Complex sentence: In December 1998, the IETF published RFC 2474 (An Architecture for Differentiated Services) replaced the ToS field with the DiffServ field, in which a range of eight values (class selector) is used for backward compatibility with IP precedence.
Split into simpler sentences: In December 1998, the IETF published RFC 2474 (An Architecture for Differentiated Services), which replaced the ToS field with the DiffServ field. In the DiffServ field, a range of eight values (class selector) is used for backward compatibility with IP precedence.