MTU Mismatch in Overlay Networks
VXLAN's 50-byte overhead means an overlay interface must have an MTU at least that much below the physical path MTU; when it doesn't, small packets flow but large ones are dropped, producing the classic 'handshake succeeds, bulk transfer hangs' failure. The fix is setting com.docker.network.driver.mtu (and verifying path MTU) — a symptom pattern worth recognizing on sight.
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VXLAN's 50-byte overhead means an overlay interface must have an MTU at least that much below the physical path MTU; when it doesn't, small packets flow but large ones are dropped, producing the classic 'handshake succeeds, bulk transfer hangs' failure. The fix is setting com.docker.network.driver.mtu (and verifying path MTU) — a symptom pattern worth recognizing on sight.
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