OSPF DR election configuration example
Network requirements
Enable OSPF on Switches A, B, C, and D on the same network.
Configure Switch A as the DR, and configure Switch C as the BDR.
Figure 27: Network diagram
Configuration procedure
Configure IP addresses for interfaces. (Details not shown.)
Enable OSPF:
# Configure Switch A.
<SwitchA> system-view [SwitchA] router id 1.1.1.1 [SwitchA] ospf [SwitchA-ospf-1] area 0 [SwitchA-ospf-1-area-0.0.0.0] network 192.168.1.0 0.0.0.255 [SwitchA-ospf-1-area-0.0.0.0] quit [SwitchA-ospf-1] quit
# Configure Switch B.
<SwitchB> system-view [SwitchB] router id 2.2.2.2 [SwitchB] ospf [SwitchB-ospf-1] area 0 [SwitchB-ospf-1-area-0.0.0.0] network 192.168.1.0 0.0.0.255 [SwitchB-ospf-1-area-0.0.0.0] quit [SwitchB-ospf-1] quit
# Configure Switch C.
<SwitchC> system-view [SwitchC] router id 3.3.3.3 [SwitchC] ospf [SwitchC-ospf-1] area 0 [SwitchC-ospf-1-area-0.0.0.0] network 192.168.1.0 0.0.0.255 [SwitchC-ospf-1-area-0.0.0.0] quit [SwitchC-ospf-1] quit
# Configure Switch D.
<SwitchD> system-view [SwitchD] router id 4.4.4.4 [SwitchD] ospf [SwitchD-ospf-1] area 0 [SwitchD-ospf-1-area-0.0.0.0] network 192.168.1.0 0.0.0.255 [SwitchD-ospf-1-area-0.0.0.0] quit [SwitchD-ospf-1] return
# Display OSPF neighbor information of Switch A.
[SwitchA] display ospf peer verbose OSPF Process 1 with Router ID 1.1.1.1 Neighbors Area 0.0.0.0 interface 192.168.1.1(Vlan-interface1)'s neighbors Router ID: 2.2.2.2 Address: 192.168.1.2 GR State: Normal State: 2-Way Mode: None Priority: 1 DR: 192.168.1.4 BDR: 192.168.1.3 MTU: 0 Options is 0x02 (-|-|-|-|-|-|E|-) Dead timer due in 38 sec Neighbor is up for 00:01:31 Authentication Sequence: [ 0 ] Router ID: 3.3.3.3 Address: 192.168.1.3 GR State: Normal State: Full Mode: Nbr is Master Priority: 1 DR: 192.168.1.4 BDR: 192.168.1.3 MTU: 0 Options is 0x02 (-|-|-|-|-|-|E|-) Dead timer due in 31 sec Neighbor is up for 00:01:28 Authentication Sequence: [ 0 ] Router ID: 4.4.4.4 Address: 192.168.1.4 GR State: Normal State: Full Mode: Nbr is Master Priority: 1 DR: 192.168.1.4 BDR: 192.168.1.3 MTU: 0 Options is 0x02 (-|-|-|-|-|-|E|-) Dead timer due in 31 sec Neighbor is up for 00:01:28 Authentication Sequence: [ 0 ]The output shows that Switch D is the DR and Switch C is the BDR.
Configure router priorities on interfaces:
# Configure Switch A.
[SwitchA] interface vlan-interface 1 [SwitchA-Vlan-interface1] ospf dr-priority 100 [SwitchA-Vlan-interface1] quit
# Configure Switch B.
[SwitchB] interface vlan-interface 1 [SwitchB-Vlan-interface1] ospf dr-priority 0 [SwitchB-Vlan-interface1] quit
# Configure Switch C.
[SwitchC] interface vlan-interface 1 [SwitchC-Vlan-interface1] ospf dr-priority 2 [SwitchC-Vlan-interface1] quit
# Display neighbor information of Switch D.
<SwitchD> display ospf peer verbose OSPF Process 1 with Router ID 4.4.4.4 Neighbors Area 0.0.0.0 interface 192.168.1.4(Vlan-interface1)'s neighbors Router ID: 1.1.1.1 Address: 192.168.1.1 GR State: Normal State: Full Mode:Nbr is Slave Priority: 100 DR: 192.168.1.4 BDR: 192.168.1.3 MTU: 0 Options is 0x02 (-|-|-|-|-|-|E|-) Dead timer due in 31 sec Neighbor is up for 00:11:17 Authentication Sequence: [ 0 ] Router ID: 2.2.2.2 Address: 192.168.1.2 GR State: Normal State: Full Mode:Nbr is Slave Priority: 0 DR: 192.168.1.4 BDR: 192.168.1.3 MTU: 0 Options is 0x02 (-|-|-|-|-|-|E|-) Dead timer due in 35 sec Neighbor is up for 00:11:19 Authentication Sequence: [ 0 ] Router ID: 3.3.3.3 Address: 192.168.1.3 GR State: Normal State: Full Mode:Nbr is Slave Priority: 2 DR: 192.168.1.4 BDR: 192.168.1.3 MTU: 0 Options is 0x02 (-|-|-|-|-|-|E|-) Dead timer due in 33 sec Neighbor is up for 00:11:15 Authentication Sequence: [ 0 ]The output shows that the DR and BDR are not changed, because the priority settings do not take effect immediately.
Restart OSPF process:
# Restart the OSPF process of Switch D.
<SwitchD> reset ospf 1 process Warning : Reset OSPF process? [Y/N]:y
# Display neighbor information of Switch D.
<SwitchD> display ospf peer verbose OSPF Process 1 with Router ID 4.4.4.4 Neighbors Area 0.0.0.0 interface 192.168.1.4(Vlan-interface1)'s neighbors Router ID: 1.1.1.1 Address: 192.168.1.1 GR State: Normal State: Full Mode: Nbr is Slave Priority: 100 DR: 192.168.1.1 BDR: 192.168.1.3 MTU: 0 Options is 0x02 (-|-|-|-|-|-|E|-) Dead timer due in 39 sec Neighbor is up for 00:01:40 Authentication Sequence: [ 0 ] Router ID: 2.2.2.2 Address: 192.168.1.2 GR State: Normal State: 2-Way Mode: None Priority: 0 DR: 192.168.1.1 BDR: 192.168.1.3 MTU: 0 Options is 0x02 (-|-|-|-|-|-|E|-) Dead timer due in 35 sec Neighbor is up for 00:01:44 Authentication Sequence: [ 0 ] Router ID: 3.3.3.3 Address: 192.168.1.3 GR State: Normal State: Full Mode: Nbr is Slave Priority: 2 DR: 192.168.1.1 BDR: 192.168.1.3 MTU: 0 Options is 0x02 (-|-|-|-|-|-|E|-) Dead timer due in 39 sec Neighbor is up for 00:01:41 Authentication Sequence: [ 0 ]If the neighbor state is full, Switch D has established an adjacency with the neighbor. If the neighbor state is 2-way, the two switches are not the DR or the BDR, and they do not exchange LSAs.
# Display OSPF interface information.
[SwitchA] display ospf interface OSPF Process 1 with Router ID 1.1.1.1 Interfaces Area: 0.0.0.0 IP Address Type State Cost Pri DR BDR 192.168.1.1 Broadcast DR 1 100 192.168.1.1 192.168.1.3 [SwitchB] display ospf interface OSPF Process 1 with Router ID 2.2.2.2 Interfaces Area: 0.0.0.0 IP Address Type State Cost Pri DR BDR 192.168.1.2 Broadcast DROther 1 0 192.168.1.1 192.168.1.3The interface state DROther means the interface is not the DR or BDR.