Why Network Sizing Must Account for the Firewall Chokepoint
A common operational bottleneck during network upgrades is sizing the fiber circuit in isolation from customer premises equipment (CPE). Deploying a 1Gbps symmetric leased line will not deliver gigabit speeds if the perimeter firewall cannot decrypt and inspect traffic at line rate.
When sizing an enterprise deployment, our network engineers evaluate four concurrent constraints:
- Symmetric Upstream Capacity (1:1 Ratio): Unlike commercial broadband (FTTP), where upload speeds are capped at a fraction of download speed, an enterprise leased line delivers identical throughput in both directions. In modern offices running simultaneous Microsoft Teams video meetings, off-site NAS backups, and cloud CRM updates, upload bandwidth is invariably the first pipe to saturate.
- Deep SSL/TLS 1.3 Inspection Overhead: Over 85% of corporate web traffic is encrypted. If your organisation requires deep threat protection, antivirus scanning, and application control, the firewall must decrypt packets in real time. Without dedicated hardware ASIC acceleration, firewall CPU load spikes, throttling a 1Gbps bearer down to 200–300Mbps.
- Stateless Routing vs. Deep Inspection: If your priority is unmetered throughput and wire-speed routing without recurring subscription overhead, dedicated multi-core Layer 3 routing appliances deliver exceptional packet-per-second performance. Read our engineering review on MikroTik in the Enterprise for full protocol analysis.
- Contention & SLA Guarantees: Shared broadband contends traffic among up to 32 premises. Dedicated leased lines provide an uncontended 1:1 optical path backed by a contractually binding 4-hour on-site fix SLA. Explore our detailed breakdown in DIA vs Business FTTP.
Committed Speed vs. Physical Bearer Size
Enterprise circuits are delivered in two components: the physical bearer and the committed port speed.
For example, ordering 200Mbps on a 1Gbps bearer provisions a full 1,000Mbps fiber optic cable into your comms cabinet, but bills for 200Mbps. If your organisation expands or adds staff next quarter, our Network Operations Centre can scale your committed bandwidth to 500Mbps or 1,000Mbps remotely within hours—without civils, road closures, or new hardware.
When to Deploy Diverse Dual Routing (RO2) Active-Passive Failover
For offices with more than 50 staff, or operations where hourly downtime causes substantial financial loss, relying on a single physical cable leaves operations exposed to accidental street roadworks.
Deploying Resilient Option 2 (RO2) active-passive failover provides:
- Two physically separate fiber entries into your premises from opposite building aspects.
- Circuits terminating at completely independent telephone exchanges.
- Automated sub-second failover orchestrated through our managed SD-WAN layer to preserve active sessions without dropped calls. Compare architectures in our guide to SD-WAN vs Leased Lines.