OSPFv2 Message Format
OSPF Message Type
OSPF Authentication Type
- OSPF Hello packet
- OSPF database description packet
- OSPF link state request packet
- OSPF link state update packet
- OSPF link state confirm packet
OSPFv2 Message Format
┃ 8bit | 8bit | 16bit ┃
┏---------+------+-------------┓
┃Version=2| Type |Packet Length┃
┠---------+------+-------------┨
┃ Router ID ┃
┠------------------------------┨
┃ Area ID ┃
┠----------------+-------------┨
┃ Checksum | AuType ┃
┠----------------+-------------┨
┃ Authentication ┃
┠------------------------------┨
┃ Authentication ┃
┠------------------------------┨
┃ Data ┃
┗------------------------------┛
if AuType=2
┠--------+--------+----------------------------┨
┃ 0x0000 | Key ID | Authentication Data Length ┃
┠--------+--------+----------------------------┨
┃ Cryptographic Sequence Number ┃
┠----------------------------------------------┨
OSPF Message Type
| number | OSPF message type |
|---|---|
| 1 | Hello |
| 2 | database description |
| 3 | link state request |
| 4 | link state update |
| 5 | link state confirm |
OSPF Authentication Type
| number | OSPF Authentication type |
|---|---|
| 0 | null (no authentication) |
| 1 | simple password authentication (plaintext) |
| 2 | cryptographic checksum (MD5) |
OSPF Hello packet
┃ 8bit | 8bit | 8bit | 8bit ┃
┏---------+------+-------------------------┓
┃Version=2|Type=1| Packet Length ┃
┠---------+------+-------------------------┨
┃ Router ID ┃
┠------------------------------------------┨
┃ Area ID ┃
┠----------------+-------------------------┨
┃ Checksum | AuType ┃
┠----------------+-------------------------┨
┃ Authentication ┃
┠------------------------------------------┨
┃ Authentication ┃
┠------------------------------------------┨
┃ Network Mask ┃
┠----------------+--------+----------------┨
┃ Hello Interval | Option | Router Priority┃
┠----------------+--------+----------------┨
┃ Router Dead Interval ┃
┠------------------------------------------┨
┃ Designated Router ┃
┠------------------------------------------┨
┃ Back-up Designated Router ┃
┠------------------------------------------┨
┃ Neighbor ┃
┠------------------------------------------┨
┃ ... ┃
┠------------------------------------------┨
┃ Neighbor ┃
┗------------------------------------------┛
OSPF database description packet
┃ 8bit | 8bit | 8bit | 8bit ┃
┏---------+------+---------------------┓
┃Version=2|Type=2| Packet Length ┃
┠---------+------+---------------------┨
┃ Router ID ┃
┠--------------------------------------┨
┃ Area ID ┃
┠----------------+---------------------┨
┃ Checksum | AuType ┃
┠----------------+---------------------┨
┃ Authentication ┃
┠--------------------------------------┨
┃ Authentication ┃
┠----------------+--------+-----+-+-+--┨
┃ Interface MTU | Option |00000|I|M|MS┃
┠----------------+--------+-----+-+-+--┨
┃ DD Sequence Number ┃
┠--------------------------------------┨
┃ LSA Header ┃
┗--------------------------------------┛
I:Initial bit
M:More bit
MS:Master/Slave bit
OSPF link state request packet
┃ 8bit | 8bit | 16bit ┃
┏---------+------+---------------┓
┃Version=2|Type=3| Packet Length ┃
┠---------+------+---------------┨
┃ Router ID ┃
┠--------------------------------┨
┃ Area ID ┃
┠----------------+---------------┨
┃ Checksum | AuType ┃
┠----------------+---------------┨
┃ Authentication ┃
┠--------------------------------┨
┃ Authentication ┃
┠--------------------------------┨
┃ Link State Type ┃
┠--------------------------------┨
┃ Link State ID ┃
┠--------------------------------┨
┃ Advertising Router ┃
┠--------------------------------┨
┃ ... ┃
┠--------------------------------┨
┃ Link State Type ┃
┠--------------------------------┨
┃ Link State ID ┃
┠--------------------------------┨
┃ Advertising Router ┃
┗--------------------------------┛
OSPF link state update packet
┃ 8bit | 8bit | 16bit ┃
┏---------+------+---------------┓
┃Version=2|Type=4| Packet Length ┃
┠---------+------+---------------┨
┃ Router ID ┃
┠--------------------------------┨
┃ Area ID ┃
┠----------------+---------------┨
┃ Checksum | AuType ┃
┠----------------+---------------┨
┃ Authentication ┃
┠--------------------------------┨
┃ Authentication ┃
┠--------------------------------┨
┃ Number of LSA ┃
┠--------------------------------┨
┃ LSA ┃
┗--------------------------------┛
OSPF link state confirm packet
┃ 8bit | 8bit | 16bit ┃
┏---------+------+---------------┓
┃Version=2|Type=4| Packet Length ┃
┠---------+------+---------------┨
┃ Router ID ┃
┠--------------------------------┨
┃ Area ID ┃
┠----------------+---------------┨
┃ Checksum | AuType ┃
┠----------------+---------------┨
┃ Authentication ┃
┠--------------------------------┨
┃ Authentication ┃
┠--------------------------------┨
┃ LSA Header ┃
┗--------------------------------┛