Protocol Independent Multicast (PIM) – Sparse mode allows port(s) to hear broadcast while prunning out other port(s) that it does not need to hear multicasts from.
PIM-sparse requires: (1) Boot Strap Router (BSR) and (2) Rendezvous Point (RP)
BSR is elected from failover “candidate routers” to hold the multicast group to RP mappings.
Bootstrap messages are sent between candidate routers that contain RP information. RP is where senders and listeners connect to form multicast groups.
Router with the highest IP will win an election. To influence this process, one must set priorities (0 to 255 where 0 is the highest).
Cisco 6500 (IOS 12.2(18))
ip multicast routing //enable multicast routing
ip pim bsr-candidate vlan 5 //enable router to be Candidate BSR, part 1
ip pim rp-candidate vlan 5 //enable router to be Candidate BSR, part 2
interface vlan 5
ip pim sparse-mode //add PIM-SM to the router interface VLAN 5 (and any other VLAN)
Enterasys N3 (OS 6.12.08) with Advanced Router License
show system hardware //check that 256MB SDRAM is available for PIM
ip pim bsr-candidate vlan 5 //configure VLAN 5 as PIM candidate
ip pim rp-candidate 10.10.10.1 220.127.116.11 18.104.22.168 //Reverse of 21 bit mask for local interface ge.7.48
ip pim sparse-mode
sh ip pim neighbor //display PIM table
sh ip pim neighbor //same