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New Member

Issue with trust CoS on ES+ linecard

Hi all,

I have some troubles with QoS on ES+ linecard. I cannot trust CoS on GEports of ES20+ linecard. So, I don't know what to do with these traffics received from DSLAM/L2SW. Is there anyone who has experience with this issue? Please tell me what to do ?

(My router is 7609, running SRE3)

Thanks,

Hieu

3 ACCEPTED SOLUTIONS

Accepted Solutions
Cisco Employee

Issue with trust CoS on ES+ linecard

Hi Hieu,

how you could see by yourself mls trust cos is not supported on ES+ cards as the trust concept does not exist on this card.

However you have a viable option.

That is what is suggested in the ES+ QoS Configuration guide under the Ingress Trust paragraph:

http://www.cisco.com/en/US/docs/routers/7600/install_config/ES40_config_guide/es40_chap7.html#wp1346147

"The ES+ line card marks a packet as trust cos when ingress marking for CoS is configured for a routed interface. Hence, the CoS value configured using the set cos value command is retained on the outgoing packet. This cos value is not overwritten by earl or derived from dscp."

So you can apply a policy map which mark traffic with a given cos value which will be preserved in the outgoing packet.

hope this helps

regards,

Riccardo

Cisco Employee

Re: Issue with trust CoS on ES+ linecard

Hi Hieu,

yes correct, you can mark COS on a policy attached to the interface.

Please aslo note that if you use EVC with bridged group instead the deafult behavior is to trust cos, meaning that you don't need to take any other extra action.

About the differencies between ES20 and ES+ cards they are completely different. ES20 (like the SIP-600) uses PFC3/DFC3 based QoS. That is why you have the trust concept which is typical for MLS (and therefore PFC/DFC based) QoS.

On the other hand ES+ is like software routers (i.e. 7200) and uses distributed MQC QoS model and does not use the PFC/DFC for the purpose. Same approach on Flexewan and SIP-200 and 400.

Please rate the answer and close the question if you are happy with it.

Riccardo

Cisco Employee

Re: Issue with trust CoS on ES+ linecard

Hi Hieu,

I confess that I had to check that case before remembering you It is nice talking with you again.

About EVC I refer to Ethernt Virtual Connections (or Circuits) which is a flexible way to configure L2 and L3 services on SP devices.

ES20 and ES+ ports allow you to configure Service Instances which are Ethernet Flow Points (EFPs) within the EVC frame.

You can see more on

http://www.cisco.com/en/US/docs/switches/lan/catalyst6500/ios/12.2SY/configuration/guide/ethernet_virtual_connection.html

or on similar pages on ES+ configuration guides.

So if your traffic arrives to an ES+ port configured with EVC in an EFP with bridge group the default behavior is to trust the cos value.

Riccardo

6 REPLIES
Cisco Employee

Issue with trust CoS on ES+ linecard

Hi Hieu,

how you could see by yourself mls trust cos is not supported on ES+ cards as the trust concept does not exist on this card.

However you have a viable option.

That is what is suggested in the ES+ QoS Configuration guide under the Ingress Trust paragraph:

http://www.cisco.com/en/US/docs/routers/7600/install_config/ES40_config_guide/es40_chap7.html#wp1346147

"The ES+ line card marks a packet as trust cos when ingress marking for CoS is configured for a routed interface. Hence, the CoS value configured using the set cos value command is retained on the outgoing packet. This cos value is not overwritten by earl or derived from dscp."

So you can apply a policy map which mark traffic with a given cos value which will be preserved in the outgoing packet.

hope this helps

regards,

Riccardo

New Member

Issue with trust CoS on ES+ linecard

Hi Riccardo,

Thank you for your response. We also use ES20 in our network and trust CoS can be done normally on these cards. So, with ES+, we have to configure poilicy to set the CoS for the traffics which have already marked from L2SW/DSLAM, right?

Why there is a different between ES20 and ES20+? Could you help me to answer this question?

Thank you,

Hieu

Cisco Employee

Re: Issue with trust CoS on ES+ linecard

Hi Hieu,

yes correct, you can mark COS on a policy attached to the interface.

Please aslo note that if you use EVC with bridged group instead the deafult behavior is to trust cos, meaning that you don't need to take any other extra action.

About the differencies between ES20 and ES+ cards they are completely different. ES20 (like the SIP-600) uses PFC3/DFC3 based QoS. That is why you have the trust concept which is typical for MLS (and therefore PFC/DFC based) QoS.

On the other hand ES+ is like software routers (i.e. 7200) and uses distributed MQC QoS model and does not use the PFC/DFC for the purpose. Same approach on Flexewan and SIP-200 and 400.

Please rate the answer and close the question if you are happy with it.

Riccardo

New Member

Re: Issue with trust CoS on ES+ linecard

Hi Ricardo,

I had a chance to work with you in a TAC-case related to ES+ problem before, do you remember? (SR 614028961 - 7600CU: ES20+ problem) I'm very glad to take this opportunity to discuss with you and I'm so happy with your answers again.

But can you do me one more favor : what do you mean when you said " if you use EVC with bridged group instead the deafult behavior is to trust cos, meaning that you don't need to take any other extra action" ? Please help to explain that?

Thank you,

Hieu

Cisco Employee

Re: Issue with trust CoS on ES+ linecard

Hi Hieu,

I confess that I had to check that case before remembering you It is nice talking with you again.

About EVC I refer to Ethernt Virtual Connections (or Circuits) which is a flexible way to configure L2 and L3 services on SP devices.

ES20 and ES+ ports allow you to configure Service Instances which are Ethernet Flow Points (EFPs) within the EVC frame.

You can see more on

http://www.cisco.com/en/US/docs/switches/lan/catalyst6500/ios/12.2SY/configuration/guide/ethernet_virtual_connection.html

or on similar pages on ES+ configuration guides.

So if your traffic arrives to an ES+ port configured with EVC in an EFP with bridge group the default behavior is to trust the cos value.

Riccardo

New Member

Re: Issue with trust CoS on ES+ linecard

Hi Riccardo,

Thank you for your support!

I will try to configure ES+ port with EVC in an EFP with bridge group in my Lab first and let you know about the results.

Regards,

Hieu

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