Re: QOS on Catalyst 2960

Hey team,

Good evening to all and I hope this finds each of you doing well.

I love this line "cisco Qos is good in theory, but a pain in practice.
please help :( "

After reading this line, I can agree that all the options avail / "nerd
knobs" and detail functionality can be over whelming... so with this said,
for the lab, learn the CLI ... in the real world check smart port macros and
see if they fit. 9 out of 10 times they will work just fine for whatever
task is at hand...

I might suggest to configure this with smart ports and then see what config
is automatically done for you. A lot of configs are done automatically ...
so a good learning this is.

To your earlier question, are you asking why the switch is not changing the
L3 header to make the DSCP value to 24?

Was the packet originally marked as 24? If so, why not just trust the
DSCP? Hummm ...

Perhaps it is not clear what you are trying to accomplish. If you have a
phone attached, try and smart port and then check the 75 lines of config
added, if you understand all that is being done, then you have a good grasp
on L2 Qos. ;-)

HTH,

Andrew Lissitz

On Sat, Jul 23, 2011 at 7:18 PM, Carlos G Mendioroz <tron_at_huapi.ba.ar>wrote:

> May I ask how are you capturing the packet to validate that it is not
> working ? Do you have a host connected to the trunk ? (i.e. a PC ?)
> Are you seeing the 802.1q tag ?
>
> Cause it should work, it does on my 2950 :)
> -Carlos
>
> Irfan Sid @ 23/07/2011 16:50 -0300 dixit:
>
> cisco Qos is good in theory, but a pain in practice. please help :(
>>
>>
>> I have a 2960 Catalyst switch with LAN Base.I have set my inbound cos
>> value
>> to be a configurable value of cos 3 on fa0/2 (to mark all inbound frames).
>> I
>> understand from Cisco documentation, that this COS value will not be
>> written
>> into the Ethernet frame, but used to derive an *"Internal"* DSCP value or
>> QOS Label if you will. This internal DSCP is derived from the COS-DSCP
>> map,
>> which in my case maps Cos3 to DSCP 24. (cs3)
>>
>>
>>
>> This internal DSCP value of 24 should then be written back to a COS value
>> if the outgoing interface is a trunk based on the DSCP-COS Map. In my case
>> which is using the default mapping of DSCP 24 being mapped to Cos 3.
>> However
>> when I run a packet capture on the outgoing interface, I do not see the
>> frame marked with Cos 3.
>>
>>
>>
>> Below is my configuration, please can you advise....
>>
>>
>>
>>
>>
>> mls qos map cos-dscp 0 8 16 24 32 46 48 56
>>
>> mls qos
>>
>> !
>>
>> interface FastEthernet0/1
>>
>> switchport mode trunk
>>
>> !
>>
>> interface FastEthernet0/2
>>
>> switchport access vlan 100
>>
>> mls qos cos 3
>>
>> mls qos cos override
>>
>>
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>>
>>
>>
>>
>>
> --
> Carlos G Mendioroz <tron_at_huapi.ba.ar> LW7 EQI Argentina
>
>
>
> Blogs and organic groups at http://www.ccie.net
>
> ______________________________**______________________________**
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> list/CCIELab.html <http://www.groupstudy.com/list/CCIELab.html>
>
>
>
>
>
>
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>

-- 
Andrew Lee Lissitz
all.from.nj_at_gmail.com
Blogs and organic groups at http://www.ccie.net