​​Summary:

1. Determine which router became the DR

2. Elect "Tie" as the DR moving forward

 

 

Knowledge:

1. The only way to change the DR or BDR is to reload or re-start the ospf process because DR or BDR do not preempt 


2. In general determining DR or BDR is not extremely critical, but in a non-broadcase multi-access network (cloud), it's important to keep the hub as DR the entire time and set the spoke routers' priority to 0


3. point to point connection doesn't elect DR and BDR

 

 

 

1. Determine which router became the DR

 

Shoe:

Shoe#sh ip ospf neighbor   !--------------------------------------------------------------------------- since this a point to point router, this command didn't tell much

Neighbor ID     Pri   State           Dead Time   Address         Interface
3.3.3.3           0   FULL/  -        00:00:39    10.1.2.1        Serial1/0



Shoe#sh ip ospf interface
Serial1/0 is up, line protocol is up !-------------------------------------------------------------------- this tells s1/0 is running ospf
  Internet Address 10.1.2.2/24, Area 0
  Process ID 1, Router ID 4.4.4.4, Network Type POINT_TO_POINT, Cost: 64 !------ network type dictates how ospf communicates
  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 00:00:05
  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 3.3.3.3
  Suppress hello for 0 neighbor(s)
FastEthernet0/0 is up, line protocol is up
  Internet Address 10.1.3.1/24, Area 0
  Process ID 1, Router ID 4.4.4.4, Network Type BROADCAST, Cost: 10 !------------------ network type dictates how ospf communicates
  Transmit Delay is 1 sec, State DR, Priority 1            !---------------------------------------------- on the Ethernet, it's elected as DR
  Designated Router (ID) 4.4.4.4, Interface address 10.1.3.1
  No backup designated router on this network
  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 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)


Sock: (current DR)

Sock#sho ip ospf neighbor

Neighbor ID     Pri   State           Dead Time   Address         Interface
1.1.1.1           1   FULL/BDR        00:00:31    10.1.1.1        FastEthernet0/0
2.2.2.2           1   FULL/DROTHER    00:00:35    10.1.1.2        FastEthernet0/0
4.4.4.4           0   FULL/  -        00:00:30    10.1.2.2        Serial1/0


Sock#sh ip ospf interface fa0/0
FastEthernet0/0 is up, line protocol is up
  Internet Address 10.1.1.3/24, Area 0
  Process ID 1, Router ID 3.3.3.3, Network Type BROADCAST, Cost: 10
  Transmit Delay is 1 sec, State DR, Priority 1  !-------------------------------------------------------------------------------------- yes, this is current DR
  Designated Router (ID) 3.3.3.3, Interface address 10.1.1.3
  Backup Designated router (ID) 1.1.1.1, Interface address 10.1.1.1
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    oob-resync timeout 40
    Hello due in 00:00:07
  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 2, Adjacent neighbor count is 2
    Adjacent with neighbor 1.1.1.1  (Backup Designated Router)
    Adjacent with neighbor 2.2.2.2
  Suppress hello for 0 neighbor(s)
Sock#


Belt:

Belt#show ip ospf neighbor

Neighbor ID     Pri   State           Dead Time   Address         Interface
1.1.1.1           1   FULL/BDR        00:00:34    10.1.1.1        FastEthernet0/0
3.3.3.3           1   FULL/DR         00:00:31    10.1.1.3        FastEthernet0/0
Belt#


Tie: (current BDR)

Tie#sh ip ospf neighbor

Neighbor ID     Pri   State           Dead Time   Address         Interface
2.2.2.2           1   FULL/DROTHER    00:00:37    10.1.1.2        FastEthernet0/0
3.3.3.3           1   FULL/DR         00:00:33    10.1.1.3        FastEthernet0/0

 

 

 

 

2. Elect "Tie" as the DR moving forward (see knowledge 1)

 

 

Tie:

int fa0/0
 ip ospf priority 10


Belt: (restart ospf process)

Belt#clear ip ospf process
Reset ALL OSPF processes? [no]: y
Belt#

Belt#sh ip ospf neighbor

Neighbor ID     Pri   State           Dead Time   Address         Interface
1.1.1.1          10   FULL/BDR        00:00:38    10.1.1.1        FastEthernet0/0
3.3.3.3           1   FULL/DR         00:00:35    10.1.1.3        FastEthernet0/0
Belt#


Tie:

Tie#sh ip ospf interface
FastEthernet0/0 is up, line protocol is up
  Internet Address 10.1.1.1/24, Area 0
  Process ID 1, Router ID 1.1.1.1, Network Type BROADCAST, Cost: 10
  Transmit Delay is 1 sec, State BDR, Priority 10  !------------------------------------------------------showing as BDR even with higher priority
  Designated Router (ID) 3.3.3.3, Interface address 10.1.1.3
  Backup Designated router (ID) 1.1.1.1, Interface address 10.1.1.1
  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 1
  Last flood scan time is 0 msec, maximum is 0 msec
  Neighbor Count is 2, Adjacent neighbor count is 2
    Adjacent with neighbor 2.2.2.2
    Adjacent with neighbor 3.3.3.3  (Designated Router)
  Suppress hello for 0 neighbor(s)
Tie#



Sock: (restart ospf process)


Sock#clear ip ospf process
Sock#sh ip ospf neighbor

Neighbor ID     Pri   State           Dead Time   Address         Interface
1.1.1.1          10   FULL/DR         00:00:30    10.1.1.1        FastEthernet0/0
2.2.2.2           1   FULL/BDR        00:00:35    10.1.1.2        FastEthernet0/0
4.4.4.4           0   FULL/  -        00:00:39    10.1.2.2        Serial1/0
Sock#

Tie: (now to back to Tie, and confirm)

Tie#sh ip ospf interface
FastEthernet0/0 is up, line protocol is up
  Internet Address 10.1.1.1/24, Area 0
  Process ID 1, Router ID 1.1.1.1, Network Type BROADCAST, Cost: 10
  Transmit Delay is 1 sec, State DR, Priority 10 !--------------------------------------------------yes, Tie is now DR
  Designated Router (ID) 1.1.1.1, Interface address 10.1.1.1
  Backup Designated router (ID) 2.2.2.2, Interface address 10.1.1.2
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    oob-resync timeout 40
    Hello due in 00:00:05
  Supports Link-local Signaling (LLS)
  Index 1/1, 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 2, Adjacent neighbor count is 2
    Adjacent with neighbor 2.2.2.2  (Backup Designated Router)
    Adjacent with neighbor 3.3.3.3
  Suppress hello for 0 neighbor(s)
Tie#

 

 

 

-Yu