Multicast Traffic is not flowing to a new Outgoing Interface
597
Created On 12/15/21 03:34 AM - Last Modified 10/22/25 03:12 AM
Symptom
- The Multicast traffic (10.0.0.1,239.1.1.1) is flowing correctly for an Outgoing Interface - OIF (E1/2)
show routing multicast route group 239.1.1.1 VIRTUAL ROUTER: default flags: L - source is local number of mfib entries shown: 2 group source flags incoming outgoing ----- ------ ----- -------- -------- 239.1.1.1 0.0.0.0 PIM Register tunnel ethernet1/2 ethernet1/1 239.1.1.1 10.0.0.1 ethernet1/1 ethernet1/2 PIM Register tunnel - A new Outgoing Interface (E1/3) is added, but no traffic is flowing to it
- IGMP shows the clients are requesting traffic
> show routing multicast igmp membership VIRTUAL ROUTER: default number of igmp entries shown: 6 interface group source up time expiry filter mode excl mode expiry v1 host timer v2 host timer last reporter --------- ----- ------ ------- ------ ----------- ---------------- ------------- ------------- ------------- /truncated/ ethernet1/3 239.1.1.1 0.0.0.0 510.35 27999 exclude 27999 0.00 252.09 192.168.3.90 /truncated/
- PIM table show the group (*,239.1.1.1) for the new OIF is in state "NoInfo"
> show routing multicast pim state VIRTUAL ROUTER: default (*, G): group RP up time upstream join st upstream join timer RPF interface RPF next hop ----- -- ------- ---------------- ------------------- ------------- ------------ /truncated/ 239.1.1.1. 192.168.0.1 2183.81 Joined 0.00 0 0.0.0.0 (*, G, I): group interface local membership join/prune st prune pending timer join expiry timer assert st assert timer assert winner addr assert winner metric ----- --------- ---------------- ------------- ------------------- ----------------- --------- ------------ ------------------ -------------------- 224.0.1.40 ethernet1/3 yes NoInfo 0.00 0.00 NoInfo 0.00 0.0.0.0 0 /truncated/ 239.1.1.1 ethernet1/2 no Join 0.00 188.46 NoInfo 0.00 0.0.0.0 0 239.1.1.1 ethernet1/3 yes NoInfo 0.00 0.00 NoInfo 0.00 0.0.0.0 0
Environment
- PAN-OS
- Multicast traffic
- PIM
Cause
The new OIF is not PIM DR interface
The PIM DR interface is in charge of performing the PIM related tasks.
Checking the PIM Interface status allows to confirm that there is another DR.
> show routing multicast pim interface VIRTUAL ROUTER: default interface address DR hello interval join/prune interval assert interval dr priority bsr border --------- ------- -- -------------- ------------------- --------------- ----------- ---------- /truncated/ ethernet1/3 192.168.3.1 192.168.3.10 30 60 177 1 no /truncated/
Resolution
Review the design of the network segment.
If the (S,G) traffic needs to go through the new interface, the interface needs to be elected PIM DR.
To do so:
- Increase the PIM DR priority
- Make sure the interface has the highest IP address in the LAN.
Note: In case of priority tie, the interface with the highest IP address is elected PIM DR.
Additional Information
Admin Guide - Configure IP Multicast
The PIM DR state is not preemptive: the elected PIM DR remains DR as long it is up.