Cisco Support Community
Community Member

N7K Null OIF list

In a lab environment, customer has a 7000 running 6.03a, with core and distribution VDCs, interconnected at L3.  Access 6509 is connec ted to the dist VDC at L2.  A multicast source is connected to the 6509, and a receiver is connected to the core vdc.  The receiver joins groups, and the source transmits in these same groups.  Under anycast rp and auto-rp, all RP information is correct on both VDCs, as is RPF information.  Mroutes show (S,G) entries back to the source on the dist VDC (which is the RP), and (*,G) entries on the core VDC, with correct RPF pointer back to the RP.  IGMP shows joins on both VDCs.  The problem is that the core VDC has null OIF lists for the (*,G) entries.  No traffic is seen at the receiver, and no crossover to SPT occurs.  Pings between all test components succeed.

Any ideas as to why the Nexus will not populate an OIF when it sees joins coming in?  There are no PIM neighbors on the receiver's VLAN.

I should note that we did see correct behavior when we connected a second dist VDC, also configured as an RP, with source on one dist vdc, and receiver on the other.  The full environment would consist of a pair of dist VDCs with a pair of access 6509s interconnected at L2, and VPC between the dist VDCs.  The dist VDCs would be connected to the core VDCs with a full mesh of L3 links.  We disabled some VPC and L3 links to force the data path.  All unicast and PIM routing was correct, running over the enabled links. 

In all tests, the source and receiver were in different vlans, so PIM would always be involved in forwarding the packets.

BGP is the unicast protocol, and is working correctly.

Thanks for any insights

Everyone's tags (3)
CreatePlease to create content