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	PREFERRED TOPOLOGY	SUBNET ADDRESS	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

Download the table: OSPF Network Types

Continue Reading:

OSPF LSA Types The Ultimate Guide

OSPF Router Types: Detailed Explanation

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ABOUT THE AUTHOR

Rashmi Bhardwaj

Founder of AAR TECHNOSOLUTIONS, Rashmi is an evangelist for IT and technology. With more than 12 years in the IT ecosystem, she has been supporting multi domain functions across IT & consultancy services, in addition to Technical content making.

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