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QoS configuration help

Manish Patel


I am trying to come up with a config for implementing QoS over a 512 kbps WAN link that will traverse voice and data traffic for now.

i am using a cisco 2901 router with 15.1(3)T IOS on it

my config is below

class-map match-any DATA-PRIORITY
match protocol citrix
match protocol ssh
class-map match-any VOICE-CONTROL
match protocol skinny
match protocol mgcp
match protocol h323
class-map match-any VOICE
match protocol rtp audio
class-map match-any ANY
match any

policy-map QOS-POLICY
class VOICE
  priority 188
  set dscp ef
  bandwidth 32
  set dscp af31
  bandwidth 180
  random-detect dscp-based
  set dscp af21
class ANY
  shape average 500000
class class-default
  random-detect dscp-based
  set dscp default
policy-map WAN-QOS-POLICY
class ANY
  shape average 500000
  service-policy QOS-POLICY

interface GigabitEthernet0/1

bandwidth 512

ip address x.x.x.x x.x.x.x

ip pim sparse-dense-mode

service-policy output WAN-QOS-POLICY


when i add in the service-policy output WAN-QOS-POLICY command , i get the error " insufficient bandwidth 256kbps for bandwith guarantee (180)"

if i take out the " bandwidth 512 " command out then i get no issues adding the above command on inteface g0/1

Any help will be great.

thank you

3 Replies 3

Roman Rodichev
Rising star
Rising star

don't use "class ANY" in your WAN-QOS-POLICY policy-map. Use "class class-default" instead.

I would also remove "class ANY" from your child policy

finally, do you need to use NBAR and RTP to match your voice traffic, could you classify basted on TOS markings? If you are working with Cisco IPT, your traffic is automatically marked.

thank you

i shall give that  a go.

I am not sure how to go about using TOS based markings. That knowledge evades me

I was referring to matching your voice traffic on DSCP (TOS = type of service) markings. Most VoIP systems will mark traffic automatically.

Voice should already be marked with EF (match dscp ef) (DSCP decimal 46). Verify this with whatever VoIP system you are using.

Voice control should already be marked with CS3 or AF31 (match dscp cs3, match dscp af31) (DSCP decimal 24 and 26).

Cisco callmanagers and ip phones mark control traffic with CS3. Very old versions marked it with AF31.

Avaya by default might mark it with AF41 (not sure why they still do that!)

Other systems, like Nortel, might have some weird way of *dynamically* marking VoIP traffic. You should verify with the configuration of your VoIP system.

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