
When you enable IGMP snooping, you might suspect that the switch will only look at IGMP packets. This is not the case though. There might be differences between vendors/models.

For example, on Cisco IOS it will look at the following packets:

- IGMP General Query (0100.5e00.0001)
- OSPF (0100.5e00.0005 and 0100.5e00.0006)
- PIM version 1 and HSRP (0100.5e00.0006)
- PIM version 2 (0100.5e00.000d)
- DVMRP (0100.5e00.0004)

Most switches will check for PIM hello packets. This is true for Cisco Nexus (3600) switches, Huawei,  and Cisco HPE switches. 

When you enable [Multicast - PIM Snooping](/multicast-pim-snooping) they will check additional PIM packets.



IGMP snooping inspects PIM hello packets

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