Cisco Wireless LAN Controller Multicast Enabled

Enabled Multicast Mode on the Cisco Wireless LAN Controllers, but still could not hear multi casted MoH.  Turns out that the management interface's default router and dynamic interfaces' default router interfaces need to have "ip pim spare-mode".

MoH multicast from remote site SRST router

Setup Cisco IP phones at a remote site to get the MoH from a file on the WAN router at the site.  It turns out have to use spare-dense or dense mode for it to work on the interfaces between LAN and WAN router.

Multicast Audio 6 seconds delay

Have been trying to setup Cisco CallManager Music on Hold (MOH) to do multicasting on the network.  Had issue with the music takes about 6 seconds to be heard.  It doesn't matter, whether used spare or dense mode on the network.  It turns out a Cisco bug CSCth66667 might have caused it.  After upgrade network core switch (Catalyst 6513) where RP is at to 12.2(33)SXI5, the issue was gone.