SonicOS 7.1 Objects

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Technical Documentation > SonicOS 7.1 Objects > QoS Marking > 802.1p and DSCP QoS > DSCP Marking

DSCP Marking

Differentiated Services Code Point (DSCP) marking uses 6-bits of the 8-bit ToS field in the IP Header to provide up to 64 classes (or code points) for traffic. Because DSCP is a layer 3 marking method, there is no concern about compatibility as there is with 802.1p marking. Devices that do not support DSCP simply ignores the tags, or at worst, they reset the tag value to 0.

DSCP Marking: IP Packet

DSCP marking:

  • IP packet depicts an IP packet, with a close-up on the ToS portion of the header. The ToS bits were originally used for Precedence and ToS (delay, throughput, reliability, and cost) settings, but were later repurposed by RFC2474 for the more versatile DSCP settings.
  • Commonly used code points shows the commonly used code points, as well as their mapping to the legacy Precedence and ToS settings.
DSCP Marking: Commonly Used Code Points
DSCP DSCP Description Legacy IP Precedence Legacy IP ToS (D, T, R)
0 Best effort 0 (Routine – 000) -
8 Class 1 1 (Priority – 001) -
10 Class 1, gold (AF11) 1 (Priority – 001) T
12 Class 1, silver (AF12) 1 (Priority – 001) D
14 Class 1, bronze (AF13) 1 (Priority – 001) D, T
16 Class 2 2 (Immediate – 010) -
18 Class 2, gold (AF21) 2 (Immediate – 010) T
20 Class 2, silver (AF22) 2 (Immediate – 010) D
22 Class 2, bronze (AF23) 2 (Immediate – 010) D, T
24 Class 3 3 (Flash – 011) -
26 Class 3, gold (AF31) 3 (Flash – 011) T
27 Class 3, silver (AF32) 3 (Flash – 011) D
30 Class 3, bronze (AF33) 3 (Flash – 011) D, T
32 Class 4 4 (Flash Override – 100) -
34 Class 4, gold (AF41) 4 (Flash Override – 100) T
36 Class 4, silver (AF42) 4 (Flash Override – 100) D
38 Class 4, bronze (AF43) 4 (Flash Override – 100) D, T
40 Express forwarding 5 (CRITIC/Elliptic Curve Group – 101) -
46 Expedited forwarding (EF) 5 (CRITIC/Elliptic Curve Group – 101) D, T
48 Control 6 (Internet Control – 110) -
56 Control 7 (Network Control – 111) -

DSCP marking can be performed on traffic to/from any interface and to/from any zone type, without exception. DSCP marking is controlled by Access Rules (Classic Mode) or Security Policies (Policy Mode), from the QoS view, and can be used in conjunction with 802.1p marking, as well as with SonicOS’s internal bandwidth management.

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