OSPF Network Type – Point-to-Point

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Points to remember about Point-to-Point OSPF network type.

1. No Designated Router (DR) and Back Designated Router(BDR) election.
2. Uses multicast to send OSPF hello.
3. Default network type on HDLC, PPP and point-to-point NBMA.
4. Only supports adjacency of two neighbors on a segment.

                       S0/1       
     .-----.           12.0.0.2/30  .-----.
     | R01 |<--------------------->| R02 |
     '-----' S0/1                   '-----'
             12.0.0.1/30  

No DR/BDR election occurs.

*Mar  1 00:11:25.127: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/1, changed state to up
*Mar  1 00:11:25.139: OSPF: Interface Serial0/1 going Up
*Mar  1 00:11:25.151: OSPF: 2 Way Communication to 1.1.1.1 on Serial0/1, state 2WAY
*Mar  1 00:11:25.151: OSPF: Send DBD to 1.1.1.1 on Serial0/1 seq 0x36C opt 0x52 flag 0x7 len 32
*Mar  1 00:11:25.155: OSPF: Rcv DBD from 1.1.1.1 on Serial0/1 seq 0x10BA opt 0x52 flag 0x7 len 32  mtu 1500 state EXSTART
*Mar  1 00:11:25.155: OSPF: First DBD and we are not SLAVE
*Mar  1 00:11:25.155: OSPF: Rcv DBD from 1.1.1.1 on Serial0/1 seq 0x36C opt 0x52 flag 0x2 len 112  mtu 1500 state EXSTART
*Mar  1 00:11:25.155: OSPF: NBR Negotiation Done. We are the MASTER
*Mar  1 00:11:25.155: OSPF: Send DBD to 1.1.1.1 on Serial0/1 seq 0x36D opt 0x52 flag 0x3 len 52
*Mar  1 00:11:25.155: OSPF: Rcv DBD from 1.1.1.1 on Serial0/1 seq 0x36D opt 0x52 flag 0x0 len 32  mtu 1500 state EXCHANGE
*Mar  1 00:11:25.155: OSPF: Send DBD to 1.1.1.1 on Serial0/1 seq 0x36E opt 0x52 flag 0x1 len 32
*Mar  1 00:11:25.155: OSPF: Send LS REQ to 1.1.1.1 length 48 LSA count 4
*Mar  1 00:11:25.155: OSPF: Rcv DBD from 1.1.1.1 on Serial0/1 seq 0x36E opt 0x52 flag 0x0 len 32  mtu 1500 state EXCHANGE
*Mar  1 00:11:25.159: OSPF: Exchange Done with 1.1.1.1 on Serial0/1
*Mar  1 00:11:25.159: OSPF: Rcv LS UPD from 1.1.1.1 on Serial0/1 length 184 LSA count 4
*Mar  1 00:11:25.159: OSPF: Build router LSA for area 0, router ID 2.2.2.2, seq 0x80000008
*Mar  1 00:11:25.159: OSPF: Synchronized with 1.1.1.1 on Serial0/1, state FULL
*Mar  1 00:11:25.159: %OSPF-5-ADJCHG: Process 1, Nbr 1.1.1.1 on Serial0/1 from LOADING to FULL, Loading Done
*Mar  1 00:11:25.659: OSPF: Rcv LS UPD from 1.1.1.1 on Serial0/1 length 76 LSA count 1
*Mar  1 00:11:30.163: OSPF: Build router LSA for area 0, router ID 2.2.2.2, seq 0x80000009

The OSPF neighbor indicates no DR/BDR for the segment with the dash symbol (means null) under the State column.

R2#sh ip ospf neighbor

Neighbor ID     Pri   State           Dead Time   Address         Interface
1.1.1.1           0   FULL/  -        00:00:39    12.0.0.1        Serial0/1

The command “show IP ospf interface” shows all the interface running OSPF. The output displays important information like network type, hello intervals including dead, wait and retransmits.

R2#sh ip ospf interface  
Serial0/1 is up, line protocol is up 
  Internet Address 12.0.0.2/30, Area 0 
  Process ID 1, Router ID 2.2.2.2, Network Type POINT_TO_POINT, Cost: 64
  Enabled by interface config, including secondary ip addresses
  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 00:00:09
  Supports Link-local Signaling (LLS)
  Index 2/2, flood queue length 0
  Next 0x0(0)/0x0(0)
  Last flood scan length is 1, maximum is 1
  Last flood scan time is 0 msec, maximum is 0 msec
  Neighbor Count is 1, Adjacent neighbor count is 1 
    Adjacent with neighbor 1.1.1.1
  Suppress hello for 0 neighbor(s)

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