DSCP to DSCP maping

[dayaaalzoubi]

Hi Hatem

What is the use and where to use of DSCP to DSCP maping

Thanks

Dayaa

[Robert Thomas]

Hello Dayaa,

I'm not to sure what you mean by DSCP to DSCP mapping, do you mean matching the traffic by DSCP on the class map and then remarking the traffic in the policy map with a different DSCP value?

[Ganesh Hariharan]

Hi Hatem 
 What is the use and where to use of DSCP to DSCP maping
Thanks
Dayaa 

Hi Dayaa,

I hope you are asking about the DSCP to DSCP mutaution map,If yes then the use for this command in  situations where DSCP is widely used for QOS in all your network devices. If a phone sets DSCP to 46 (Cos 5 or precedence 5)and if you trust COS or IP precedence at the ingress port, the internal DSCP changes to 40. (as per the first picture). To map this value back to 46 before the packet goes out, use the DSCP mutation map.

Or the easy way to set DSCP back to 46 from ingress to egress is,

a. Set ingress trust to Cos or Precedence

b. Use Cos-to-DSCP or Prec-to-DSCP maps to set the internal DSCP as 46 (instead of 40).

c. Do nothing at egress port, the egress DSCP will be set to 46 automatically

Hope to Help !!

Ganesh.H

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