Configuring VRRP on a Core Switch Example

VRRP can be configured on a core switch to provide a redundant default gateway using a virtual IP address shared between master and backup routers.

Step-by-

Step VRR

P Configuration Example1.

Access the Switch

Connect to the core switch via console, SSH, or Telnet and enter privileged mode: CodeCopyenableconfigure terminal 2.

Configure VLAN Interfaces

Assign I

P addresses to the VLAN interfaces that will participate in VRRP. For example, for VLAN 10: CodeCopyinterface Vlan10 ip address 192. 168.

10. 2 255. 255.

255. 0 On the backup switch: CodeCopyinterface Vlan10 ip address 192. 168.

10. 3 255. 255.

255. 0 Ensure VLANs are created and trunk ports are configured between switches if needed. 3.

Create VRRP Group and Assign Virtual IP

Define the VRRP group and the virtual IP address that hosts will use as their default gateway: CodeCopyvrrp 10 ip 192. 168. 10.

1 This command is applied on both master and backup switches. 4.

Set VRRP Priority

Configure the priority to determine which switch becomes the master. Higher priority wins: CodeCopyvrrp 10 priority 110! Master switchvrrp 10 priority 100!

Backup switch The default priority is 100 if not explicitly set. 5. Enable Preemption (Optional)Preemption allows a higher-priority switch to take over as master if it comes online: CodeCopyvrrp 10 preempt To disable preemption: CodeCopyno vrrp 10 preempt Preemption is enabled by default.

6. Configure Authentication (Optional)For security, configure MD5 authentication: CodeCopyvrrp 10 authentication md5 key-string CISCO Apply the same key on both switches. 7.

Verify VRRP Configuration

Check the VRRP status and ensure the master and backup roles are correctly assigned: CodeCopyshow vrrpshow vrrp brief all You should see the master switch with the higher priority and the virtual IP active. 8.

Test Failover

Simulate a master switch failure by shutting down the VLAN interface: CodeCopyinterface Vlan10 shutdown Verify that the backup switch takes over the virtual IP and resumes forwarding traffic. NotesVRRP uses a virtual MAC address in the format 0000. 5E00.

01XX, where XX is the group number in hexadecimal. Ensure all participating switches are in the same subnet and VLAN. Save the configuration to persist after a reboot: CodeCopywrite memory This configuration ensures high availability for the default gateway, allowing hosts to maintain connectivity even if the primary switch fails.