Multicast; Chapter 21 Multicast; Multicast Overview; What You Can Do - ZyXEL Communications GS1915 Series User Manual

21.1 Multicast Overview

This chapter shows you how to configure various multicast features.
Traditionally, IP packets are transmitted in one of either two ways
or Broadcast (one sender to everybody on the network). Multicast delivers IP packets to just a group of
hosts on the network.
IGMP (Internet Group Management Protocol) is a network-layer protocol used to establish membership
in a multicast group
information on IGMP versions 1, 2 and 3 respectively.

21.1.1 What You Can Do

• Use the Multicast Setup screen
screens where you can configure IPv4 multicast settings.
• Use the IPv4 Multicast Status screen
information.
• Use the IGMP Snooping screen
group multicast traffic only to ports that are members of that group.
• Use the IGMP Snooping VLAN screen
VLANs.

21.1.2 What You Need to Know

Read on for concepts on Multicasting that can help you configure the screens in this chapter.
IP Multicast Addresses
In IPv4, a multicast address allows a device to send packets to a specific group of hosts (multicast
group) in a different subnetwork. A multicast IP address represents a traffic receiving group, not
individual receiving devices. IP addresses in the Class D range (224.0.0.0 to 239.255.255.255) are used for
IP multicasting. Certain IP multicast numbers are reserved by IANA for special purposes (see the IANA
website for more information).
IGMP Snooping
A Switch can passively snoop on IGMP packets transferred between IP multicast routers or switches and
IP multicast hosts to learn the IP multicast group membership. It checks IGMP packets passing through it,
picks out the group registration information, and configures multicasting accordingly. IGMP snooping

Chapter 21 Multicast

it is not used to carry user data. Refer to RFC 1112, RFC 2236 and RFC 3376 for
–
(Section 21.2 on page
(Section 21.3 on page
(Section 21.3.1 on page
(Section 21.3.2 on page
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C
H A P T E R

Multicast

Unicast (one sender to one recipient)
–
168) to display the links to the configuration
168) to view IPv4 multicast group
169) to enable IGMP snooping to forward
171) to perform IGMP snooping on
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