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CBWFQ on Switch Catalyst 3750

Erico Verissimo
Level 1
Level 1

Does Switch cisco Catalyst 3750 support CBWFQ QoS?

I would like to understand if the IOS of the catalyst support the Bandwidth command to a class and offer a minimum bandwidth in congestion situation. I have some applications that need to increase its flow when the other classes is not using their bandwidth. On my 3750 I dont see the bandwidth command.

Thanks a lot. 

1 Accepted Solution

Accepted Solutions

Hi you should not have to set mls qos, just use the service policy to apply it but from what i remember there's restrictions on 3750s i dont think you can apply the policy outbound only inbound but it may have changed in newer IOS, i have not tested it recently

 This is a good doc on 3750s qos

http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3750/software/release/12-2_52_se/configuration/guide/3750scg/swqos.html#wp1766985

View solution in original post

7 Replies 7

Mark Malone
VIP Alumni
VIP Alumni

Yes 3750s support CBWFQ , its not about the hardware more the software thats running on it as its layer 3 software based qos unlike layer 2 which is hardware based qos

Hi Mark,

Thank you for response. 

So I need to enable the (mls qos) to use the cbwfq or I can to make the follow config without mls qos:

policy-map xxxx
 class critical_data
  set ip dscp af41
    bandwidth percent 50
     random-detect dscp-based
     random-detect dscp 34 50 105
    queue-limit 148 packets


 class oam_map
  set ip dscp cs2
    bandwidth percent 5

 class voip_map
  priority percent 6 

set ip dscp ef

 class svoip_map
  set ip dscp af31
    bandwidth percent 3

 class pacs_map
  set ip dscp af13
    bandwidth percent 20

 class class-default
    fair-queue
     random-detect dscp-based

 

Thanks

Hi Mark,

Thank you for response.

In this case, when I use bandwidth command it´s possible a class use the bandwidth that is not in use for other class. In 3750x I only able to use police that limit my class and if it necessary more bandwidth and other class is not using all its band this class dont increase its band to be using police. Does it make sense Mark? Is it correct?

 

Thanks.

Hi you should not have to set mls qos, just use the service policy to apply it but from what i remember there's restrictions on 3750s i dont think you can apply the policy outbound only inbound but it may have changed in newer IOS, i have not tested it recently

 This is a good doc on 3750s qos

http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3750/software/release/12-2_52_se/configuration/guide/3750scg/swqos.html#wp1766985

Hi thank you, this doc will help me!!

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Posting

(A very belated response - but just stumbled across this thread - I believe some response information might not be 100% accurate.)

Yes 3750s support CBWFQ . . .

At least for egress, it is not like software based routers.  Feature wise, it's a subset, and its configuration can be quite different.

. . .  its not about the hardware more the software thats running on it as its layer 3 software based qos unlike layer 2 which is hardware based qos

3750 QoS is tied to its hardware, especially for egress.

Thank you for your response.

Cheers.

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