Symptoms
Using PIM-Sparse Mode for multicast traffic with BGP for unicast routing/reverse path filtering may prevent PIM neighbor routers from switching from the RPT to the SPT.
Impact
Routers upstream and including BIG-IP will never receive PIM JOIN messages from the rendezvous point, which is required for traffic to switch from the RPT to the SPT.
The sender's DR may continue to send traffic to the RP in register messages indefinitely.
Conditions
-- PIM-Sparse Mode.
-- BGP.
-- Floating self IP address.
Workaround
Remove the floating self IP address from the traffic group or select a routing protocol that does not use it, such as OSPF.
Fix Information
PIM can now send hello messages from a floating self IP address.
Behavior Change
PIM can now send hello messages using a floating self IP address. Configure it in imish under the interface along with the PIM mode:
#imish
imish> enable
imish# configure terminal
imish(config)# interface external
imish(config-if)# ip pim use-floating-address
Upon failover, the previously active unit will send hellos from a non-floating self IP address, and the new active unit will begin sending hellos from the floating self IP address.
No state is shared between the units; both will generate a new PIM generation ID, and the state of all multicast routes will be reset and need to reconverge.
