QoS Classification

Question 1

Class of Service (CoS)

Answer 1

An Ethernet frame marking at layer 2, which contains 3 bits. This is called the Priority Code Point(PCP) within an Ethernet frame header when VLAN tagged frames as defined by IEEE 802.1Q are used.

Question 2

Type of Service (ToS)

Answer 2

ToS comprises of 8 bits, 3 of which are designated as the IP precedence field in an IPv4 packet header. The IPv6 header field is called Traffic Class.

Question 3

Differentiated Services Code Point

DSCP or DiffServ

Answer 3

For classifying and managing network traffic. The technology uses a 6-bit differentiated services code point in the 8-bit Differentiated Services field (DS field) in the IP header for packet classification. DSCP allows for creation of traffic classes that can be used to assign priorities. DSCP is backward compatible with IP precedence.
layer 3 packet markings have end-to-end significance.

Question 4

Class Selector

Answer 4

Class Selector uses the same 3 bits of the field as IP precedence and is used to indicate a 3-bit subset of DSCP values.

Question 5

Traffic Identifier (TID)

Answer 5

used in wireless frames, describe a 3-bit field in the QoS control field in 802.11. TID is for wireless while CoS is for wired.