Network & Infrastructure / Linux Networking & Host Performance
PMTU evidence across namespaces and host forwarding
A workload stalls on large transfers while host-originated tests work. The namespace's route, tunnel path or feedback delivery can differ from the host's own connection.
Environment and inputs: Linux network namespaces, host routing and network drivers; availability and semantics depend on kernel and driver versions. Diagnostic/design example; not tested on production equipment.
Collect the evidence
Capture size feedback at workload, veth and physical boundaries; record namespace routes and applicable firewall policy. Use the workload's actual source address and destination during comparison.
Explain the result
A host test can bypass the forwarding and encapsulation path used by a container. Path-size discovery must reach the endpoint that is transmitting the affected packets.
Plan the fix
Repair feedback delivery or size configuration at the identified boundary and update the provisioning source. Avoid treating a host-level ping as sufficient proof that the workload path is healthy.
Check the result and rollback
Validate large workload transfers on normal and fallback routes, including new containers. Revert if the fix affects host management or leaves another namespace with incompatible packet-size assumptions.