BGP OPEN (`bgp_open`)

Layer: Application and control
Header: variable length

Reached from

Lower layer	Selector	Value
`bgp`	`type`	1 (0x01)

Fields

Field	Type	Default	Auto	Description
`version`	`uint(8)`	`4`		BGP version (4).
`my_as`	`uint(16)`	`65001`		Autonomous system number of the sender (23456 = AS_TRANS for 4-octet AS).
`hold_time`	`uint(16)`	`180`		Proposed hold time, in seconds (0 or at least 3).
`bgp_identifier`	`ipv4`	`192.0.2.1`		BGP identifier (router ID) of the sender.
`opt_params_length`	`uint(8)`		Length of the header in octets (`-10`)	Length of the optional parameters, in octets (Auto).
`opt_params`	`tlv` — `opt_params_length` octets	1 items		Optional parameters (type 2 = capabilities).

`opt_params`

Type 8 bits, length 8 bits.
The length counts the value only.
Unknown types are kept as raw value octets.

Type	Name	Value fields	Description
2 (0x02)	`capabilities`	`capabilities`

`opt_params` › `capabilities`

Field	Type	Default	Auto	Description
`capabilities`	`tlv` — rest of the PDU

`opt_params` › `capabilities` › `capabilities`

Type 8 bits, length 8 bits.
The length counts the value only.
Unknown types are kept as raw value octets.

Type	Name	Value fields	Description
1 (0x01)	`multiprotocol`	`afi`, `reserved`, `safi`
2 (0x02)	`route_refresh`
64 (0x40)	`graceful_restart`	`restart_flags`, `restart_time`, `address_families`
65 (0x41)	`four_octet_as`	`asn`
69 (0x45)	`add_path`	`address_families`
70 (0x46)	`enhanced_route_refresh`
128 (0x80)	`route_refresh_cisco`

`opt_params` › `capabilities` › `capabilities` › `multiprotocol`

Field	Type	Default	Auto	Description
`afi`	`uint(16)`
`reserved`	`uint(8)`
`safi`	`uint(8)`

`opt_params` › `capabilities` › `capabilities` › `graceful_restart`

Field	Type	Default	Auto	Description
`restart_flags`	`uint(4)`
`restart_time`	`uint(12)`
`address_families`	`bytes` — rest of the PDU

`opt_params` › `capabilities` › `capabilities` › `four_octet_as`

Field	Type	Default	Auto	Description
`asn`	`uint(32)`

`opt_params` › `capabilities` › `capabilities` › `add_path`

Field	Type	Default	Auto	Description
`address_families`	`bytes` — rest of the PDU

Constraints

Level	Rule
warning	`version` = 4

Sample templates

bgp-open — templates/protocols/routing/bgp-open.wpg.yaml