Post

Comparing GCP and AWS Application Load Balancers

Posted
By HTET HTET MIN
views 3 min read
Comparing GCP and AWS Application Load Balancers

In modern distributed architectures, load balancing is not just a mechanism for spreading traffic. It is a foundational control plane that impacts latency, reliability, multi-region strategy, and even compliance. Two of the most widely used cloud platforms—AWS and GCP—both offer Application Load Balancers (ALBs), but their approaches differ in scope, functionality, and global reach.

This post highlights the architectural differences between AWS and GCP Application Load Balancers, with a focus on real-world implications for senior engineers and architects.

1. Scope and Regionality

  • AWS Application Load Balancer (ALB)
    • Regional construct: an ALB lives entirely within a single AWS Region.
    • Can span multiple Availability Zones (AZs) within that region.
    • Does not natively support cross-region load balancing.
    • To achieve global distribution, AWS customers layer services like Route 53 (DNS-based) or Global Accelerator (Anycast IPs with routing policies).
  • GCP External Application Load Balancer (Global HTTP(S))
    • Global construct: a single Anycast IP serves as the entry point worldwide.
    • Native cross-region support: traffic is automatically directed to the closest healthy backend across regions.
    • Simplifies deployment—no need to stitch DNS policies or external accelerators.

Takeaway: AWS ALB is region-bound; GCP’s external ALB is inherently global.

2. Traffic Management and Protocol Support

  • AWS ALB
    • L7 load balancing with support for HTTP, HTTPS, and WebSocket.
    • Advanced routing features: host/path-based routing, query string/method headers, weighted target groups.
    • Tight integration with AWS services (e.g., Lambda as a backend target, WAF, Cognito authentication).
  • GCP Application Load Balancer
    • Also operates at L7 with HTTP, HTTPS, and gRPC support.
    • Provides URL maps for sophisticated routing (host/path-based).
    • Global routing decisions leverage Google’s backbone to minimize latency.
    • Integrates with Cloud Armor (WAF), Identity-Aware Proxy, and Cloud CDN.

Takeaway: Both platforms offer robust L7 routing, but GCP embeds latency-aware global routing as a first-class feature.

3. Cross-Region & Multi-Cloud Strategy

  • AWS
    • Requires additional services (Route 53, Global Accelerator, or CloudFront) for multi-region HA/DR scenarios.
    • Operational overhead: architects must design failover policies, health checks, and DNS propagation strategies.
    • More composable, but with added complexity.
  • GCP
    • Cross-region support is native, reducing architectural complexity.
    • Failover is automatic within the load balancer layer.
    • Better suited for organizations seeking simplified global deployments without custom DNS routing.

4. Internal Load Balancing

  • AWS
    • Offers internal ALBs and NLBs scoped to a VPC within a region.
    • Cross-region internal load balancing is not supported.
  • GCP
    • Provides Cross-Region Internal Application Load Balancer, a global internal L7 load balancer.
    • Allows private workloads to leverage Google’s backbone for cross-region HA.
    • Distinct advantage for multi-region service meshes and hybrid workloads.

5. Pricing and Cost Predictability

  • AWS ALB
    • Pricing model: per-hour charge + per-LCU (Load Balancer Capacity Unit).
    • LCU captures new connections, active connections, rule evaluations, and data processed.
    • Cost scales with complexity of traffic patterns, not just bandwidth.
  • GCP ALB
    • Pricing model: global forwarding rules + backend service charges + bandwidth.
    • Generally simpler to estimate when workloads are global, though regional cost optimizations may be less granular.

6. Strategic Considerations

  • AWS ALB excels when:
    • You operate primarily within a single AWS Region.
    • You need deep integration with AWS ecosystem features (Lambda, ECS, Cognito).
    • You value modularity and are comfortable managing DNS-based global distribution.
  • GCP ALB excels when:
    • You need built-in global distribution with Anycast IPs.
    • You want to reduce operational overhead for multi-region HA.
    • You plan to integrate with Google’s CDN, Cloud Armor, or hybrid networking.

Final Thoughts

Both AWS and GCP offer world-class L7 load balancing, but their philosophies diverge:

  • AWS takes a modular approach: ALB for regional L7, Route 53 or Global Accelerator for global traffic distribution.
  • GCP takes a converged approach: a single load balancer resource can span the globe.

For architects, the decision often comes down to whether you prefer fine-grained control with composable services (AWS) or simplified global reach with fewer moving parts (GCP).

Let me know your thoughts or experiences with AWS and GCP load balancers—I’d love to hear how you approach multi-region architectures.

cloud, load-balancing, aws, gcp, architecture
load-balancing aws gcp architecture application-load-balancer
This post is licensed under CC BY 4.0 by the author.