Multicast; Chapter 23 Multicast; Multicast Overview; What You Can Do - ZyXEL Communications GS2210 Series User Manual

23.1 Multicast Overview

This chapter shows you how to configure various multicast features.
Traditionally, IP packets are transmitted in one of either two ways - Unicast (1 sender to 1 recipient)
or Broadcast (1 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 - it is not used to carry user data. Refer to RFC 1112, RFC 2236
and RFC 3376 for information on IGMP versions 1, 2 and 3 respectively.

23.1.1 What You Can Do

• Use the Multicast Setup screen
group multicast traffic only to ports that are members of that group.
• Use the IPv4 Multicast Status screen
information.
• Use the MVR screens
receiver port(s) and a source port for each multicast VLAN.

23.1.2 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/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 allows the Switch to learn multicast groups without you having to manually
configure them.
GS2210 Series User's Guide
C
HAPTER
(Section 23.2 on page
(Section 23.3 on page
(Section 23.5 on page 173) to create multicast VLANs and select the

Multicast

166) to enable IGMP snooping to forward
167) to view multicast group
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