QoS between 3750-ISP-3750

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May 18th, 2009
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I've link between my 2 office - 100mb.

And i need config qos - for phone and buisness.

Provider can not help me - they also drop all marking traffic.

I want push 100 calls and all critical traffic when i have congestion.

But i have no idia - what i must do with traffic next. Any body can help me?

That is all i can do.

class-map ClassVoIP

match access-group name VoIP

class-map Critical

match access-group name Critical



policy-map QoSCriticalMap

class VoIP

class Critical


interface FastEthernet0/0

bandwidth 1024000

service-policy output QoSCriticalMap


ip access-list extended VoIP

permit udp any

permit tcp any

ip access-list extended Critical

permit tcp any any eq 21

permit udp any any eq 21

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vishwancc Mon, 05/18/2009 - 01:35
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Hi Kuda,

You need you ISP to do QOS for End-to-End Qos to work,even if you apply QOS on traffic going out of your network ,the ISP will not treat it the way you want to.



Joseph W. Doherty Mon, 05/18/2009 - 02:34
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"Provider can not help me - they also drop all marking traffic. "

You should clarify/verify this. Providers often will not honor QoS markings and they sometimes will reset markings, but they shouldn't be dropping packets/frames just because they are marked. You should also ask about L2 vs. L3 markings.

Assuming provider doesn't drop packets/frames, and assuming there's only your two sites in communication, you should be able to organize and queue traffic into at least 4 classes before forwarding traffic across link.

If the device is a 3750 (non Metro variant), your options are explained in the QoS section of the configuration guide. e.g. http://www.cisco.com/en/US/docs/switches/lan/catalyst3750/software/release/12.2_50_se/configuration/guide/swqos.html. Take special note one of the four queues can be configured for priority (i.e. greate for VoIP bearer).

If the 3750 is a Metro variant, there are some additional QoS options. Again, configuration guide is a good place to start, e.g. http://www.cisco.com/en/US/docs/switches/metro/catalyst3750m/software/release/12.2_50_se/configuration/guide/swqos.html.


"But i have no idia - what i must do with traffic next. Any body can help me? "

If QoS concepts are new to you, you might also want to examine various QoS design guides, e.g. http://www.cisco.com/en/US/docs/solutions/Enterprise/WAN_and_MAN/QoS_SRND/QoSIntro.html and http://www.cisco.com/en/US/docs/solutions/Enterprise/WAN_and_MAN/QoS_SRND/QoSDesign.html#wp999395.

kudachkin Mon, 05/18/2009 - 05:42
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ISP cannot give me QoS.

All i can do - it push traffic, in my order.

But question is - on router - a can use bandwith % - on 3750 - cannot.

Joseph W. Doherty Mon, 05/18/2009 - 06:06
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"Normal" 3750s don't support router CBWFQ, but they do allow you to set ratios between 4 output queues. I.e. you can determine order of your traffic.

The references I provided in my first post provides details.


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