Chapter 24 Multicast
24.1.3 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.
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. IGMP snooping generates no additional network traffic, allowing you to significantly reduce multicast traffic passing through your Switch.
24.1.4 IGMP Snooping and VLANs
The Switch can perform IGMP snooping on up to 16 VLANs. You can configure the Switch to automatically learn multicast group membership of any VLANs. The Switch then performs IGMP snooping on the first 16 VLANs that send IGMP packets. This is referred to as auto mode. Alternatively, you can specify the VLANs that IGMP snooping should be performed on. This is referred to as fixed mode. In fixed mode the Switch does not learn multicast group membership of any VLANs other than those explicitly added as an IGMP snooping VLAN.
24.2 Multicast Status
Click Advanced Applications > Multicast to display the screen as shown. This screen shows the multicast group information. See Section 24.1 on page 205 for more information on multicasting.
Figure 105 Advanced Application > Multicast
The following table describes the labels in this screen.
Table 59 Advanced Application > Multicast Status
LABEL | DESCRIPTION |
Index | This is the index number of the entry. |
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VID | This field displays the multicast VLAN ID. |
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Port | This field displays the port number that belongs to the multicast group. |
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Multicast Group | This field displays IP multicast group addresses. |
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