📘 CCNA 200-301 v1.1
3.3 Configure and verify IPv4 and IPv6 static routing
3.3.d Floating Static Routes
1. What is a Floating Static Route?
A floating static route is a backup static route that only becomes active when the primary route fails.
It’s called “floating” because it “floats” below the main route in the routing table — it stays inactive until it’s needed.
In simple words:
- You create two routes to the same destination.
- One is the main (primary) route.
- The other is the backup (floating) route.
- The backup route activates automatically if the main route becomes unavailable.
2. Why do we need Floating Static Routes?
In a real IT environment, network devices like routers often have multiple connections (for example, one to the main ISP and another to a backup ISP).
If the main ISP link fails, you don’t want the network to stop working.
A floating static route makes sure traffic can still reach its destination by using the backup link automatically.
This is useful in:
- WAN redundancy
- Branch office to HQ backup paths
- Failover setups
3. How does a Floating Static Route work?
Routers choose the best route using something called Administrative Distance (AD).
Administrative Distance (AD) is the measure of trustworthiness of a route.
The lower the AD, the more preferred the route.
For static routes:
- A regular static route has an AD of 1 (very trusted).
- A floating static route has a higher AD (example: 10, 20, 200, etc.).
Because it has a higher AD, it will not be used as long as a route with a lower AD (like a primary static or dynamic route) is available.
When the primary route fails, it disappears from the routing table.
Then the floating static route “floats up” and becomes active.
When the primary route comes back, the router automatically switches back to it because it has a lower AD.
4. Floating Static Route Configuration (IPv4)
Syntax:
ip route <destination_network> <subnet_mask> <next_hop_IP> [administrative_distance]
Example:
Suppose:
- Main route to network 10.10.10.0/24 goes through 192.168.1.1
- Backup route goes through 192.168.2.1
R1(config)# ip route 10.10.10.0 255.255.255.0 192.168.1.1
R1(config)# ip route 10.10.10.0 255.255.255.0 192.168.2.1 5
✅ Explanation:
- The first route (AD = 1 by default) is the primary route.
- The second route (AD = 5) is the floating route.
- Router will use the first route as long as it works.
- If 192.168.1.1 becomes unreachable, the router will use 192.168.2.1.
5. Floating Static Route Configuration (IPv6)
Syntax:
ipv6 route <destination_network/prefix> <next_hop_IP> [administrative_distance]
Example:
Suppose:
- Main route to 2001:db8:10::/64 goes through 2001:db8:1::1
- Backup route goes through 2001:db8:2::1
R1(config)# ipv6 route 2001:db8:10::/64 2001:db8:1::1
R1(config)# ipv6 route 2001:db8:10::/64 2001:db8:2::1 10
✅ Explanation:
- The first route (AD = 1 by default) is primary.
- The second route (AD = 10) is floating.
- If the first next-hop becomes unreachable, the router will use the second one.
6. Verifying Floating Static Routes
Use the following commands to check the routes and behavior:
1️⃣ show ip route
Shows which route is currently active.
2️⃣ show running-config | include ip route
Displays all static route configurations.
3️⃣ ping or traceroute
Used to test connectivity and verify route failover behavior.
4️⃣ show ipv6 route
For IPv6 routes.
7. Example Scenario (IT-based)
In a company network:
- The router connects to the main data center via a leased line.
- There’s also a VPN tunnel over the internet as a backup path.
If the leased line (main route) goes down, the floating static route automatically sends traffic through the VPN tunnel until the main link is restored.
This ensures network uptime and business continuity, without any manual changes.
8. Important Points for the CCNA Exam
| Concept | Description |
|---|---|
| Purpose | To provide a backup route in case the primary route fails |
| Default AD for static route | 1 |
| Floating static AD | Must be higher than 1 |
| Activation | Only active when no lower AD route exists |
| Deactivation | Automatically removed when primary route returns |
| Used with | Both IPv4 and IPv6 |
| Verification commands | show ip route, show ipv6 route, show running-config |
9. Common Mistakes to Avoid
| Mistake | Why it’s wrong |
|---|---|
| Not setting higher AD | The router will treat both routes as equal and may load-balance instead of using one as backup. |
| Using incorrect next-hop or interface | The backup route may never activate correctly. |
| Forgetting to test failover | Always simulate link failure (like shutting down interface) to verify backup activation. |
✅ Summary
| Term | Meaning |
|---|---|
| Floating Static Route | A backup static route that activates when the primary route fails |
| Administrative Distance | Value used to choose the most preferred route |
| Higher AD | Less preferred (used as backup) |
| Active when | Primary route is unavailable |
| Supported on | Both IPv4 and IPv6 |
In short:
A floating static route is a reliable backup mechanism that helps maintain network connectivity when the main route fails. It’s configured using a higher administrative distance, and it’s a crucial part of the CCNA 200-301 routing fundamentals.
