QoS Int GE for MetroEthernet

Unanswered Question
Sep 8th, 2010

Hi, im trying to aplly QoS for some ip's in my interface GE so they had priority to access the web. But something isnt working right, i think.

Here's the configuration:

Router_Internet_MT#sh policy-map int g0/0.705

  Service-policy output: PARENT

    Class-map: class-default (match-any)
      12337736 packets, 5757875211 bytes
      5 minute offered rate 933000 bps, drop rate 0 bps
      Match: any
      Traffic Shaping
           Target/Average   Byte   Sustain   Excess    Interval  Increment
             Rate           Limit  bits/int  bits/int  (ms)      (bytes) 
        154400000/154400000 965000 3860000   3860000   25        482500 

        Adapt  Queue     Packets   Bytes     Packets   Bytes     Shaping
        Active Depth                         Delayed   Delayed   Active
        -      0         12337736  1462907915 0         0         no

      Service-policy : QoS_Internet

        Class-map: QoS_Web (match-any)
          5951669 packets, 3901172093 bytes
          5 minute offered rate 603000 bps, drop rate 0 bps
          Match: access-group name QoS_Web
            5951669 packets, 3901172093 bytes
            5 minute rate 603000 bps
            Output Queue: Conversation 265
            Bandwidth 25 (%)
            Bandwidth 38600 (kbps) Max Threshold 64 (packets)
            (pkts matched/bytes matched) 0/0
        (depth/total drops/no-buffer drops) 0/0/0

        Class-map: class-default (match-any)
          6386067 packets, 1856703118 bytes
          5 minute offered rate 318000 bps, drop rate 0 bps
          Match: any
Router_Internet_MT#sh run int g0/0.705
Building configuration...

Current configuration : 208 bytes
interface GigabitEthernet0/0.705
bandwidth 40000
encapsulation dot1Q 705
ip address
ip nbar protocol-discovery
no snmp trap link-status
service-policy output PARENT

The problem is that the QoS is calculating the bandwidth not from the ge interface, just from the traffic shaping in the policy-map call parent. I tried to configure the shape average to 100% but it cant be done, i dont know why. In the serial interface i dont have this problem.

If i have to put more info, let me know. Thanks and sorry for my english

I have this problem too.
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Lei Tian Wed, 09/08/2010 - 09:13


Not sure why it doesn't allow you shape to 100%, but since you are going to use the full bandwidth, why don't you apply policy-map under the main interface instead of on sub-interface?


Lei Tian

telecom_minec Wed, 09/08/2010 - 12:10

According to the info that i have, if the conf is in the sub-interface, i have to apply the QoS in that sub-interface. I dont know if its another way to configure QoS to reach what i want. If you are sure that if i apply the service policy in the physical interface, the QoS will work, it would be great.


Lei Tian Wed, 09/08/2010 - 13:11

Say for sure is danger, but I believe you can apply the policy-map on physical interface, so you don't need to have the parent level shaping. QOS might work differently per platform per software version, so it is safer to test it before you put in production.


Lei Tian

telecom_minec Wed, 09/08/2010 - 13:29

Hey, i put the conf on the physical interface (g0/0), and i saw the "tagging" of the packets when i use the "show policy-map int g0/0", as i show below:

Router_Internet_MT#sh policy-map int  g0/0                              

  Service-policy output: QoS_Internet

    Class-map: QoS_Web (match-any)
       49401 packets, 33752923 bytes
       5 minute offered rate 509000 bps, drop rate 0 bps
       Match: access-group name QoS_Web
         49401 packets, 33752923 bytes
         5 minute rate 509000 bps
         Output Queue: Conversation 265
         Bandwidth 25 (%)
         Bandwidth 10000 (kbps) Max Threshold 64 (packets)
         (pkts matched/bytes matched) 0/0
         (depth/total drops/no-buffer drops) 0/0/0

    Class-map: class-default (match-any)
       41778 packets, 6960776 bytes
       5 minute offered rate 123000 bps, drop rate 0 bps
       Match: any

The bandwidth command its working now, its used in the g0/0 like this "badwidth 40000", because i have a 40 Mb ME and im giving 25 % to one web server. Quiestion: How cain i be really sure that the QoS policy im applying its working??

Thanks for answer...

Lei Tian Wed, 09/08/2010 - 18:02


Sorry, I just noticed you are having sub-rate of the interface bandwidth. You will still need a parent level shaper on that case. The reason is without the parent level shaper, the CBWFQ/LLQ will not kick in until interface is congested; the interface doesn't know it can only transmit at 40Mbps, so it will not consider interface congested even transmit rate is way beyond 40Mbps. That will cause CBWFQ/LLQ never kicks in and traffic got dropped at the provider side.

You can still apply the policy-map on physical interface, but you need to use HQOS with parent level shape to 40M. To verify whether the qos is working properly, you can use a traffic generator to send out traffic in different classes, and check queueing behavior with/without congestion. There are also lot qos measurement tools available, but most of them are not free.

Please rate if that helps.


Lei Tian

telecom_minec Thu, 09/09/2010 - 07:01

Hi, i really dont get what you're explaining just above. Do you have a conf example or something that can help me to see the issue better. Thanks for your help......

telecom_minec Thu, 09/09/2010 - 13:38

Im moving this question to Lan Switching and routing, so more people would help me, thanks

Lei Tian Thu, 09/09/2010 - 20:01


The config should similar as what you had before, but instead of applying on sub-interface you can apply it on physical interface.

policy-map CBWFQ                              

class realtime


class signaling



policy-map 40M

class class-default

   shape average 40M

   service-policy CBWFQ

interface GigabitEthernetx

service-policy output 40M

Normally queuing only kicks in on GE interface when the traffic rate exceeds 1000 Mbps. However, you want the queuing kicks in when traffic exceeds 40 Mbps, so traffic will not be dropped at provider side. Therefore, you need to use HQoS. The first level policy shapes all traffic to 40 Mbps rate and attaches the 2nd level policy to the shaper.

Hope that explains better.

Lei Tian

David McDaniel Thu, 09/09/2010 - 22:26

Hi there,

If you have a chance, download a free copy of my company's tool, LiveAction. It can show you how your QoS has been configured, how it is performing, and can help guide you to a proper configuration. Here's a link to the download:


Load the tool, then pull up the QoS interface view of the interface having the problem. That will show you what's configured and how it's performing. In fact, if you'd like, give me a call and I can walk you through it. These types of configurations can be really complicated coming from the CLI only. Let me know if I can be of further assistance.

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David McDaniel

Systems Engineer

ActionPacked! Networks

CCIE #20501

[email protected]

Phone: +1 808-423-1900 x809


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