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New Member

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

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

Everyone's tags (3)
8 REPLIES
New Member

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

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

New Member

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

Yes,

it's enabled as well as qos rewrite.

New Member

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

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"?

New Member

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

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#

New Member

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

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

New Member

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

sh mls qos int fast 0/x sta doesn't show any ef. That's why I was puzzled.

I'll try with wireshark to see if it works...

New Member

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

I tried wireshark and it's not showing anything being marked.

another thing is when I do sh policy-map int fast 0/2 lets say, it's not showing any hit.

Hall of Fame Super Bronze

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

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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