Table of Contents
Configuring OSPF router priority
Router priority is configured to make a specific router the DR/BDR on a multi-access network such as Ethernet. To configure the router priority, enter the following command in interface configuration mode.
(config-if)#ip ospf priority <priority>
<interface-name> : interface-name
<priority> : priority.0～255
On Cisco, the router priority value defaults to 1. 0 is a special value that means it will not be DR/BDR. Configure the router you want to be the DR with the highest value and the router you want to be the BDR with the second highest value.
However, configuring the priority does not immediately change the DR/BDR. If there is an existing DR, it will not change even if a router with a higher priority is added later. After configuring the priority, clear the OSPF process once on the router that is the current DR/BDR.
#clear ip ospf process
For more information on DR/BDR, please see the following articles.
Verifying OSPF router priority
To verify the router priority, the following show command is easy to understand.
- show ip ospf neighbor
- show ip ospf interface
show ip ospf neighbor
You can use the show ip ospf neighbor command to verify the router priority of the neighbor.
R1#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 192.168.12.2 1 FULL/DR 00:00:32 192.168.12.2 Ethernet0/0 192.168.13.3 0 FULL/ - 00:00:31 192.168.13.3 Serial1/0
show ip ospf neighborコマンドでは、コマンドを実行しているルータ自身のプライオリティはわかりません。
show ip ospf interface
The show ip ospf interface command will show you the details of OSPF enabled interfaces. You can verify the router priority value and the router that is the current DR/BDR.
R1#show ip ospf interface ethernet0/0 Ethernet0/0 is up, line protocol is up Internet Address 192.168.12.1/24, Area 0 Process ID 1, Router ID 192.168.13.1, Network Type BROADCAST, Cost: 10 Transmit Delay is 1 sec, State BDR, Priority 1 Designated Router (ID) 192.168.12.2, Interface address 192.168.12.2 Backup Designated router (ID) 192.168.13.1, Interface address 192.168.12.1 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 1, maximum is 3 Last flood scan time is 0 msec, maximum is 4 msec Neighbor Count is 1, Adjacent neighbor count is 1 Adjacent with neighbor 192.168.12.2 (Designated Router) Suppress hello for 0 neighbor(s)
How the OSPF works
- OSPF Overview
- OSPF process flow
- OSPF Router ID : Identify OSPF routers
- What if the router ID of the OSPF router is duplicated?
- OSPF Neighbor and Adjacency
- OSPF DR/BDR
- How show ip ospf neighbor looks on Ethernet
- OSPF Network Type : Classification of OSPF-enabled interfaces
- Synchronization process of OSPF LSDB
- Problems with large-scale OSPF network
- OSPF Area – Inside the area, in detail; outside the area, just a summary
- OSPF Router Type
- OSPF LSA Type
- OSPF Area Type
- OSPF Basic Configuration and Verification Commands
- Details of enabling OSPF on the interface
- OSPF Advertising Loopback Interface
- Configuring and Verifying OSPF Hello/Dead interval
- OSPF Cost Configuration and Verification
- Configuring and Verifying OSPF Router Priority
- Configuring OSPF Neighbor Authentication
- Neighbor Authentication over Virtual-link
- OSPF Configuring and Verifying Stub area [Cisco]
- OSPF Stub Area Configuration Example [Cisco]
- OSPF default route generation : default-information originate command
- Configuration Example of OSPF default route generation : stub area
- OSPF Virtual-Link : Virtual area 0 point-to-point link
- Configuring and Verifying OSPF Virtual-link [Cisco]
- OSPF Virtual-link Configuration Example [Cisco]
- OSPF Virtual-link for discontinuous backbone configuration example
- OSPF Route Summary and Configuration
- Cisco OSPF Route Summary Configuration Example
- OSPF Route Type Preference
- Why the OSPF neighbor state gets stuck in Exstart?
- OSPF packet type and header format
- OSPF Hello Packet
- OSPF DD(Database Description) Packet
- OSPF LSR(Link State Request) Packet
- OSPF LSU(Link State Update) Packet
- OSPF LSAck(Link State Acknowledgement) Packet
- Limitation of OSPF redistribution routes – redistribute maximum-prefix command
- Overview of LSA Filters for OSPF – Filter LSA Type 3/Type 5
- Configuration example of LSA type 3 filter
- Configuration example of LSA type 5 filter
- OSPFv3 Configuration Example [Cisco]
- Configuration Example of OSPFv3 Route Summary [Cisco]