Designing LTE Backup Internet That Actually Takes Over
A backup circuit that has never been tested is a hope, not a plan. Cellular is an excellent secondary path precisely because it shares no infrastructure with wired service — no shared conduit, no shared central office, no shared last mile. But the cutover mechanics decide whether an outage is a blip or an afternoon.
Detection and cutover
Configure link monitoring against multiple external targets, not just the next-hop gateway — wired service can fail upstream while the local link stays up. Tune detection intervals so brief flaps do not trigger churn, but real outages cut over within seconds.
What survives the switch
Public IPs change on failover, so anything pinned to source addresses — VPN tunnels, allowlisted SaaS, VoIP registrations — must re-establish. Document which sessions self-heal and which need intervention. For critical tunnels, configure both endpoints ahead of time.
Data budget realism
Backup plans with small data buckets die during extended outages. Estimate one business day of real traffic and size the plan accordingly — or configure the failover policy to shed noncritical traffic (backups, media, updates) while on cellular. Need plan guidance? Email sales@rad-nexus.com.
