Atlantis A02-PL303-WN - Manual (Page 38)

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WI-FI MUltimedia
DESCRIPTION MEANING
WMM This feature is used to control the prioritization of traffic
according to 4 Access categories: Voice, Video, Best Effort and
Background. Default is Enable.
APSP Automatic Power Save Delivery (APSD) is an efficient power
management mechanism and is very useful for a VoIP phone.
You can select enable or disable this feature.
Default is Disable.
IGMP Snooping
DESCRIPTION MEANING
IGMP Snooping
Service
Allows a layer 2 switch to manage the transmission of any
incoming IGMP multicast packet groups between the host and
the router. Default is set to enable.
Traditionally, IP packets are transmitted in one of either two ways - Unicast (1
sender - 1 recipient) or Broadcast (1 sender - everybody on the network). Multicast
delivers IP packets to a group of hosts on the network - not everybody and not just
1.
IGMP (Internet Group Multicast Protocol) is a network-layer protocol used to
establish membership in a Multicast group - it is not used to carry user data. IGMP
version 2 (RFC 2236) is an improvement over version 1 (RFC 1112) but IGMP
version 1 is still in wide use. If you would like to read more detailed information
about interoperability between IGMP version 2 and version 1, please see sections 4
and 5 of RFC 2236. The class D IP address is used to identify host groups and can
be in the range 224.0.0.0 to 239.255.255.255. The address 224.0.0.0 is not
assigned to any group and is used by IP multicast computers. The address
224.0.0.1 is used for query messages and is assigned to the permanent group of all
IP hosts (including gateways). All hosts must join the 224.0.0.1 group in order to
participate in IGMP. The address 224.0.0.2 is assigned to the multicast routers
group.
The NetPower 303 WN supports both IGMP version 1 (IGMP-v1) and IGMP version
2 (IGMP-v2). At start up, the device queries all directly connected networks to
gather group membership. After that, the device periodically updates this
information.