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Cilium L2 Networking Architecture on Talos Linux

Work in Progress

This explanation document is currently under development. Check back soon for a comprehensive deep dive into Cilium L2 networking concepts and architecture.

Planned Content

This page will provide a comprehensive explanation of:

Layer 2 Networking Fundamentals

  • OSI Model Layer 2 - Data Link Layer concepts
  • ARP (Address Resolution Protocol) - How MAC address discovery works
  • Broadcast domains - L2 network boundaries
  • MAC address tables - Switch learning and forwarding

Cilium LB-IPAM Architecture

  • Why Cilium LB-IPAM? - Comparison with MetalLB
  • Integrated vs standalone approach
  • eBPF advantages over traditional implementations
  • Resource efficiency and performance characteristics
  • Operational complexity comparison
  • LB-IPAM components - IP pool management, allocation logic
  • Integration with CNI - How Cilium manages both pod networking and LoadBalancer IPs

L2 Announcement Mechanism

  • Leader election - How Cilium selects which node announces an IP
  • Kubernetes lease-based coordination
  • Failover and high availability
  • Leader re-election scenarios
  • ARP responder - How the leader node responds to ARP requests
  • Gratuitous ARP - Announcing IP ownership on the network
  • Interface selection - Why interface configuration matters

eBPF Packet Processing

  • eBPF programs - How Cilium processes packets in-kernel
  • XDP (eXpress Data Path) - Fast packet processing
  • Connection tracking - Maintaining state for LoadBalancer connections
  • NAT and SNAT - Source address translation behavior

Traffic Policies

  • Cluster policy - Load balancing across all nodes
  • Packet flow diagrams
  • SNAT implications
  • Performance characteristics
  • Local policy - Direct routing to local pods
  • Source IP preservation
  • Health check behavior
  • Potential traffic imbalances

Talos-Specific Considerations

  • KubePrism integration - Why API server access matters
  • CGroup v2 requirements - Modern Linux kernel features
  • Security contexts - Capability restrictions on Talos
  • Interface naming - Network device identification

References


Status: 🚧 Under Construction
Estimated Completion: TBD

For immediate help, refer to the tutorial and how-to guides linked above.