ZyXEL Communications ZyXEL Dimension ES-2024 - Manual (Page 57)

Dimension ES-2024 Ethernet Switch
Basic Setting 6-5
See the VLAN chapter for information on port-based and 802.1Q tagged VLANs.
6.5 IGMP Snooping
IGMP (Internet Group Multicast Protocol) is a session-layer protocol used to establish membership in a multicast
group - it is not used to carry user data. Refer to RFC 1112 and RFC 2236 for information on IGMP versions 1
and 2 respectively.
A layer-2 switch can passively snoop on IGMP Query, Report and Leave (IGMP version 2) 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.
Without IGMP snooping, multicast traffic is treated in the same manner as broadcast traffic, that is, it is forwarded
to all ports. With IGMP snooping, group multicast traffic is only forwarded to ports that are members of that
group. IGMP Snooping generates no additional network traffic, allowing you to significantly reduce multicast
traffic passing through your switch.
6.6 Switch Setup Screen
Click Basic Setting and then Switch Setup in the navigation panel display the screen as shown. The VLAN setup
screens change depending on whether you choose 802.1Q or Port Based in the VLAN Type field in this
screen. Refer to the chapter on VLANs.