802.3ah OAM Information (`efm_oam_information`)

Layer: L2 (data link)
Header: variable length
Notes: PTP / ESMC / CFM / R-APS / 802.3ah OAM (P2)

Reached from

Lower layer	Selector	Value
`ethernet2`	First 8 bits of the payload when `ethertype` = 34825 (0x8809)	3 (0x03)
`efm_oam`	`code`	0 (0x00) (re-decodes this layer)

Fields

Field	Type	Default	Auto	Description
`subtype`	`uint(8)`	`3`		Slow Protocols subtype (3 = OAM).
`flags`	`flags(16)`	`0x50`		Flags: link fault, dying gasp, critical event, local / remote evaluating and stable.
`code`	`enum(8)`	`0` (information)		OAMPDU code: 0x00 Information, 0x01 Event Notification, 0x02 Variable Request, 0x03 Variable Response, 0x04 Loopback Control, 0xfe Organization Specific.
`tlvs`	`tlv` — up to and including the first item of type 0, or the end of the PDU	2 items		Information TLVs (8-bit type, 8-bit length including the header, Auto): Local / Remote Information, Organization Specific, closed by the End TLV (type 0).

`flags`

Bit	Mask	Name
0	1 (0x0001)	`link_fault`
1	2 (0x0002)	`dying_gasp`
2	4 (0x0004)	`critical_event`
3	8 (0x0008)	`local_evaluating`
4	16 (0x0010)	`local_stable`
5	32 (0x0020)	`remote_evaluating`
6	64 (0x0040)	`remote_stable`

`code`

Value	Name
0 (0x00)	`information`
1 (0x01)	`event_notification`
2 (0x02)	`variable_request`
3 (0x03)	`variable_response`
4 (0x04)	`loopback_control`
254 (0xfe)	`organization_specific`

`tlvs`

Type 8 bits, length 8 bits.
The length counts the type and length fields too.
Unknown types are kept as raw value octets.

Type	Name	Value fields	Description
0 (0x00)	`end`	(type only, no length or value)
1 (0x01)	`local_information`	`oam_version`, `revision`, `state_reserved`, `multiplexer_action`, `parser_action`, `oam_configuration`, `oampdu_configuration_reserved`, `max_oampdu_size`, `oui`, `vendor_specific_information`
2 (0x02)	`remote_information`	`oam_version`, `revision`, `state_reserved`, `multiplexer_action`, `parser_action`, `oam_configuration`, `oampdu_configuration_reserved`, `max_oampdu_size`, `oui`, `vendor_specific_information`
254 (0xfe)	`organization_specific`	`oui`, `value`

`tlvs` › `local_information`

Field	Type	Default	Auto	Description
`oam_version`	`uint(8)`	`1`
`revision`	`uint(16)`	`0`
`state_reserved`	`uint(5)`	`0`
`multiplexer_action`	`enum(1)`	`0` (forward)
`parser_action`	`enum(2)`	`0` (forward)
`oam_configuration`	`flags(8)`	`0x9`
`oampdu_configuration_reserved`	`uint(5)`	`0`
`max_oampdu_size`	`uint(11)`	`1518`
`oui`	`uint(24)`	`0`
`vendor_specific_information`	`uint(32)`	`0`

`tlvs` › `local_information` › `multiplexer_action`

Value	Name
0	`forward`
1	`discard`

`tlvs` › `local_information` › `parser_action`

Value	Name
0	`forward`
1	`loopback`
2	`discard`

`tlvs` › `local_information` › `oam_configuration`

Bit	Mask	Name
0	1 (0x01)	`active_mode`
1	2 (0x02)	`unidirectional`
2	4 (0x04)	`remote_loopback`
3	8 (0x08)	`link_events`
4	16 (0x10)	`variable_retrieval`

`tlvs` › `remote_information`

Field	Type	Default	Auto	Description
`oam_version`	`uint(8)`	`1`
`revision`	`uint(16)`	`0`
`state_reserved`	`uint(5)`	`0`
`multiplexer_action`	`enum(1)`	`0` (forward)
`parser_action`	`enum(2)`	`0` (forward)
`oam_configuration`	`flags(8)`	`0x9`
`oampdu_configuration_reserved`	`uint(5)`	`0`
`max_oampdu_size`	`uint(11)`	`1518`
`oui`	`uint(24)`	`0`
`vendor_specific_information`	`uint(32)`	`0`

`tlvs` › `remote_information` › `multiplexer_action`

Value	Name
0	`forward`
1	`discard`

`tlvs` › `remote_information` › `parser_action`

Value	Name
0	`forward`
1	`loopback`
2	`discard`

`tlvs` › `remote_information` › `oam_configuration`

Bit	Mask	Name
0	1 (0x01)	`active_mode`
1	2 (0x02)	`unidirectional`
2	4 (0x04)	`remote_loopback`
3	8 (0x08)	`link_events`
4	16 (0x10)	`variable_retrieval`

`tlvs` › `organization_specific`

Field	Type	Default	Auto	Description
`oui`	`uint(24)`
`value`	`bytes` — rest of the PDU

Sample templates

efm-oam-information — templates/protocols/oam/efm-oam-information.wpg.yaml