Re: Puzzling QoS Issue

Joseph,

If it was a carrier shaping/policing issue though, why does removing
the shaper on my end resolve the issue

Sent from my iPad

On Apr 19, 2013, at 9:20 PM, "Joseph L. Brunner"
<joe_at_affirmedsystems.com> wrote:

> Your carrier has a aggregate shaper applied or some other type of qos mechanism applied.
>
> You're maxing it pal.
>
> They probably did the wrong "BE" setting, etc.
>
> :)
>
> -----Original Message-----
> From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of Tony Singh
> Sent: Friday, April 19, 2013 8:32 PM
> To: Joe Astorino
> Cc: Matt Bentley; Groupstudy
> Subject: Re: Puzzling QoS Issue
>
> yeh without further tests it's hard to say what the issue is, what's the uptime? is the code/license identical to your other working router ;)
>
> --
> BR
>
> Tony
>
> Sent from my iPhone on 3
>
> On 20 Apr 2013, at 00:50, Joe Astorino <joeastorino1982_at_gmail.com> wrote:
>
>> CPU and memory seem to be OK. sh proc cpu shows it sitting about
>> 7-10% when
> the problem occurs. sh proc cpu history does not show any really bad spikes.
> sho proc mem seems to show I have plenty of free RAM as well.
>>
>>
>> On Fri, Apr 19, 2013 at 7:43 PM, Joe Astorino
>> <joeastorino1982_at_gmail.com>
> wrote:
>> Sorry, 2GB of RAM is what it has
>>
>>
>> On Fri, Apr 19, 2013 at 7:41 PM, Matt Bentley <mattdbentley_at_gmail.com>
> wrote:
>> Interesting. I've done testing with Spirent and other traffic-gen
> platforms. I never saw shaping add to the latency - until I actually got up close to the CIR - maybe slightly with a lower-end platform. But I don't think shaping even activates until it senses backpressure and activates "itself".
>>
>>
>> On Fri, Apr 19, 2013 at 4:17 PM, Tony Singh <mothafungla_at_gmail.com> wrote:
>> The reason why you get the extra delay when the policy is applied is
>> down to
> the extra work the CPU has to do on top of inbound congestion, what's your memory/free?
>>
>> I would also raise a TAC to get the definitive answer "show
>> tech-support" &
> pass to them
>>
>> --
>> BR
>>
>> Sent from my iPhone on 3
>>
>> On 19 Apr 2013, at 23:13, Joe Astorino <joeastorino1982_at_gmail.com> wrote:
>>
>>> Another interesting fact - When the policy is applied as shown
>>> above, the problem only occurs when the inbound RX is congested.
>>>
>>> So basically, if the service-policy is applied outbound towards the
>>> WAN
> as
>>> shown, and the output utilization of the WAN link (TX) is low, and
>>> the inbound (RX) utilization is low, everything is fine.
>>>
>>> In the event that the inbound utilization of the interface (RX) is
>>> significant, and the policy is applied outbound as usual, the policy
>>> is adding the 200-400ms extra delay. If I remove the policy, the
>>> extra delay goes away.
>>>
>>> I guess I don't understand why inbound congestion would change how
>>> the outbound queue / shaping works.
>>>
>>> input is low, output is low, policy applied: fine input is high,
>>> output is low, policy not applied: expected poor response times
>>> input is high, output is low, policy is applied: expected poor
>>> response time PLUS an additional 200-400ms of delay
>>>
>>>
>>> On Fri, Apr 19, 2013 at 5:49 PM, Joe Astorino
> <joeastorino1982_at_gmail.com>wrote:
>>>
>>>> I have a 3945 ISR router connected via a GigabitEthernet link to a
> service
>>>> provider that is providing 10Mbps WAN access. I wish to use CBWFQ
>>>> and
> the
>>>> service provider requires dot1q tagging. As such, I must shape my
>>>> sub-interface and use a hierarchical type QoS policy...no big deal
>>>>
>>>> policy-map WAN-EDGE
>>>> class VOICE
>>>> priority percent 20
>>>> !
>>>> class VIDEO
>>>> bandwidth remaining percent 60
>>>> queue-limit 128 packets
>>>> !
>>>> class APPS_SIGNALING
>>>> set dscp af21
>>>> bandwidth remaining percent 30
>>>> !
>>>> class class-default
>>>> bandwidth remaining percent 10
>>>> !
>>>> !
>>>> policy-map SHAPE-OUT
>>>> class class-default
>>>> shape average 10000000
>>>> service-policy WAN-EDGE
>>>> !
>>>> !
>>>> int gi0/1.2
>>>> encapsulation dot1q 2
>>>> ip address ...
>>>> service-policy output SHAPE-OUT
>>>>
>>>>
>>>> Here is the very strange thing. Even when the TX of this WAN
>>>> interface
> is
>>>> barely being used, when and only when the service-policy is
>>>> applied, the response in pings to anything behind this router
>>>> increase immediately by 200-400ms. Immediately after removing the
>>>> service-policy things return
> to
>>>> normal.
>>>>
>>>> Investigating the output of "show policy-map interface" reveals a
>>>> large number of output drops in the shaper class-default. So far I
>>>> have tried
>>>>
>>>> - increasing the queue-limit to many different combinations
>>>> - increasing the burst size
>>>>
>>>> I also have the exact same configuration on another remote site
>>>> router running the same version of IOS with the same setup (10Mbps
>>>> Ethernet WAN
>>>> link) on the same platform.
>>>>
>>>> I'm really baffled as to what would cause this. Any insight
> appreciated.
>>>>
>>>>
>>>>
>>>> --
>>>> Regards,
>>>>
>>>> Joe Astorino
>>>> CCIE #24347
>>>> http://astorinonetworks.com
>>>>
>>>> "He not busy being born is busy dying" - Dylan
>>>
>>>
>>>
>>> --
>>> Regards,
>>>
>>> Joe Astorino
>>> CCIE #24347
>>> http://astorinonetworks.com
>>>
>>> "He not busy being born is busy dying" - Dylan
>>>
>>>
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>>
>>
>>
>>
>>
>>
>>
>> --
>> Regards,
>>
>> Joe Astorino
>> CCIE #24347
>> http://astorinonetworks.com
>>
>> "He not busy being born is busy dying" - Dylan
>>
>>
>>
>> --
>> Regards,
>>
>> Joe Astorino
>> CCIE #24347
>> http://astorinonetworks.com
>>
>> "He not busy being born is busy dying" - Dylan
>
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>
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Received on Fri Apr 19 2013 - 22:32:36 ART