The RFC 2698 says - "The color is coded in the DS field [RFC2474] of the packet in a PHB specific manner". I am trying to understand how color is encoded like in the IPv4 header - in the TOS field where the color information is encoded. Also, how it knows it is green, yellow or red?
In case, QoS is used for L2 i.e 802.1Q - PCP - Priority Code point, where the color is encoded here.