Technical Note
Copyright © 2008 VMware, Inc. All rights reserved.
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Using IP Multicast with VMware® ESX 3.5
VMware ESX 3.5
IP multicast is a popular protocol implemented in many applications for simultaneously and efficiently
delivering information to multiple destinations. Multicast sources send single copies of information over the
network and let the network take responsibility for replicating and forwarding the information to multiple
recipients.
IP multicast is one of three commonly used methods of forwarding packets on an IP network. These methods
are:
Unicast—One‐to‐one packet delivery from a source to a single destination. This is the most common and
familiar form of traffic, with the destination IP address representing a single unique destination.
Broadcast—Packet delivery to all nodes within an IP network. The destination address for an IP broadcast
is all binary ones in the host portion of the destination IP address.
Multicast—Packet delivery to a group of destinations denoted by a multicast IP address. Membership of
this group is coordinated through the Internet Group Management Protocol (IGMP).
A fourth method, called anycast, is rarely used.
This paper provides an overview of IP multicast and support for this protocol in VMware ESX 3.5. It covers
the following topics:
“IP Multicast Address Space” on page 1
“Layer 2 Multicast Addressing” on page 2
“IP Multicast Groups” on page 2
“IGMP Versions” on page 2
“Operation of Multicast on a Physical Network” on page 3
“Operation of Multicast on an ESX Virtual Switch” on page 3
“Considerations for VMotion” on page 4
“NIC Teaming Considerations” on page 6
“IP Multicast Parameters on ESX” on page 7
“Physical Switch and Router Considerations” on page 8
IP Multicast Address Space
IP multicast destinations are represented by a group IP address from the old Class D IP address space between
224.0.0.0 and 239.255.255.255. Each individual address specifies a multicast group.
The IP multicast address space is broken into three