Redundant Last-Mile: Protecting Against Fiber Cuts

Most leased line outages are not caused by equipment failures inside data centres. They are caused by fiber cuts in the last mile — often from road widening, metro construction, utility digging or building renovation. In fast-growing Indian cities, these are frequent.

What path diversity means

A redundant last-mile design brings a second fiber into your building through a different physical route — ideally entering from a different side of the building, travelling down a different street and connecting to a different network node. A single cut then cannot take down both paths.

Diverse vs merely redundant

Two fibers in the same duct are redundant on paper but fail together when that duct is cut. Ask providers to show route maps and confirm physical separation.

Automatic failover

Your router or firewall monitors both links. If the primary fails, traffic moves to the backup within seconds using protocols such as VRRP or BGP. Users usually notice a brief pause at most.

Alternative backup options

• Second leased line from a different provider: maximum independence.
• Business broadband: cost-effective backup for most traffic.
• 4G/5G or wireless links: independent of underground fiber, quick to deploy.

Test failover regularly

Schedule failover tests during quiet hours. Confirm that VPNs, VoIP and critical applications continue working on the backup path.

Consider in-building routes

Within the building, ensure the two fibers use different risers or entry points where possible.

Balance cost and risk

Calculate the cost of an hour of downtime. For many businesses, a few avoided outages pay for redundancy within a year.

The bottom line

If downtime is costly, diverse last-mile is the most effective protection you can buy against the most common cause of outages.

Learn more about Internet Leased Line (ILL) from UbiFi, or talk to our team.