Help with QoS

[Itap]

Hello

I want to configure QoS to prioritize bandwidth for one ip address.

Sometimes link bandwidth overflows. When overflow occurred for one ip address we must guarantee 5 mbits

Please see config

acl 100 permit ip any host x.x.x.x

class-map match-any llq-class
match access-group 100

policy-map llq-policy
class llq-class
priority 5000

interface fa 0/0
service-policy output llq-policy

Is this config will work ?

2. If there are no flows that match these class, is it available for other traffic?

thx

[John Blakley]

1. This will work..

2. The policy is only in effect when the link is saturated. Otherwise, the bandwidth will be spread out among the other classes (class-default in your case)

HTH,

John

[Itap]

Oh, thanks.

1. It means I dont need to create class-default ?

class class-default

  bandwidth remaining percent ???

2. If you know why need this command ?

[John Blakley]

Class-default is there even if you don't see it. It matches anything that wasn't previously matched to another class in the same policy. The "bandwidth remaining percent" allows for a guarantee for any traffic that falls into this class, so you can definitely do that if you want to make sure that the other queues don't starve out the class-default in times of congestion.

[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.

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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

As John notes, what you have should work, however using LLQ can also cap your special IP at 5 Mbps.  Additionally, LLQ is normally just used for guaranteeing the least latency, i.e. you could use just a bandwidth statement to guarantee a minimum of 5 Mbps.

[Itap]

This output from cisco 7200

Babilon-T-MSK#show policy-map interface fa 0/0
fastethernet 0/0

Service-policy output: llq-policy

Class-map: llq-class (match-all)
83482 packets, 92815711 bytes
30 second offered rate 7879000 bps, drop rate 0 bps
Match: access-group 101
Queueing
queue limit 64 packets
(queue depth/total drops/no-buffer drops) 0/0/0
(pkts output/bytes output) 83482/92815795
bandwidth 100 kbps

Class-map: class-default (match-any)
2355947 packets, 1248583096 bytes
30 second offered rate 103608000 bps, drop rate 0 bps
Match: any

queue limit 64 packets
(queue depth/total drops/no-buffer drops) 0/0/0
(pkts output/bytes output) 2356000/1248608592

I used bandwidth and priority in policy-map

I configured bandwidth and priority equal to 100kbps

But my download speed was 7 or 9 mbits

I think this seems strange....

Please correct me if I wrong

[Itap]

bandwidth command  guarantee minimum 5 mbits. So it works ???

How about priority command it also  guarantee minimum 5 mbits ???

[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

Correct, CBWFQ bandwidth sets a minimum; class can use more bandwidth if its available.

CBWFQ priority also set a minimum, but it also sets a maximum if there's congestion.