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max-reserved-bandwidth on T1

I have a serial T1 going to a remote site, running BGP.  We have a service-policy on the interface with various QOS classes with bandwidth remaining percent X statements. 

However I noticed the serial interface has max-reserved-bandwidth 100 on the interface.  Isn't that not recommended?  I know the default is 75% available, and lots of people increase that.  But shouldn't 100% be avoided -- to save room for control-plane traffic (BGP)?

What's realistic?  90%?

Thanks

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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.

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On pre-HQF CBWFQ, max-reserved controls how much bandwidth you can allocate/define to classes other than class-default.  Pre-HQF only allowed defining 75% for all non-default classes unless you overrode with the max-reserved command.

As to whether defining all 100% for non-default traffic is a good idea or not, really depends on what traffic will be in class-default and its needs.  For example, you mention BGP.  If BGP bandwidth reservation is a concern, then yes you might insure there's sufficient bandwidth for it, but as you could direct it to a dedicated non-default class, class default might be fine with zero percent.  (Actually even if class-default was logically defined with zero, unless all other 100% was defined to LLQ, class-default will still get some bandwidth.)

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VIP Expert

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


On pre-HQF CBWFQ, max-reserved controls how much bandwidth you can allocate/define to classes other than class-default.  Pre-HQF only allowed defining 75% for all non-default classes unless you overrode with the max-reserved command.

As to whether defining all 100% for non-default traffic is a good idea or not, really depends on what traffic will be in class-default and its needs.  For example, you mention BGP.  If BGP bandwidth reservation is a concern, then yes you might insure there's sufficient bandwidth for it, but as you could direct it to a dedicated non-default class, class default might be fine with zero percent.  (Actually even if class-default was logically defined with zero, unless all other 100% was defined to LLQ, class-default will still get some bandwidth.)

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