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OSPF NETWORK TYPES
There are five different network types within which OSPF operates. The following list explains the characteristics of the OSPF network types:
Broadcast
- The Broadcast network type is the default for an OSPF enabled Ethernet interface.
- The Broadcast network type requires that a link support Layer 2 Broadcast capabilities.
- The Broadcast network type has a 10 second hello and 40 second dead timer.
- An OSPF Broadcast network type requires the use of a DR/BDR.
Non-Broadcast
- The Non-Broadcast network type is the default for OSPF enabled frame relay physical interfaces.
- Non-Broadcast networks requires the configuration of static neighbors; hello’s are sent via unicast.
- The Non-Broadcast network type has a 30 second hello and 120 second dead timer.
- An OSPF Non-Broadcast network type requires the use of a DR/BDR
Point-to-Point
- A Point-to-Point OSPF network type does not maintain a DR/BDR relationship.
- The Point-to-Point network type has a 10 second hello and 40 second dead timer.
- Point-to-Point network types are intended to be used between 2 directly connected routers.
Point-to-Multipoint Non-Broadcast
- Same as Point-to-Multipoint but requires static neighbors. Used on Non-broadcast layer 2 topologies.
- Gives you the ability to define link cost on a per neighbor basis.
Point-to-Multipoint
- OSPF treats Point-to-Multipoint networks as a collective of point-to-point links.
- Point-to-Multipoint networks do not maintain a DR/BDR relationship.
- Point-to-Multipoint networks advertise a hot route for all the frame-relay endpoints.
- The Point-to-Multipoint network type has a 30 second hello and 120 second dead timer.
Comparison Table: OSPF Network Types
To summarize , we can enumerate the OSPF Network Types in the below table –
MODE |
PREFERREDTOPOLOGY |
SUBNETADDRESS |
ADJACENCY |
RFC or CISCO |
| Non-Broadcast | Fully Meshed | Same | Manual configuration
DR/BDR elected |
RFC |
| Broadcast | Fully Meshed | Same | Automatic
DR/BDR elected |
Cisco |
| Point-to-multipoint | Partial Mesh or Star | Same | Automatic
No DR/BDR |
RFC |
| Point-to-multipoint
Non broadcast |
Partial Mesh or Star | Same | Manual configuration
No DR/BDR |
Cisco |
| Point-to-point | Partial Mesh or star, using sub interface | Different for each subnet | Automatic
No DR/BDR |
Cisco |
 |
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Download the table: OSPF Network Types
Continue Reading:
OSPF LSA Types The Ultimate Guide
OSPF Router Types: Detailed Explanation
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