Ospf Packet Formats - D-Link Xstack DGS-3300 Series User Manual

xStack DGS/DXS-3300 Series Layer 3 Stackable Gigabit Ethernet Switch User Manual
• Exchange − Routers will describe their entire link-state database by sending database description packets.
• Loading − The routers are finalizing the information exchange. Routers have link-state request list and a link-
state retransmission list. Any information that looks incomplete or outdated will be put on the request list. Any
update that is sent will be put on the retransmission list until it is acknowledged.
• Full − The adjacency is now complete. The neighboring routers are fully adjacent. Adjacent routers will have the
same link-state database.
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
•
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