Interlogix NS3562-8P-2S, Руководство пользователя, Страница: 115 / 245

Chapter 4: Web configuration
NS3562-8P-2S User Manual 113
The page includes the following fields:
Object Description
Unknown Multicast Action Unknown multicast traffic method:
Drop , Flood or send to Router Port .
IPv4 Forward Method Configure the IPv4 multicast forward method.
IPv6 Forward Method Configure the IPv6 multicast forward method.
Buttons
• Click Apply to apply changes.
IGMP snooping
The Internet Group Management Protocol (IGMP) allows hosts and routers to share
information about multicast groups memberships. IGMP snooping is a switch feature
that monitors the exchange of IGMP messages and copies them to the CPU for feature
processing. The overall purpose of IGMP snooping is to limit the forwarding of multicast
frames to only ports that are a member of the multicast group.
About IGMP snooping
Computers and network devices that need to receive multicast transmissions must
inform nearby routers that they will become members of a multicast group. IGMP is
used to communicate this information. IGMP is also used to periodically check the
multicast group for members that are no longer active. In the case where there is more
than one multicast router on a sub network, one router is elected as ‘queried.’ This
router then keeps track of the membership of the multicast groups that have active
members. The information received from IGMP is then used to determine whether or
not multicast packets should be forwarded to a given sub network. Using IGMP, the
router can check to see if there is at least one member of a multicast group on a given
sub network. If there are no members on a sub network, packets will not be forwarded
to that sub network.