User Guide

OmniAccess SafeGuard OS Administration Guide
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Chapter 5: Setting Up SafeGuard Switches
Requests Relayed............................... 0
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IP Multicast Routing
IP multicasting allows a device on a LAN or VLAN to send packets, not to just one
recipient, but to a group or collection of other devices. Multicasting is considered a more
efficient method of routing because it conserves bandwidth and reduces traffic by being
able to deliver simultaneously a single stream of information to multiple devices.
In a multicast environment, instead of using an individual IP address, the source device
uses an address that identifies the members of the group. When the source device sends
the group IP address, routers on the LAN or VLAN forward the packets to all the
members of the multicast group. If necessary, the routers forward duplicate data packets
wherever the path to recipients diverge.
Internet Group Management Protocol (IGMP) is a multicast group membership
discovery protocol. In subnets where IGMP is configured, a host that wants to be a data
receiver joins the group by sending a message to a multicast router on a local interface.
There are three versions of IGMP: IGMPv1, IGMPv2, and IGMPv3. All three versions are
supported by SafeGuard OS. For more details, see Configuring IGMP Snooping on page 164.