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Limiting traffic rates on 3560 Switchports

OK I daresay this question has probably been asked many times before in a slightly different way but I'm struggling to find an answer for my scenario.

I have a 3560 switch where I have 4 ports connected, one is to our WAN provider - 10Mbps and the other three are connected to different customers who I want to get an equal share of the 10Mbps bandwidth.

I'm fairly clued up about configuring modular QoS but I'm being thrown by the fact that you can't apply a service-policy outbound on the ethernet ports.

Anybody able to give me a suggestion on the best way to achieve this?

  • LAN Switching and Routing
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Super Bronze

Re: Limiting traffic rates on 3560 Switchports

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

A 3560 supports 4 egress queues, so for your three customers, you could assign each one their own queue with a 1/3 bandwidth ratio allocation.  Each would get equal bandwidth when they compete for it, more if it's available.

Although the prior well supports egress bandwidth sharing, sharing ingress bandwidth is more problematic.  You could police the inbound bandwidth such that each customer cannot utilize more than 1/3 of the bandwidth, but then they would be unable to utilize available bandwidth and policing downstream doesn't maintain bandwidth restriction under all situations.

3 REPLIES

Limiting traffic rates on 3560 Switchports

Hi Dave,

You should be able to add the service policy as an outbound in 3560.

eg as shown below:

ip access-list extended qos-basic-services

permit udp any any eq 53

permit tcp any any eq 25

deny ip any

!

class-map match-all cm_qos-basic-services

match access-group name qos-basic-services

!

policy-map pm_qos-basic-services

class-map cm_qos-basic-services

set dscp xxxx

!

interface FastEthernet 0/[1-24]

service-policy input pm_qos-basic-services

!

Apart from these you have to define the Qos cos/dscp marking, shaping & bandwidth accordingly...

Please do rating if the given information helps.

Regards

Karthik

Re: Limiting traffic rates on 3560 Switchports

Hi Dave,

apply policing/shaping only if really required.

http://www.cisco.com/en/US/docs/ios/12_2/qos/configuration/guide/qcfpolsh.html

very brief doc but very cool.

HTH

Alessio

      

PS: no question will ever be asked too many times....

Super Bronze

Re: Limiting traffic rates on 3560 Switchports

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

A 3560 supports 4 egress queues, so for your three customers, you could assign each one their own queue with a 1/3 bandwidth ratio allocation.  Each would get equal bandwidth when they compete for it, more if it's available.

Although the prior well supports egress bandwidth sharing, sharing ingress bandwidth is more problematic.  You could police the inbound bandwidth such that each customer cannot utilize more than 1/3 of the bandwidth, but then they would be unable to utilize available bandwidth and policing downstream doesn't maintain bandwidth restriction under all situations.

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