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4.8 Multicast
4.8.1 IGMP Snooping
The
Internet Group Management Protocol (IGMP)
lets host and routers 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 the Internet Group Management Protocol (IGMP) Snooping
Computers and network devices that want to receive multicast transmissions need to inform nearby routers that they will become
members of a multicast group. The
Internet Group Management Protocol (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IGMP is also used to periodically check the multicast group for members that are no longer active.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 the ‘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 if multicast
packets should be forwarded to a given sub network or not. The router can check, using IGMP, to see if there is at least one
member of a multicast group on a given subnet work. If there are no members on a sub network, packets will not be forwarded to
that sub network.
Figure 4-8-1:
Multicast Service
Summary of Contents for NS4750-24S-4T-4X
Page 1: ...NS4750 24S 4T 4X User Manual P N 1702826 REV 00 01 ISS 14JUL14 ...
Page 56: ...56 Figure 4 2 7 Privilege Levels Configuration Page Screenshot ...
Page 110: ...110 Figure 4 4 6 Mirror Configuration Page Screenshot ...
Page 117: ...117 Figure 4 5 4 LACP Port Configuration Page Screenshot ...
Page 174: ...174 Figure 4 7 10 MST1 MSTI Port Configuration Page Screenshot ...
Page 180: ...180 Figure 4 8 2 Multicast Flooding ...
Page 249: ...249 Figure 4 9 18 Voice VLAN Configuration Page Screenshot ...
Page 271: ...271 Counter Counts the number of frames that match this ACE ...
Page 281: ...281 Figure 4 11 4 Network Access Server Configuration Page Screenshot ...
Page 315: ...315 ...
Page 328: ...328 ...
Page 335: ...335 ...
Page 346: ...346 Figure 4 14 1 LLDP Configuration Page Screenshot ...
Page 350: ...350 Figure 4 14 2 LLDP MED Configuration Page Screenshot ...
Page 372: ...372 Figure 4 16 1 Loop Protection Configuration Page Screenshot ...