Gateway Load Balancer Use Cases

GWLB inserts third-party appliances (firewalls, IDS) inline. The use cases and the alternatives.

When GWLB wins

AWS Gateway Load Balancer (GWLB) is a specialized load balancer designed for transparent, in-path traffic inspection. It is not a general-purpose load balancer; it solves a specific problem: putting third-party network appliances in the traffic path with high availability and horizontal scaling. Most teams will never need it; teams that do need it have few alternatives.

What GWLB is right for:

• Third-party security appliances in the traffic path.: Palo Alto, Fortinet, Check Point, and similar firewall vendors offer GWLB-compatible appliances. The team deploys the appliances behind GWLB; traffic flows through them transparently. The appliances inspect, filter, or transform the traffic.
• Compliance requirements that mandate specific appliance types.: Some compliance regimes specify the use of particular firewall vendors or specific feature sets that AWS-native services do not provide. GWLB lets the team meet these requirements while staying in the cloud.
• Centralized inspection without single points of failure.: Without GWLB, putting appliances in the path required hand-rolled high availability with potential bottlenecks. GWLB provides the load balancing and high availability natively.
• East-west traffic inspection.: Traffic between VPCs (east-west) can be routed through GWLB-fronted inspection. The inspection covers traffic patterns that perimeter-only firewalls miss. Lateral movement detection benefits.
• Internet egress filtering.: Outbound traffic from VPCs can be inspected by GWLB-fronted appliances before reaching the internet. The egress filtering catches data exfiltration, command-and-control beacons, and similar threats.

GWLB is a specialized tool. The use cases are narrow; when they apply, the alternatives are worse.

Alternatives

For most teams, alternatives to GWLB are simpler, cheaper, or both. The right move is usually to consider alternatives first and only adopt GWLB if the alternatives do not fit.

• AWS Network Firewall: managed.: AWS Network Firewall is a managed service that provides similar in-path inspection without the third-party appliance complexity. It is cheaper than GWLB plus appliances; it is operationally simpler. For AWS-native rules, it is often the right choice.
• Cheaper for AWS-native rules.: Network Firewall covers most common security rules: domain blocking, IP blocking, signature-based detection, custom rule sets in Suricata format. The coverage is broad; the cost is moderate.
• Cloudflare for HTTP-layer security.: If the security focus is HTTP-layer (web application firewall, DDoS protection, bot management), Cloudflare or AWS WAF wraps the architecture differently. Traffic enters through the security layer; the inspection is at the application layer rather than the network layer.
• Wraps the architecture differently.: The HTTP-layer pattern routes traffic through the security service before it reaches AWS. The team's AWS-side architecture does not need GWLB; the security is upstream. The pattern is appropriate for public-facing services.
• Per-VPC firewalls and security groups.: Many teams' security needs are met by VPC-level controls: security groups, NACLs, route table discipline. The native controls are cheaper and operationally simpler than introducing GWLB.

Alternatives cover most use cases. GWLB is reserved for cases where the alternatives do not fit.

Design

If GWLB is the right choice, the design pattern is well-established. The team builds a centralized inspection VPC and routes traffic through it via Transit Gateway or VPC peering.

• Centralized inspection VPC.: A dedicated VPC hosts the GWLB and the security appliances. Traffic from other VPCs is routed to this inspection VPC, inspected, and forwarded to its destination. The centralization reduces appliance count and operational burden.
• All traffic flows through.: The routing ensures all traffic that should be inspected actually is. Route tables in spoke VPCs send relevant traffic to the inspection VPC; the inspection cannot be bypassed by misrouting.
• Cost is real.: GWLB has per-endpoint hourly costs and per-GB processing costs. Add the cost of the third-party appliances (often based on throughput or per-instance licensing). The total cost can be significant; high-volume environments see this clearly.
• Weigh against alternatives.: Before committing to GWLB, evaluate alternatives. Is Network Firewall sufficient? Would Cloudflare/WAF cover the use case? Are VPC-level controls enough? The cost-benefit favors alternatives unless GWLB is genuinely required.
• Plan for capacity.: The appliances behind GWLB have throughput limits. Traffic growth requires scaling the appliance fleet; the licensing cost grows with the fleet. Capacity planning is part of the architecture.

Gateway Load Balancer is a specialized tool with a narrow use case. Nova AI Ops integrates with cloud network telemetry, surfaces traffic patterns through inspection paths, and helps teams understand whether the cost of GWLB is producing the security value the team expected.