feat(replication): replace L2 broadcast with UDP unicast - #69
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Two Kind clusters in separate Docker networks connected by a router container with MTU 1500 transit path. Simulates the real-world scenario of ICMP fragmentation-needed generation and go-pmtud UDP replication across L3 boundaries. Includes setup/teardown scripts, DaemonSet manifest, podinfo workload, traffic generation, tcpdump observation helpers, and e2e validation.
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Merging this branch will increase overall coverage
Coverage by fileChanged files (no unit tests)
Please note that the "Total", "Covered", and "Missed" counts above refer to code statements instead of lines of code. The value in brackets refers to the test coverage of that file in the old version of the code. Changed unit test files
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Summary
Eliminates the Layer 2 adjacency requirement for ICMP fragmentation-needed packet replication between Kubernetes cluster nodes. Replaces raw Ethernet frame broadcasting (ARP + MAC resolution) with UDP unicast.
Changes
internal/arp/package, L2 config fields,--iface_names/--iface_mtu/--arp-timeout-seconds/--node-timeout-minutesflagsWriteTo), UDP receiver with TUN device injection,internal/packet/parser--replication-port(default 4390),--ignore-networksflagspmtud0deterministically; iptables NFLOG rule must exclude it (! -i pmtud0)Key Design Decisions
ip_input → icmp_rcv → icmp_unreach) to correctly update PMTU cache! -i pmtud0in iptables rule is the primary mechanism; peer IP filtering +--ignore-networksprovide defense-in-depthRequired iptables rule
Testing
go build ./...✓go test ./...✓go vet ./...✓