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Community Member

3560 switch - LAN QoS

HI Experts,

I have issue with 3560 switch QoS configuration . I checked in cisco site about mentioned model QoS configuration.

once we mark the frame and map the CoS to DSCP and once it enters into switch and it processes  according to LAN QoS configured on interface

we have configured  both the commands shape and share.

once it leaves the switch and enters into Edge router and if we do not have configured QoS in router which is normally MQC  , how does it process each packet ?

Do we need to have end to end QoS configured in LAN ?

Thanks ,


Everyone's tags (5)

3560 switch - LAN QoS

no if we do Qos on the access layer that would be suffice. we don need to mention on each and every layer of the network. WAN end router should have the configuration that should honour the cos mappings as it is defined in the access layer. Just we need to have have the qos trust on all the interfaces of the layers that is connected to the access switch till the WAn router.

Example Scenario:


Access -- Qos policy applied


Distribution --- Qos Trust


Core          --- Qos trust


Edge Rtr    --- Qos trust


WAN rtr     --- Qos Trust

Re: 3560 switch - LAN QoS

Hello Vinod,

I agree partially with Karthikeyan on having QoS at access layer. But frankly speaking, it should be end-to-end. Think in this way, if your uplink from access to distribution is choked due to some "worm" attack within your network, you may have a congestion within your LAN as well. During that point, you must have a well defined queuing policy for the critical traffic to be served first.

Best practices

1) Classification / Marking : Access

2) Queuing : Access, Distribution, Core

3) Policing, shaping : distribution & Core.

NOTE : You may need to remark your traffic at core level to match the service provider's CoS sometimes.

Hope this helps.



Community Member

3560 switch - LAN QoS


NOTE : You may need to remark your traffic at core level to match the service provider's CoS sometimes.

QFT.. I reckon as a best practice, remarking the traffic at the core level is a must as I have seen ISP routers sometimes not able to pick up the markings made by the downstream switches.. in all my implementations, I have remarked the traffic at the core level after there were quality issues reported..

3560 switch - LAN QoS

You right. Remarking is almost done everytime on the core to adhere to the Service provider CoS. Without that, every other marking not matching to the CoS specified by SP would be treated as a "Best effort". So, quality issues may occur 

3560 switch - LAN QoS

Hi Vivek,

Yes. I concurr with your statement.... We need to have qos trust as well as the queuing in the distribution layer and in core layer we need to have the policing and shaping... if we have any shaping device like packet teer we can have the shaping done in that... if not we need to do that in core switches..


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