Troubleshooting 0 bit traffic
I just ran into an issue where I could see the multicast join was happening and the mroute seemed to be formed on my Nexus 7K, but we were receiving 0 bits of traffic. This was a turn up for a new system so we started troubleshooting everything and anything. Looking at the the show ip mroute detail command I saw the below information.
(x.x.x.x/32, 232.125.21.98/32), uptime: 01:35:26, igmp(1) pim(0) ip(0)
Stats: 0/0 [Packets/Bytes], 0.000 bps
Incoming interface: Vlan4, RPF nbr: x.x.x.x
Outgoing interface list: (count: 1)
Vlan1951, uptime: 01:35:26, igmp
In the above the first thing that stood out was that it had a 0 bit rate. Next I looked at the incoming and outgoing interface information. I took a look at my incoming interface and saw the below configuration.
interface Vlan4
no shutdown
vrf member mux
ip address x.x.x.x/31
ip ospf network point-to-point
ip router ospf 3 area 0.0.0.0
This lead to the immediate Eureka moment I was looking for. The engineer that built the Vlan forgot to actually allow multicast traffic! I added the typical multicast configuration to the Vlan and the multicast traffic began to flow.
interface Vlan4
no shutdown
vrf member mux
ip address 100.114.4.225/31
ip ospf network point-to-point
ip router ospf 3 area 0.0.0.0
ip pim sparse-mode
ip igmp version 3
After waiting a little bit the traffic multicast traffic on the VLAN began to flow and we could see statistics.
(x.x.x.x/32, 232.125.21.58/32), uptime: 03:30:19, pim(0) ip(0) igmp(1)
Stats: 4334868/5895420480 [Packets/Bytes], 75.250 mbps
Incoming interface: Vlan4, RPF nbr: x.x.x.x
Outgoing interface list: (count: 1)
Vlan1951, uptime: 02:32:37, igmp
Overall this was a simple multicast troubleshooting issue, but if you don’t know what your looking for it can definitely become difficult.