QoS on 3750X

[Sebastian Helmer]

Dear all,

today I configured the folowwing QoS config. It seems to work, OR do you have any comments...I want to limit the Exchange traffic comming from the DataCenter to the location to 10Mbit (Download of big OST Files due to the Exchange migration).

class-map match-all LIMIT_EXCHANGE

match access-group 100

!

!

policy-map LIMIT_EXCHANGE

class CIFS

  police 10000000 1000000 exceed-action drop

interface gig X/0/XX

Provider_Router

service-policy input LIMIT_EXCHANGE

access-list 100 permit ip host Exchange-IP1 any

access-list 100 permit ip host Exchange-IP2 any

access-list 100 permit ip host Exchange-IP3 any

regards,
Sebastian

[mgalazka]

Sebastian,

Thanks for posting a nice short write-up on a problem and solution, it may help others in the future. I do have a couple comments:

1. The class name in your policy-map does not match the class-map you defined above. From your post, it appears the policy-map should have nested "class LIMIT_EXCHANGE" instead of "class CIFS".

2. You may find that using "shape average" instead of "police" gives better overall throughput.

Thanks for sharing!

Matt

[Sebastian Helmer]

Thanks for your reply..The naming problem, is already solved, sorry..

I will check out the shape option, thank you!

regards,
Sebastian

[Joseph W. Doherty]

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Posting

2. You may find that using "shape average" instead of "police" gives better overall throughput.

The 3750X doesn't allow generic traffic shaping.  However, if you can map this traffic to a specific egress queue, you can shape the queue.

Perhaps better yet, if you can map this traffic to a specific egress queue, you can allocate it a bandwidth proportion.  Done correctly, this traffic would be only given a set bandwidth proportion (such as your 10 Mbps) when there's contention for the bandwidth, but it could use more if it was otherwise not being used.

[mgalazka]

Ah, thanks JosephDoherty. I forgot, 3750X uses the "SRR" style QoS configuration. Agreed with your latter point as well, glad you added your comments!

Matt

[Sebastian Helmer]

thanks all,

Joseph, do you have an example for the engress queue config?

[Joseph W. Doherty]

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

Joseph, do you have an example for the engress queue config?

I might, it depends on what exactly you want an example of.

Egress queues (4) are enabled when you enable QoS on a 3750X.

They start with a default configuration, to which there's quite a few commands and parameters to change, if you chose to do so.  This is different from a software router's QoS where you usually start with a single FIFO and they you define how QoS will be configured.

Many of the commands are global, i.e. they will impact all the interfaces.  Again much different from a router's per interface QoS configuration.

For you case, you would need an ingress policy to classify and mark traffic, global commands to define how markings get mapped to the built-in egress queues, perhaps global buffer and WTD settings and finally egress queue bandwidth ratios for a particular interface.