07-18-2012 04:31 PM - edited 03-03-2019 06:41 AM
Hi.
I've been reading the forum and the net trying to get a straight answer on this and can't seem to find anything concrete.
So basically If I have a CBWFQ setup for three classes, af3x (55%), af2x(30%) and class default(15%). applied outgoing on a WAN interface.
policy-map CBWFQ-POLICY
class Af3x
bandwidth percent 55
random-detect
class Af2x
bandwidth percent 30
random-detect
class class-default
bandwidth percent 15
random-detect
Now I get that in normal operation all classes will burst either way and during congestion, traffic in a specific class will be guaranteed it's bandwidth
.
But how is unused bandwidth from a class allocated during congestion. So for example if I have this link being congested primarily with Af2x and default traffic but have available capacity in Af3x, for this example say I have 30% AF3x still available.
Will the router split it evenly15% Af2x and 15% default or will it split proportionatly based on the original BW allocations, ie 20% Af2x and 10% default.
Thanks
Solved! Go to Solution.
07-24-2012 06:12 AM
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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.
Posting
What actually happens is the scheduler assigns weights to classes based on the bandwidth specification. Class flows get their relative bandwidth based on the weight. So, for example, if your class AF3x was using no bandwidth, and AF2x and class-default wanted all the bandwidth, they would split it 2:1 (30:15).
07-19-2012 06:20 AM
AF stands for assured forwarding and does not limit the amount of traffic that can go through. It actually is not that important anyway to define a class as AF2x as much as defining a class as AF21 or AF22 etc...
Remember that AF21 has not real priority over AF31 or AF41. The "x" value is the one giving priority, the higher (e.g. AF33) the weaker (it will be drop first).
My suggestion anyway is to hierarchically shape the traffic in your classes.
HTH
Alessio
07-20-2012 02:57 AM
If your first class is not using all of its allotted bandwidth then the other two classes will use the available bandwidth based on the percentages you define in the other classes. That is, only if their bandwidth needs allow it. If your second class also doesn't need it then your default class will use it all if it needs it.
07-24-2012 06:12 AM
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
What actually happens is the scheduler assigns weights to classes based on the bandwidth specification. Class flows get their relative bandwidth based on the weight. So, for example, if your class AF3x was using no bandwidth, and AF2x and class-default wanted all the bandwidth, they would split it 2:1 (30:15).
07-27-2012 12:41 AM
Thanks for the help guys, this has cleared things up
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