OSPF Network Types

The network type is determined by layer-2 encapsulation on the interface:

sh ip ospf interface
 FastEthernet0/0 is up, line protocol is up
 Internet Address 10.10.10.10/24, Area 0
 Process ID 1, Router ID 10.10.10.10, Network Type POINT_TO_POINT, Cost: 10
 Transmit Delay is 1 sec, State POINT_TO_POINT,
 Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
 oob-resync timeout 40
 Hello due in 00:00:00
 Supports Link-local Signaling (LLS)
 Index 1/1, flood queue length 0
 Next 0x0(0)/0x0(0)
 Last flood scan length is 0, maximum is 0
 Last flood scan time is 0 msec, maximum is 0 msec
 Neighbor Count is 0, Adjacent neighbor count is 0
 Suppress hello for 0 neighbor(s)

Network type Broadcast:

• Default on LAN interfaces
• Discovers neighbors automatically
• Uses DR/BDR
• Intervals 10/40
• (config-if)#ip ospf network broadcast

Network type Non-Broadcast

• Default on FrameRelay physical and multipoint interfaces
• Does NOT discover neighbors automatically
• Intervals 30/120
• Static neighbor configuration
• (config-if)#neighbor 10.10.10.10 [priority priority] (ospf command)

Frame-Relay Network Type:

• Physical or Multipoint interfaces can be used to connect to the FrameRelay cloud which results in different network types

Network type Point-to-Point:

• Default on point-to-point (hdli/ppp) interfaces
• Discovers neighbors dynamically
• does NOT use DR/BDR
• Intervals 10/40
• (config-if)#ip ospf network point-to-point

Network type Point-to-Multipoint:

• Not the default on any interface
• Discovers neighbors dynamically
• does NOT elect DR/BDR
• Intervals 30/120
• (config-if)#ip ospf network point-to-multipoint

Network type Point-to-Multipoint Non-Broadcast:

• Not the default on any interface
• Does NOT discover neighbors automatically
• does NOT elect DR/BDR
• Cost to reach neighbour
• (config-if)#ip ospf network point-to-multipoint non-broadcast
• Network type point-* doesn’t use DR/BDR
• Non-Broadcast doesn’t do dynamic neighbor discovery
• Only Brocastcast and Point-to-Point use fast timers 10/40