How to rewrite DSCP value for SIP traffic on 2960 swtch?

Unanswered Question

Hello,


I have been trying to mark SIP with a DSCP value of cs3 without any luck. Hope you can help.


Here's what I've done so far.


access-list 101 permit tcp any any range 5060 5061

access-list 102 permit udp any any range 5060 5061


class-map match-any SIP01

match access-name 101

class-map match-any SIP02

match access-name 102


policy-map MARKSIP

class SIP01

set dscp cs3

class SIP02

set dscp cs3

class class-default

trust dscp


policy is applied to lets say Int Fast 0/24

service-policy input MARKSIP


but the traffic doesn't seem to marked since on the other end of the router, I don't see any incoming cs3 traffic

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c.lemaire Mon, 11/23/2009 - 07:25
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Hi,


Might seem silly but as it is not in your config extract... Did you globally enable QoS with the "mls qos" command?


Hope this help,

Christophe

c.lemaire Mon, 11/23/2009 - 07:46
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Do you have hits on your ACLs?

Could you post the output of "sh mls qos statistics", "sh mls qos interface" and "sh policy-map"?

sure, I use ef instead of cs3 in this configuration just to see if it work: It indicates that I get absolutely 0 hits...

my pc is plugged in port fast 0/2, the SIP running application is running on my pc. I also went as far as even try to tag http traffics without luck.



CBCI_Lachine#sh class-map
Class Map match-any class-default (id 0)
   Match any


Class Map match-any 101 (id 1)
   Match access-group  101


Class Map match-any 103 (id 3)
   Match access-group  103


Class Map match-any 102 (id 2)
   Match access-group  102


Class Map match-any 104 (id 4)
   Match access-group  104


CBCI_Lachine#sh access-list
Extended IP access list 101
    10 permit tcp any any range 5060 5061
Extended IP access list 102
    10 permit tcp any range 5060 5061 any
Extended IP access list 103
    10 permit udp any range 21000 21900 any range 50000 52399
Extended IP access list 104
    10 permit udp any range 50000 52399 any range 21000 21900
CBCI_Lachine#sh policy-map
  Policy Map marksip
    Class 101
      set dscp ef
    Class 102
      set dscp ef
    Class 103
      set dscp ef
    Class 104
      set dscp ef
    Class class-default
      trust dscp



CBCI_Lachine#sh mls qos int fast 0/2
FastEthernet0/2
Attached policy-map for Ingress: marksip
trust state: not trusted
trust mode: not trusted
trust enabled flag: ena
COS override: dis
default COS: 0
DSCP Mutation Map: Default DSCP Mutation Map
Trust device: none
qos mode: port-based


CBCI_Lachine#sh policy-map int fast 0/2
FastEthernet0/2


  Service-policy input: marksip


    Class-map: 101 (match-any)
      0 packets, 0 bytes
      5 minute offered rate 0 bps, drop rate 0 bps
      Match: access-group 101
        0 packets, 0 bytes
        5 minute rate 0 bps


    Class-map: 102 (match-any)
      0 packets, 0 bytes
      5 minute offered rate 0 bps, drop rate 0 bps
      Match: access-group 102
        0 packets, 0 bytes
        5 minute rate 0 bps


    Class-map: 103 (match-any)
      0 packets, 0 bytes
      5 minute offered rate 0 bps, drop rate 0 bps
      Match: access-group 103
        0 packets, 0 bytes
        5 minute rate 0 bps


    Class-map: 104 (match-any)
      0 packets, 0 bytes
      5 minute offered rate 0 bps, drop rate 0 bps
      Match: access-group 104
        0 packets, 0 bytes
        5 minute rate 0 bps


    Class-map: class-default (match-any)
      0 packets, 0 bytes
      5 minute offered rate 0 bps, drop rate 0 bps
      Match: any
        0 packets, 0 bytes
        5 minute rate 0 bps


CBCI_Lachine#sh mls qos int fast 0/2 stat
FastEthernet0/2


  dscp: incoming
-------------------------------


  0 -  4 :      473660            0            0            0            0
  5 -  9 :           0            0            0            0            0
10 - 14 :           0            0            0            0            0
15 - 19 :           0            0            0            0            0
20 - 24 :           0            0            0            0            0
25 - 29 :           0            0            0            0            0
30 - 34 :           0            0            0            0            0
35 - 39 :           0            0            0            0            0
40 - 44 :           0            0            0            0            0
45 - 49 :           0            0            0            0            0
50 - 54 :           0            0            0            0            0
55 - 59 :           0            0            0            0            0
60 - 64 :           0            0            0            0
  dscp: outgoing
-------------------------------


  0 -  4 :      360630            0            0            0            0
  5 -  9 :           0            0            0            0            0
10 - 14 :           0            0            0            0            0
15 - 19 :           0            0            0            0            0
20 - 24 :           0            0            0            0       479327
25 - 29 :           0            0            0            0            0
30 - 34 :           0            0            0            0            0
35 - 39 :           0            0            0            0            0
40 - 44 :           0            0            0            0            0
45 - 49 :           0            0            0         6950            0
50 - 54 :           0            0            0            0            0
55 - 59 :           0            0            0            0            0
60 - 64 :           0            0            0            0
  cos: incoming
-------------------------------


  0 -  4 :      475627            0            0            0            0
  5 -  7 :           0            0            0
  cos: outgoing
-------------------------------


  0 -  4 :      422990            0            0       479327            0
  5 -  7 :           0         6950          116
Policer: Inprofile:            0 OutofProfile:            0


CBCI_Lachine#

c.lemaire Mon, 11/23/2009 - 23:48
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The config looks good for me. I remember I've had same kind of issue with the counters on a 3750. Could you check the command "sh mls qos int fast 0/x stat" for the outgoing interface? You should see outgoing dscp with ef value.   An other thing you could try is to take a capture with wireshark...  Christophe

Edison Ortiz Thu, 11/26/2009 - 10:11
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Make sure to modify the default dscp-cos maps with the following command:


mls qos map cos-dscp 0 8 16 24 32 46 48 56

You won't see any incoming markings with the mls qos commands as mentioned on this thread as you are marking the packets as they enter the switch.

For those mls qos commands to show the counter, the packets must be marked by the device before they enter the switch.


To see if those TOS markings are being preserved as they exit the switch, you need to execute the mls qos interface command on the egress switchport towards the router AND you must make sure to have 'mls qos trust dscp' enabled on that switchport. If you have it disabled, the TOS marking will not be preserved.


Regards


Edison

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