies, a host is able to 
   support multiple VMs in a single physical machine. The data center 
   application leverages these capabilities to instantiate upwards of 
   10s to 100s of VMs in a server. Each VM operates as an independent 
   IP host with its own MAC address associated with a virtual Network 
   Interface Card (vNIC) that maps to a single physical Ethernet 
   interface. These physical servers are typically stacked in a rack 
   with its Ethernet interface connected to top-of-the-rack (ToR) 
   switch. The ToR switches are interconnected through End-of-the-Row 
   (EoR) switch which in turn is connected to core switches.  
    
   As discussed in [ARP-Problem] the VM hosts use ARP broadcasts to 
   find other VM hosts 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 cause havoc.  
    
   This document describes a solution whereby a ToR switch assumes the 
   handling of the ARP broadcasts based on the ARP table that it 
   maintains by gleaning information from the passing ARP PDUs. When 
   the information is not new, gratuitous ARP PDUs are dropped and ARP 
   broadcast requests from hosts are responded by the switch from the 
   learned ARP information instead of forwarding them out. 

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