> Now, the high boundary seemed reasonable (ETH_FRAME_LEN - ETH_HLEN = > ETH_DATA_LEN) which gives 1500, but why is the low boundary set to 68 ? > According to my calculations, it should have been ETH_ZLEN - ETH_HLEN which > gives 46. The IPv4 minimum MTU is 68 bytes. Below that not all frames can be delivered - : send the line "unsubscribe linux-net" in the body of a message to majordomo@vger.kernel.org