Westermo MDI-112 Series, Руководство пользователя

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4.8 Multicast Filtering
For multicast filtering, the switch uses IGMP Snooping technology. IGMP
(Internet Group Management Protocol) is an Internet Protocol that provides a
way for internet device to report its multicast group membership to adjacent
routers. Multicasting allows one computer on the internet to send data to a
multitude of other computers that have identified themselves as being interested
in receiving the originating computers data.
Multicasting is useful for such applications as updating the address books of
mobile computer users in the field, sending out newsletters to a distribution list,
and broadcasting streaming media to an audience that has tuned into the event
by setting up multicast group membership.
In effect, IGMP Snooping manages multicast traffic by making use of switches,
routers, and hosts that support IGMP. Enabling IGMP Snooping allows the ports
to detect IGMP queries, report packets, and manage multicast traffic through the
switch. IGMP has three fundamental types of messages, as shown below:
Message Description
Query A message sent from the querier (an IGMP router or a switch) which
asks for a response from each host that belongs to the multicast
group.
Report A message sent by a host to the querier to indicate that the host
wants to be or is a member of a given group indicated in the report
message.
Leave Group A message sent by a host to the querier to indicate that the host has
quit as a member of a specific multicast group.
You can enable IGMP Snooping and IGMP Query functions here. You will see the
information of the IGMP Snooping function in this section, including different
multicast groups’ VID and member ports, and IP multicast addresses that range
from 224.0.0.0 to 239.255.255.255.
In this section, Force filtering can determined whether the switch flooding
unknown multicast traffic or not.
Following commands are included in this section:
4.8.1 IGMP Snooping
4.8.2 IGMP Query
4.8.3 Force Filtering
4.8.4 CLI Commands of the Multicast Filtering