Operation Manual – IPv4 Routing
H3C S3610&S5510 Series Ethernet Switches
Chapter 3 OSPF Configuration
3-12
3.1.5 OSPF Packet Formats
OSPF packets are directly encapsulated into IP packets. OSPF has the IP protocol
number 89. The OSPF packet format is shown below (taking a LSU packet as an
example).
Figure 3-8
OSPF packet format
I. OSPF packet header
OSPF packets are classified into five types that have the same packet header, as
shown below.
Figure 3-9
OSPF packet header
z
Version: OSPF version number, which is 2 for OSPFv2.
z
Type: OSPF packet type from 1 to 5, corresponding with hello, DD, LSR, LSU and
LSAck respectively.
z
Packet length: Total length of the OSPF packet in bytes, including the header.
z
Router ID: ID of the advertising router.
z
Area ID: ID of the area where the advertising router resides.
z
Checksum: Checksum of the message.
z
Autype: Authentication type from 0 to 2, corresponding with non-authentication,
simple (plaintext) authentication and MD5 authentication respectively.
z
Authentication: Information determined by authentication type. It is not defined for
authentication type 0. It is defined as password information for authentication type
1, and defined as Key ID, MD5 authentication data length and sequence number
for authentication type 2.
Note:
MD5 authentication data is added following an OSPF packet rather than contained in
the Authentication field.
