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DSCP mutation map

asit1111990
Level 1
Level 1

Hello Friends,

 

I was studying QOS and came across concept of dscp mutation map. I have serached my topics and still not cleat what is a dscp mutation map and how to be read its matrix .

It would be great if someone could explain it

 

Thank you!

 

2 Replies 2

Hello


@asit1111990 wrote:

Hello Friends,

l not cleat what is a dscp mutation map and how to be read its matrix .

It would be great if someone could explain it


When you enable Qos on a switch -  DCSP re-write is also enabled

as such any dscp marked traffic coming into the switch it will be over wrote to the default DSCP re-write value 0

Switch#sh mls qos
QoS is disabled
QoS ip packet dscp rewrite is enabled  < Only applicable when QOS is enabled)

Switch(config)#mls qos
Switch#sh mls qos
QoS is enabled
QoS ip packet dscp rewrite is enabled


 

So to negate this you can create a DSCP mutation class to change this behavior:

DSCP mutation example
:
sh mls qos maps dscp-mutation
   Dscp-dscp mutation map:
   Default DSCP Mutation Map:
     d1 :  d2 0  1  2  3  4  5  6  7  8  9
     ---------------------------------------
      0 :    00 01 02 03 04 05 06 07 08 09
      1 :    10 11 12 13 14 15 16 17 18 19
      2 :    20 21 22 23 24 25 26 27 28 29
      3 :    30 31 32 33 34 35 36 37 38 39
      4 :    40 41 42 43 44 45 46 47 48 49
      5 :    50 51 52 53 54 55 56 57 58 59

      6 :    60 61 62 63

 

conf t
mls qos map  dscp-mutation STAN 1 to 50

int x/x
mls qos dscp-mutation STAN
mls qos trust dscp

 

sh mls qos maps dscp-mutation STAN
DSCP Mutation Map: STAN

sh mls qos maps dscp-mutation STAN
   Dscp-dscp mutation map:
   STAN:
     d1 :  d2 0  1  2  3  4  5  6  7  8  9
     ---------------------------------------
      0 :    00 50 02 03 04 05 06 07 08 09
      1 :    10 11 12 13 14 15 16 17 18 19
      2 :    20 21 22 23 24 25 26 27 28 29
      3 :    30 31 32 33 34 35 36 37 38 39
      4 :    40 41 42 43 44 45 46 47 48 49
      5 :    50 51 52 53 54 55 56 57 58 59
      6 :    60 61 62 63

 

sh mls qos int x/x | in DSCP|dscp
trust state: trust dscp
trust mode: trust dscp
DSCP Mutation Map: STAN

So now any marked DSCP value of 1 incoming into this interface when QOS is enabled will be re-wrote to DSCP 50

res

Paul


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Kind Regards
Paul

nicely illustrated with the example.

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