Load Balancing Internet Access: A Business Resilience Guide

What Is Internet Load Balancing?

Load balancing, in the context of internet access, is the practice of distributing network traffic across two or more physical connections simultaneously. Rather than using one connection for everything and switching to a second only when the first fails, a load balancer actively uses both circuits in parallel — sending different traffic flows across different links at the same time.

The result is better utilisation of available bandwidth and improved resilience. If one circuit degrades or drops entirely, the load balancer detects this automatically and redirects all traffic to the remaining connection — without any intervention from your IT team and, in most cases, without visible disruption to users.

Load Balancing vs Failover

These two terms are often confused but refer to meaningfully different configurations:

• Failover: One connection is primary; a second sits idle as a backup. Traffic switches to the backup only when the primary fails. The backup circuit's capacity is wasted under normal conditions.
• Load balancing: Both connections are active simultaneously. Traffic is distributed across both links. If one fails, the other absorbs all traffic.

For most businesses, load balancing is the more efficient configuration — you are paying for both circuits regardless, so distributing traffic across them makes full use of available capacity. Failover is appropriate where one of the circuits is a low-cost 4G/5G link that would be expensive to use for primary traffic but provides adequate backup cover.

How Load Balancing Works

Load balancing is typically performed by a router or firewall that supports multiple WAN interfaces. The device monitors both connections in real time, measuring throughput, latency and packet loss on each. It then applies a distribution policy — either weighted (directing proportionally more traffic to the faster link) or equal (splitting traffic 50/50 regardless of circuit speed).

Modern load balancers can operate at a per-session level (routing each new connection to whichever link is best at that moment) or a per-packet level (splitting individual data flows across multiple paths). Per-session balancing is simpler and avoids packet reordering issues; per-packet offers finer control but requires more sophisticated hardware.

Common Use Cases

• Combining FTTC and 4G/5G: A popular choice for smaller offices — a fixed broadband line carries most traffic while a 4G router provides both additional capacity and failover
• Dual FTTP: Two full fibre connections from different providers delivering combined throughput with carrier-level redundancy
• FTTP plus leased line: A leased line for business-critical traffic and VoIP; FTTP for general browsing and downloads
• Multi-site organisations: Each office site runs dual-connection load balancing to ensure branch resilience

What Hardware Do You Need?

Load balancing requires a router with multi-WAN capability. Common options in UK business deployments include:

• Draytek Vigor: Popular SME router with robust dual-WAN load balancing. Typically £200-£600 depending on model.
• Fortinet FortiGate: Enterprise-grade firewall with SD-WAN and load balancing built in. More appropriate for mid-market and above.
• Peplink Balance: Specialist multi-WAN router designed specifically for load balancing and bonding scenarios.
• Cisco Meraki: Cloud-managed SD-WAN with auto-VPN and dual-WAN failover.

For businesses that want the resilience benefits without managing the hardware themselves, SD-WAN as a managed service achieves the same outcome with a single monthly fee covering both the equipment and the configuration.

Load Balancing vs Network Bonding

Network bonding goes a step further than load balancing. Rather than distributing separate traffic sessions across multiple links, bonding combines two or more connections into a single logical circuit — meaning a single large file transfer or video call can use the combined bandwidth of both lines simultaneously. This requires specialist hardware at both ends of the connection (typically a bonding device at your premises and a concentrator at the supplier's data centre). Load balancing is simpler and does not require infrastructure at the provider end.

Is Load Balancing Right for Your Business?

Load balancing makes most sense for businesses where internet downtime would cause meaningful disruption but where the full cost of a leased line — typically from £199/month — is difficult to justify. A combination of FTTC or FTTP as the primary circuit plus a 4G/5G router as secondary can be achieved for under £100/month total, delivering meaningful resilience at a fraction of the leased line cost.

For organisations where internet availability is truly business-critical — financial services, healthcare, call centres, e-commerce — a leased line with a formal SLA remains the more appropriate solution.