Networking

Load Balancers: Inline vs One-Arm Topology

Network Design diagram · made in Skemio

Network diagram comparing Inline load balancer acting as default gateway versus One-Arm load balancer attached as a side-arm node with SNAT.
Network diagram comparing Inline load balancer acting as default gateway versus One-Arm load balancer attached as a side-arm node with SNAT.
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What it shows

  • Inline mode sees all traffic naturally but creates a physical bottleneck.
  • One-Arm avoids inline re-cabling but requires SNAT, hiding client IPs.
  • Use X-Forwarded-For headers to preserve real client IPs in One-Arm mode.

The takeaway

Choose One-Arm for plug-and-play simplicity; Inline for preserving IP audit trails.

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