Tag: administrative distance

Static routes are a simple and effective way to control traffic flow in a network. However, in more complex scenarios, you may need to use administrative distance and floating static routes to create backup paths or prioritize certain routes. In this guide, we’ll walk you through the steps to configure static routes with administrative distance and floating static routes on a Cisco router.

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What Are Administrative Distance and Floating Static Routes?

• Administrative Distance (AD): A value (0–255) that routers use to determine the trustworthiness of a route. Lower values are preferred.
  • Static routes have a default AD of 1.
• Floating Static Routes: Backup static routes with a higher AD than the primary route. They “float” below the primary route and become active only if the primary route fails.

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Step 1: Access the Router’s CLI

1. Connect to your router via console cable, Telnet, or SSH.
2. Enter privileged EXEC mode:
   Router> enable
Router#

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Step 2: Configure Primary Static Routes

1. Enter global configuration mode:
   Router# configure terminal
Router(config)#
2. Configure the primary static route:
   Router(config)# ip route 192.168.2.0 255.255.255.0 10.0.0.2
   • 192.168.2.0 is the destination network.
   • 255.255.255.0 is the subnet mask.
   • 10.0.0.2 is the next-hop IP address.
   • By default, this route has an AD of 1.

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Step 3: Configure Floating Static Routes

1. Configure a floating static route with a higher AD (e.g., 10):
   Router(config)# ip route 192.168.2.0 255.255.255.0 10.0.0.3 10
   • 10.0.0.3 is the backup next-hop IP address.
   • 10 is the AD for this route.
   • This route will remain inactive unless the primary route fails.

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Step 4: Verify the Configuration

1. Exit configuration mode:
   Router(config)# exit
Router#
2. Verify the routing table:
   Router# show ip route
   • The primary route (AD=1) will appear in the routing table.
   • The floating static route (AD=10) will not appear unless the primary route fails.
3. Test the primary route:
   Router# ping 192.168.2.1

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Step 5: Simulate a Primary Route Failure

1. Disable the primary route’s interface:
   Router# configure terminal
Router(config)# interface GigabitEthernet0/1
Router(config-if)# shutdown
2. Verify the floating static route becomes active:
   Router# show ip route
   • The floating static route (AD=10) should now appear in the routing table.
3. Test connectivity using the backup route:
   Router# ping 192.168.2.1

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Step 6: Restore the Primary Route

1. Re-enable the primary route’s interface:
   Router(config)# interface GigabitEthernet0/1
Router(config-if)# no shutdown
2. Verify the primary route is restored:
   Router# show ip route
   • The primary route (AD=1) should reappear in the routing table.
   • The floating static route (AD=10) will return to being inactive.

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Step 7: Save the Configuration

To ensure your changes persist after a reboot:

Router# write memory

or

Copy

Router# copy running-config startup-config

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Conclusion

Configuring static routes with administrative distance and floating static routes is a powerful way to create backup paths and ensure network reliability. By assigning a higher AD to a backup route, you can ensure it remains inactive unless the primary route fails. This approach is particularly useful in networks where redundancy and failover are critical.

If you found this guide helpful, feel free to share it with your peers or leave a comment below with your thoughts or questions. Happy networking!

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