Ospf Packet Formats - D-Link DXS-3326GSR Manual

Adjacencies on Point-to-Point Interfaces
OSPF Routers that are linked using point-to-point interfaces (such as serial links) will always form adjacencies. The
concepts of DR and BDR are unnecessary.

OSPF Packet Formats

All OSPF packet types begin with a standard 24-byte header and there are five packet types. The header is described first,
and each packet type is described in a subsequent section.
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
DXS-3326GSR Gigabit Layer 3 Switch
OSPF Packet Header
Type
Version No.
Checksum
Figure 7- 18. 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
Packet Length
Router ID
Area ID
Authentication Type
Authentication
Authentication
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