HSRPv1 (`hsrp`)

Layer: Application and control
Header: 20 octets (fixed)
Notes: Redundancy protocols (FHRP)

Reached from

Lower layer	Selector	Value
`udp`	`dst_port` / `src_port`	1985 (0x07c1)

Fields

Field	Type	Default	Auto	Description
`version`	`uint(8)`	`0`		HSRP version (0 for HSRPv1).
`op_code`	`enum(8)`	`0` (hello)		HSRP operation (0 = Hello, 1 = Coup, 2 = Resign, 3 = Advertise).
`state`	`enum(8)`	`16` (active)		Sender state (1 = Learn, 2 = Listen, 4 = Speak, 8 = Standby, 16 = Active).
`hello_time`	`uint(8)`	`3`		Interval between Hello messages, in seconds.
`hold_time`	`uint(8)`	`10`		Time a Hello stays valid, in seconds.
`priority`	`uint(8)`	`100`		Router priority within the group.
`group`	`uint(8)`	`0`		Standby group number.
`reserved`	`uint(8)`	`0`
`auth_data`	`bytes(8)`	`63 69 73 63 6f 00 00 00`		Clear-text authentication password (8 octets, default “cisco”).
`virtual_ip`	`ipv4`	`192.0.2.254`		Virtual IPv4 address of the group.

`op_code`

Value	Name
0 (0x00)	`hello`
1 (0x01)	`coup`
2 (0x02)	`resign`
3 (0x03)	`advertise`

`state`

Value	Name
0 (0x00)	`initial`
1 (0x01)	`learn`
2 (0x02)	`listen`
4 (0x04)	`speak`
8 (0x08)	`standby`
16 (0x10)	`active`

Next layer

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

Value	Protocol	Note
1 (0x01)	`hsrpv2`	re-decodes this layer

Sample templates

hsrpv1 — templates/protocols/fhrp/hsrpv1.wpg.yaml