ZyXEL Communications manual Igmp Snooping, MSAP2000 Aams User’s Guide General Setup

MSAP2000 AAMS User’s Guide

Table 10 General Setup (continued)

LABEL	DESCRIPTION
New Time	Enter the new time in hour, minute and second format. The new time then
(hh:min:ss)	appears in the Current Time field after you click Apply.
Current Date	This field displays the date you open this menu.
New Date (yyyy-	Enter the new date in year, month and day format. The new date then appears
mm-dd)	in the Current Date field after you click Apply.
Time Zone	Select the time difference between UTC (Universal Time Coordinated, formerly
	known as GMT, Greenwich Mean Time) and your time zone from the drop-
	down list box.
Apply	Click Apply to save your changes to the MSAP2000 AAMS’s volatile memory.
	The MSAP2000 AAMS loses these changes if it is turned off or loses power, so
	use the Config Save link on the navigation panel to save your changes to the
	non-volatile memory when you are done configuring.
Cancel	Click Cancel to start configuring the screen again.

6.4 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 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. IGMP snooping allows the switch to learn multicast groups without you having to manually configure them.

The switch forwards multicast traffic destined for multicast groups (that it has learned from IGMP snooping or that you have manually configured) to ports that are members of that group. The switch discards multicast traffic destined for multicast groups that it does not know. IGMP snooping generates no additional network traffic, allowing you to significantly reduce multicast traffic passing through your switch.

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