PIM (`pim`)

Layer: L3 (network)
Header: 4 octets (fixed)
Notes: Multicast control protocols

Reached from

Lower layer	Selector	Value
`ipv4`	`protocol`	103 (0x67)

Field	Type	Default	Auto	Description
`version`	`uint(4)`	`2`		PIM version (2).
`type`	`enum(4)`	`0` (hello)	Protocol number of the next layer (see Next layer)	PIM message type (Auto from the body: 0 Hello, 1 Register, 3 Join/Prune).
`reserved`	`uint(8)`	`0`
`checksum`	`uint(16)`		Internet checksum over the header and everything after it	Internet checksum (whole message; Register: first 8 octets only) (Auto).

The next layer is selected by type; when the field is Auto the builder writes the value of the protocol stacked above.

Value	Protocol	Note
0	`pim_hello`
3	`pim_join_prune`

Level	Rule
warning	`version` = 2