https://cfp.cloud-native.rejekts.io/cloud-native-rejekts-europe-london-2025/talk/UFZNVH/ Load Balancing is a critical aspect of modern cloud deployments, and it’s especially tricky and misunderstood in hybrid environments that span across public clouds and private datacenters on premise. Designing a future-proof solution that is scalable, robust, fast and includes automatic failovers for different disaster cases, is a challenge we need to tackle. Therefore, our evaluation focused on two base technologies: Multi-Cluster Meshes and DNS based Global Load Balancing. Join us on our journey of evaluating the two CNCF projects Cilium and K8GB against real-world scenarios with complex multi-cloud deployments. Learn about the benefits, challenges and trade-offs you should expect when choosing a hybrid cloud strategy with Kubernetes! A practical live demo will share our hands-on experience, pros and cons, alongside use-case-specific solution recommendations for your hybrid-cloud journey.

1. Evaluating
Global Load
Balancing
Options for Kubernetes in Practice

2. Nicolai Ort
Cloud Platform Engineer
DATEV
Tobias Schneck
Principal Architect
Kubermatic
@toschneck
@nicolaiort

3. Load
balancing
The Basics

4. Load balancing

5. Load balancing 101

6. Load balancing
…but Kubernetes

7. Load balancing
…but Kubernetes
…and external LB

8. Load balancing 101
● Distribute incoming network traffic across multiple backend
● Preventing Overload of backends
● Health checks to avoid faulty backends
● Precondition for:
○ Delivering high availability services
○ Zero downtime Deployments
● Security Layer
○ Protect Backends
○ Surrounded with Firewalls and WAFs
BUT …. Also single point of failure!

9. Load balancing 101
North-South
East-West
Client
Internet
Data Center
Compound K8s
Clusters
Switches
Firewall - Central
LB

10. Isnʼt this enough?

11. When do you need it?

12. Cluster Mesh
Case 1

13. ● Enable pod-to-pod connectivity across all clusters
● Define global services to load-balance between clusters
● ❗Needs direct Node-to-Node Layer 4 connectivity + non overlapping Node IPs
Cluster Mesh Architecture

14. Cluster Mesh Architecture in Detail
● Cluster Mesh API Server
○ Is read-only and is used by the remote nodes to get the local cluster status
○ Can be exposed via NodePort or LoadBalancer service

15. Environment
github.com/nicolaiort/rejekts2025-glsb

16. Cluster Mesh Bootstrapping

17. Cluster Mesh Bootstrapping

18. Cluster Mesh Bootstrapping

19. Cluster Mesh Bootstrapping

20. Cluster Mesh Bootstrapping

21. Cluster Mesh Bootstrapping

22. Cluster Mesh Bootstrapping

23. Environment
Cluster Mesh Bootstrapping

24. Cluster Mesh Bootstrapping

25. Environment
Cluster Mesh Bootstrapping

26. Cluster Mesh Bootstrapping

27. Routing Strategies

28. Use Case: DC or Cluster fail out

29. Use Case: DC or Cluster fail out

30. Use Case: DC or Cluster fail out

31. Use Case: DC or Cluster fail out
Only works as long as Cluster 2 is functional!

32. Global Service
Load Balancing
Move across the world

33. Global load balancing

34. Just buy it

35. But how?

36. DNS- A quick reminder

37. DNS - A large system

38. But how does DNS help us?

39. K8GB
The kubernetes-native GSLB

40. K8GB: How it helps us

41. K8GB: On our clusters

42. K8GB: With the upstream

43. K8GB: Another DNS-Layer

44. K8GB: They talk to each other

45. K8GB: Add the user

48. Lessons
learned
How did they compare?

49. Comparison ⚔
Cluster Mesh
✅ Fine-grained control traffic management
✅ mTLS option for inner cluster communication
⏺ Pod-to-Pod communication
⏺ Observability of data flows
❌ Direct node-2-node communication required
❌ Full cluster outage not supported
❌ Troubleshooting of Sidecars / Mesh complexity
❌ Difficult to automate Setup (TLS handshake)
✅ DNS: simple bulletproofed core web technology
✅ On-failure: manual management possible
✅ No direct node-2-node network opening
✅ Global scalability & geo aware routing
✅ Fully automated cluster failover
⏺ Hosting own sub DNS zone
❌ DNS TTL caching
❌ No cluster-2-cluster traffic management
Global Load Balancer

50. Clustermesh and dns can be combined

51. Next steps
Schedule across clusters
Karmada
Liqo
Admirality
Armada
Kubeadmiral

52. Thanks
100%
Slides and code will be available after the talk.

53. Links,sources and other stuff
- Demo code and images: https://github.com/nicolaiort/rejekts2025-glsb
- Slides styles, credits to Mario Fahlandt
- Demoed tools
- K8GB: https://www.k8gb.io/
- Cilium: https://cilium.io/
- Illustration tools:
- Drawings: https://excalidraw.com/
- Diagramms: https://mermaid.org

54. Links,sources and other stuff
- Multi-Cluster scheduling
- https://karmada.io/
- https://armadaproject.io/
- https://kubeadmiral.io/
- https://admiralty.io/
- https://liqo.io/
-