Quality of Service (QoS): Managing Bandwidth More Effectively

Using QoS Classifiers To Configure Quality of Service for Outbound Traffic

Figure 15-18shows an example of the ToS byte in the header for an IP packet, and illustrates the diffserv bits and precedence bits in the ToS byte. (Note that the Precedence bits are a subset of the Differentiated Services bits.)

Field:

Destination

Source MAC

IP Identifier

Type &

ToS Byte

. . .

 

 

MAC Address

Address

 

Version

 

 

 

 

 

 

 

 

 

 

 

Packet:

FF FF FF FF FF FF

08 00 09 00 00 16

08 00

45

E 0

. . .

 

 

 

 

 

 

 

 

 

Differentiated Services Codepoint

Precedence

 

 

 

Not

 

 

Bits

 

 

 

 

Used

 

1

1

 

 

 

 

 

 

1

0

0

0

0

0

 

 

 

 

 

 

 

 

 

 

E

 

 

 

0

 

 

 

 

 

 

 

 

 

Figure 15-18. The ToS Codepoint and Precedence Bits

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