D-Link DGS-3324SRi User Manual page 114

D-Link DGS-3324SRi Intelligent Stackable Gigabit Ethernet Switch
OSPF Packet Header
Version No.
Field
Version No.
Type
Packet Length
Router ID
Area ID
Checksum
Authentication Type
Authentication
The Hello Packet
Hello packets are OSPF packet type 1. They are sent periodically on all interfaces, including virtual links, in
order to establish and maintain neighbor relationships. In addition, Hello Packets are multicast on those physical
networks having a multicast or broadcast capability, enabling dynamic discovery of neighboring routers.
All routers connected to a common network must agree on certain parameters such as the Network Mask, the
Hello Interval, and the Router Dead Interval. These parameters are included in hello packets, so that differences
can inhibit the forming of neighbor relationships. A detailed explanation of the receive processing for Hello
packets, so that differences can inhibit the forming of neighbor relationships.
The format of the Hello packet is shown below:
Type
Router ID
Area ID
Checksum
Authentication
Authentication
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.
A 64-bit field used by the authentication scheme.
OSPF Packet Header
99
Packet Length
Authentication Type