DOCSIS Ietf Qos Param Set Tos And Mask

1.3.6.1.2.1.127.1.2.1.17

overwriting IP packet's TOS value. The IP packet TOS byte is bitwise ANDed with docsIetfQosParamSetTosAndMask, and the result is bitwise ORed with docsIetfQosParamSetTosORMask and the result is written to the IP packet TOS byte. A value of 'FF'H for docsIetfQosParamSetTosAndMask and a value of '00'H for docsIetfQosParamSetTosOrMask means that the IP Packet TOS byte is not overwritten. This combination is reported if the referenced parameter is not present in a QOS Parameter Set. The IP TOS octet as originally defined in RFC 791 has been superseded by the 6-bit Differentiated Services Field (DSField, RFC 3260) and the 2-bit Explicit Congestion Notification Field (ECN field, RFC 3168). Network operators SHOULD avoid specifying values of docsIetfQosParamSetTosAndMask and docsIetfQosParamSetTosORMask that would result in the modification of the ECN bits. In particular, operators should not use values of docsIetfQosParamSetTosAndMask that have either of the least-significant two bits set to 0. Similarly, operators should not use values of docsIetfQosParamSetTosORMask that have either of the least-significant two bits set to 1. Even though this object is only enforced by the Cable Modem Termination System (CMTS), Cable Modems MUST report the value as signaled in the referenced parameter.