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Technical Tip: How to Traffic shape or prioritize locally originating traffic.

Description

This article describes how to traffic shape or prioritize traffic locally originating traffic using ToS or DSCP.

Scope

FortiGate.

Solution

There are two types of traffic mapping: Type of Service (ToS) or DSCP (Differentiated Services Code Point).

Only one method can be used at a time, with ToS set as the default method.

The type used and attributes can be set in the CLI.

To set ToS or DSCP traffic mapping:

config system global

set traffic-priority {tos | dscp} <- Default value TOS.
set traffic-priority-level {low | medium | high} <- Default value High.

end

This means, by default, the local traffic will always have the highest priority.

Mapping of DSCP and ToS hexadecimal values for QoS.

Service Class	DSCP Class	DSCP Bits	DSCP Value	ToS Value	ToS Hexidecimal
Network Control	cs7	111000	56-63	224	0xE0
Internetwork Control	cs6	110000	48-55	192	0xC0
Critical - Voice Data (RTP)	ef	101110	46	184	0xB8
Critical - Voice Data (RTP)	cs5	101000	40	160	0xA0
Flash Override Video Data	af43	100110	38	152	0x98
	af42	100100	36	144	0x90
	af41	100010	34	136	0x88
	cs4	100000	32	128	0x80
Flash Voice Control	af33	011110	30	120	0x78
	af32	011100	28	112	0x70
	af31	011010	26	104	0x68
	cs3	011000	24	96	0x60
Immediate Deterministic (SNA)	af23	010110	22	88	0x58
	af22	010100	20	80	0x50
	af21	010010	18	72	0x48
	cs2	010000	16	64	0x40
Priority Controlled Load	af13	001110	14	56	0x38
	af12	001100	12	48	0x30
	af11	001010	10	40	0x28
	cs1	001000	8	32	0x20
Routine - Penalty Box		000010	2	8	0x08
Routine - Best Effort		000000	0	0	0x00

In earlier versions of FortiOS v6.4, v7.0, and v7.2, the above commands were the only ones that could be used to change traffic priority.

Starting FortiOS v7.4+ supports DSCP and VLAN CoS marking for both local-in and local-out traffic. See the documentation for this.

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