In modern ISP and FTTH networks, uninterrupted internet connectivity is extremely important. Any uplink failure can cause massive customer complaints and service downtime. Failover configuration ensures that when the primary uplink goes down, traffic automatically switches to a backup link without manual intervention. In this guide, you will learn how to configure failover on BDCOM OLT or Switch step by step in a simple and practical way.
What is Failover in ISP Networks?
Failover is a network redundancy mechanism where a secondary (backup) link automatically takes over when the primary link fails. In ISP environments, failover is commonly used between uplink ports, core routers, aggregation switches, and OLT devices. This helps maintain service continuity, minimize downtime, and improve customer satisfaction. Without failover, even a small fiber cut can bring down the entire network.
Why Failover is Important for BDCOM OLT or Switch
BDCOM OLTs and switches are widely used in FTTH networks, and they often handle thousands of subscribers. If the uplink connection fails, all downstream users lose connectivity instantly. Failover allows the OLT or switch to automatically reroute traffic through a backup uplink. This is critical for ISPs who want high availability, reliability, and professional network design.
- Prevents total internet outage
- Ensures automatic recovery during link failure
- Reduces manual intervention and response time
- Improves overall network stability
Step 1: Access BDCOM OLT or Switch CLI
First, you need to access the BDCOM device using CLI mode. You can connect using console cable, Telnet, or SSH depending on your network setup. Use terminal software like PuTTY or SecureCRT and log in with administrator credentials. CLI access is required to apply failover-related configurations properly.
Username: admin Password: ******
Step 2: Identify Primary and Backup Uplink Ports
After logging in, identify which ports are used as uplinks. Typically, SFP or SFP+ ports are used for uplink connections. Decide clearly which port will act as the primary uplink and which one will be used as the backup. This planning step is very important to avoid misconfiguration.
show interface brief
Let’s assume we will include the G1 and G2 ports of our BDCOM OLT or BDCOM Switch under failover configuration. The first thing we need to do is configure a backup-link-group. So, let’s get started.
Step 3: Configure VLAN or Trunk on Uplink Ports
Both primary and backup uplink ports must carry the same VLAN configuration. If VLAN mismatch occurs, failover will not work correctly. Configure both uplinks as trunk ports and allow required service VLANs. This ensures seamless traffic switching during failover.
interface gigabitethernet 0/1 switchport mode trunk exit interface gigabitethernet 0/2 switchport mode trunk exit
Step 4: Configure Backup Link Group
In the case of failover configuration, you need to prepare a backup link group that defines a backup link group (ID: 1). At the same time, it forces the primary link to become active again when it is restored and applies a 3-second delay before switching back to the primary link. I hope you can understand this easily. Please follow the commands below.
backup-link-group 1 preemption-mode forced delay 3
Step 5: Configure Primary & Backup Link or Priority
Failover works based on link status or priority. The primary uplink should have higher priority, while the backup uplink remains on standby. When the primary link goes down, the device automatically activates the backup link. This behavior ensures zero or minimal downtime for subscribers.
Primary Link Active
interface gigabitethernet 0/1 description **Primary-LINK** switchport mode trunk backup-link-group 1 active exit
Backup Link Passive
interface gigabitethernet 0/2 description **Backup-LINK** switchport mode trunk backup-link-group 1 backup exit
Step 6: Test the Failover Configuration
Testing is a critical step and should never be skipped. Disconnect the primary uplink fiber manually and observe traffic behavior. If failover is configured correctly, traffic should instantly move to the backup uplink. Reconnect the primary link to ensure automatic recovery works as expected.
Common Failover Configuration Mistakes
Many failover issues occur due to simple configuration mistakes. VLAN mismatch, incorrect port priority, or disabled monitoring can break failover. Always double-check interface settings and verify both uplinks are operational. Good documentation and labeling help prevent future confusion.
- Different VLANs on primary and backup uplinks
- Wrong port selected as primary
- Failover feature not enabled
- No testing after configuration
Best Practices for ISP Failover Design
For production ISP networks, failover should always be part of the initial design. Use high-quality SFP modules and reliable fiber paths. Whenever possible, route primary and backup links through different physical paths. This reduces the chance of simultaneous failure and improves network reliability.
Conclusion
Failover configuration on BDCOM OLT or Switch is essential for building a stable and professional ISP network. By following this step-by-step guide, you can ensure automatic uplink redundancy and minimal service disruption. A properly configured failover system improves uptime, customer satisfaction, and operational efficiency. Always test and monitor your failover setup to keep your FTTH network running smoothly.
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