How To Set Dscp Values In Linux

Jun 18 2019

How to Gear up the DSCP Flag in Windows and Linux

DSCP (Differentiated Services Code Point) is a series of bits in the IP header for nomenclature purposes. These bits specify the precedence value of the packet, the driblet probability, and the network service used.

Earlier setting the DSCP flag with a desired value, yous need to take some things into consideration. You cannot force the DSCP flag from the Data Distribution Service (DDS) middleware, simply you can advise the system use a specific value. The reason is that all network elements such as switches and routers must have the capability and be enabled to actually employ the TOS bits to treat higher-priority packets differently (TOS is an older mechanism to prioritize packets). In addition, many network transports are not capable of managing packet priority. All this makes it incommunicable for DDS to control the prioritization of data at the network level.

If you desire to advise a DSCP value to your arrangement, you should utilise the transport_priority QoS parameter. Just if you lot desire to alter the metadata packets, you need to use the metatraffic_transport_priority QoS parameter.

Observe that the DSCP can accept different values:

DSCP Value	Decimal Value	Meaning	Drop Probability	Equivalent IP Precedence Value
101 110	46	High Priority Expedited Forwarding (EF)	N/A	101 – Critical
000 000	0	All-time Effort	N/A	000 – Routine
001 010	10	AF11	Low	001 – Priority
001 100	12	AF12	Medium	001 – Priority
001 110	fourteen	AF13	Loftier	001 – Priority
010 010	18	AF21	Low	010 – Immediate
010 100	twenty	AF22	Medium	010 – Immediate
010 110	22	AF23	Loftier	010 – Immediate
011 010	26	AF31	Low	011 – Wink
011 100	28	AF32	Medium	011 – Flash
011 110	thirty	AF33	Loftier	011 – Flash
100 010	34	AF41	Depression	100 – Flash Override
100 100	36	AF42	Medium	100 – Flash Override
100 110	38	AF43	Loftier	100 – Flash Override
001 000	8	CS1		ane
010 000	16	CS2		two
011 000	24	CS3		3
100 000	32	CS4		4
101 000	40	CS5		5
110 000	48	CS6		6
111 000	56	CS7		seven
000 000	0	Default
101 110	46	EF

Linux Systems

If you demand to alter this value on a Linux machine (for user data packets), it would be enough to make the declaration via QoS parameters in your DataWriter:

< transport_priority >

< value > 0x80 </value >

</transport_priority >

And if you want to alter the value of the metadata packets, it should be done by setting the following QoS parameter in your DataWriter:

< metatraffic_transport_priority >

< value > 0x80 </value >

</metatraffic_transport_priority >

Windows Systems

If you demand to change this value on a Windows machine, it won't be enough to make the change in the QoS contour. Instead, it is necessary to do it at the application level and it must exist set past modifying a system registry:

Open the regedit awarding (for case typing regedit in the "Commencement" push button).
Using the left side tree, navigate to HKEY_LOCAL_MACHINE\System\CurrentControlSet\services\Tcpip\Parameters path.
At that place, right click, select "New" and then "DWORD".
Utilise "DisableUserTOSSetting" for the field proper noun and for "0" for the Value data.
Then go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\Tcpip\Qos (if you don't have any QoS in the tree, you can create one with right click>New>Key and enter the QoS name).
Create a string value ( Right click>New>Cord value ) and use "Do not utilize NLA" for the proper name and "i" for the value.
Reboot you computer.
Later your system restarts, open gpedit.msc.
Go to Figurer configuration > Windows Settings > Policy-based QoS and right click on "Create new policy".
Check "Specify DSCP Value" and use the desired value (for instance, 8). Click "Side by side".
Bank check "Only awarding with this executable proper noun:" and fill with Process Name (executable). Click "Next" twice.

After these steps, run your application and the DSCP value should have changed.

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