Cisco 8861 - Page 58

Cisco IP Phone 8861 and 8865 Wireless LAN Deployment Guide
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If utilizing multicast, then Enable Global Multicast Mode and Enable IGMP Snooping should be enabled.
If utilizing layer 3 mobility, then Symmetric Mobility Tunneling should be Enabled.
In the recent versions, Symmetric Mobility Tunneling is enabled by default and non-configurable.