Check this link out
http://www.cisco.com/en/US/products/sw/iosswrel/ps1835/products_configuration_guide_chapter09186a00800ca794.html
The basic tasks in the first two sections are required; the tasks in the remaining sections are optional.
• Enabling IP Multicast Routing (Required)
• Enabling PIM on an Interface (Required)
• Configuring Auto-RP (Optional)
• IGMP Features Configuration Task List (Optional)
• Configuring the TTL Threshold (Optional)
• Disabling Fast Switching of IP Multicast (Optional)
• SAP Listener Support Configuration Task List (Optional)
• Enabling the Functional Address for IP Multicast over Token Ring LANs (Optional)
• Configuring PIM Version 2 (Optional)
