Luxul XMS-1024P - Manual (Page 119)

119
User Guide
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The Multicast module is used for Multicast Management configuration of the Switch
and includes four submenus:
IGMP Snooping, Multicast IP, Multicast Filter and
Packet Statistics.
8.1 IGMP Snooping
IGMP Snooping Process
A Switch running IGMP Snooping listens to the IGMP messages transmitted between
the client device and the Multicast Sever, tracking the IGMP messages and the regis-
tered Port(s). When the Switch receives an IGMP report message the Switch adds the
Port to the Multicast MAC Table. The Switch listens to IGMP leave message from the
client device, the router sends a Group-Specific Query message to the Port to check if
other client devices connected need the Multicast. If they do the Switch forwards the
report message to the Multicast Server. If they do not the Multicast Server will receive
no response from the hosts and the Switch will remove the Port from the Multicast
MAC Table. The Multicast Server regularly sends IGMP Query messages. After receiving
the IGMP Query message, the Switch will remove the Port from the Multicast MAC
Table if the Switch receives no IGMP report messages from the host within the
timeout period.
IGMP Messages
A Switch running IGMP Snooping processes the IGMP messages of different types
as follows.
1. IGMP Query Message
Query Messages sent by the Multicast Server fall into two categories; IGMP General
Query Message and IGMP Group-Specific-Query Message. The Multicast Server
regularly sends IGMP General Message to query if the Multicast group contains any
members. When receiving an IGMP Leave Message the receiving Port of the Multicast
Server will send an IGMP Group-Specific-Query Message to the Multicast group and
the Switch will forward IGMP Group-Specific-Query Message to check if other mem-
bers in the Multicast group connected to the Port need this Multicast.
When receiving IGMP General Query Messages, the Switch will forward them to all
member Ports of the VLAN hosting the Multicast. The Receiving Port will be processed
if the receiving Port is not a Multicast Server Port yet, it will be added to the Multicast
Server Port list with its Multicast Server Port time specified. If the receiving Port is
already a Multicast Server Port, its Multicast Server Port time will be reset.
When receiving IGMP Group-Specific-Query messages, the Switch will send the Group-
Specific Query Message to the members of the Multicast group being queried.
2. IGMP Report Message