Product and Software: This article applies to all Aruba controllers that run ArubaOS 3.4 or later.
Without any special tuning, multicast packets are sent at either basic rate or support rate, whichever is lower. For example, if you have the following rates:
802.11a Basic Rates 18 24 802.11a Transmit Rates 6 9 12 18 24 36 48 54Multicast/broadcast packets are sent at 6 Mb/s (when the 5 GHz channel is used) because it is the lowest of all rates. This applies to 'N' as well.
BC/MC Rate Optimization
When this feature is enabled, the control rate is used instead of the lowest of the basic rate and transmit rate. The multicast traffic rate could go up to 24 Mb/s. Note that the multicast traffic is still sent to the multicast MAC address.
For more information on these three rates, refer to KB Answer ID 435.
Dynamic Multicast Optimization
The controller keeps a record of the stations in each multicast group, converts the multicast MAC to unicast MAC (destination IP address remains as multicast), and sends to that station at the unicast rate.
To enable it:
(controller) (Virtual AP profile "default") #dynamic-mcast-optimization?
dynamic-mcast-optimiz.. Enable/Disable dynamic multicast optimization (DMO)feature.dynamic-mcast-optimiz.. Maximum number of HT STAs in a multicast groupbeyond which dynamic multicast optimization stops.Allowed range [2-255](controller) (Virtual AP profile "default") #dynamic-mcast-optimization ?<cr>(controller) (Virtual AP profile "default") #dynamic-mcast-optimization-thresh ?<dynamic-mcast-optimi.. Maximum number of HT STAs in a multicast groupbeyond which dynamic multicast optimization stops.Allowed range [2-255]
(controller) #show wlan virtual-ap default
Virtual AP profile "default"----------------------------Parameter Value--------- -----Virtual AP enable EnabledAllowed band allAAA Profile default802.11K Profile defaultSSID Profile defaultVLAN N/AForward mode tunnelDeny time range N/AMobile IP EnabledHA Discovery on-association DisabledDoS Prevention DisabledStation Blacklisting EnabledBlacklist Time 3600 secDynamic Multicast Optimization (DMO) Disabled <<<<<<<<<Dynamic Multicast Optimization (DMO) Threshold 6 <<<<<<<<<Authentication Failure Blacklist Time 3600 secMulti Association DisabledStrict Compliance DisabledVLAN Mobility DisabledRemote-AP Operation standardDrop Broadcast and Multicast DisabledConvert Broadcast ARP requests to unicast DisabledBand Steering DisabledWMM Traffic Management Profile N/A
Works on all APs (legacy or 11n), however, only works on newer platform (M3 or 3000 series controllers).
· Needs to enable IGMP proxy.
· IGMP query always optimized and send to each station by the controller.
· DMO threshold is per virtual AP profile and per AP, not per radio. For example, consider a dual-radio AP that has the DMO threshold configured as 6 and there are six users on the 5 GHz band. When the seventh user joins, regardless of the RF band, the DMO falls back to the traditional behavior. No multicast to unicast conversion occurs. Multicast is sent as multicast into the air.
This is important if VLAN pooling is configured. In that case, a higher DMO threshold is desired. The number depends on the combination of several factors such as the size of the VLAN pool, the number of receivers, and the density of the receivers.
When you optimize multicast traffic, DO NOT enable "broadcast-filter all" in the virtual AP profile. This feature is designed to reduce excessive multicast and broadcast traffic when the customer has a flat LAN (for example, a /16 IP subnet). When this feature is enabled, the controller drops all broadcast and multicast traffic except for DHCP.
For more details on "broadcast-filter" usage.
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