D-Link xStack DES-3800 Series User Manual page 137

All OSPF packets (except for Hello packets) forward link-state advertisements. Link-State Update
packets, for example, flood advertisements throughout the OSPF routing domain.
OSPF packet header
•
Hello packet
•
Database Description packet
•
Link-State Request packet
•
Link-State Update packet
•
Link-State Acknowledgment packet
•
OSPF Packet Header
Every OSPF packet is preceded by a common 24-byte header. This header contains the information
necessary for a receiving router to determine if the packet should be accepted for further processing.
The format of the OSPP packet header is shown below:
Field
Version No.
Type
Packet Length
Router ID
Area ID
Checksum
Authentication Type
xStack DES-3800 Series Layer 3 Stackable Fast Ethernet Managed Switch
OSPF Packet Header
Version No.
Checksum
Figure 8- 16. OSPF Packet Header Format
Description
The OSPF version number
The OSPF packet type. The OSPF packet types are as follows: Type
Description Hello Database Description Link-State Request Link-State
Update Link-State Acknowledgment
The length of the packet in bytes. This length includes the 24-byte
header.
The Router ID of the packet's source.
A 32-bit number identifying the area that this packet belongs to. All
OSPF packets are associated with a single area. Packets traversing a
virtual link are assigned the backbone Area ID of 0.0.0.0
A standard IP checksum that includes all of the packet's contents
except for the 64-bit authentication field.
The type of authentication to be used for the packet.
Type
Router ID
Area ID
Authentication Type
Authentication
Authentication
121
Packet Length