Multicast traffic not passing through a VAP group to a PIM sparse-mode neighbor on X-Series

Products

• XOS

Issue/Introduction

Multicast packets fail to pass through when the next hop route uses a VIP IP in the following configuration:

Rendez-vous point IP config:
ip pim rp-address 172.30.16.222 

Default route config in XOS for the affected VAP group:
ip route 0.0.0.0/0 172.31.67.10 vap-group <VAPname> circuit <circuit name>

PIM debug showing a similar output:
PIM-SM: MRIB.next_hop_rp(172.30.16.222): nexthop 172.31.67.10 
PIM-SM: US (*,G): No RPF neighbor for (*, 225.1.1.2) 

Cause

The default gateway address 172.31.67.10 is likely not a direct PIM neighbor, but a virtual IP address (VRRP/HSRP/GLBP). 

The PIM neighbors must use a physical interface IP, not a virtual IP address.

Resolution

Have a more specific route(s) to the rendez-vous point IP address than a default route.
In this case, you may need to add multiple static routes to ensure redundancy for unicast traffic.

# configure ip route 172.30.16.222/32 <nexthop1> vap-group <VAPname>  
# configure ip route 172.30.16.222/32 <nexthop2> vap-group <VAPname>  

 

Workaround

N/A