04-15-2013 08:05 AM - edited 03-01-2019 02:39 PM
Hello Everyone,
I'm studying QoS and I'm wondering how does a Cisco Engineer find out what the best Minimum and Maximum Threshold rates are when using WRED?
Where would one find these values?
I'm under the impression that it requires a study that's based on the size of the queues, is that correct?
But then, I come to the conclusion that even if the queues are big enough, application critical data like (VOIP) would suffer from delay..
So, how do you calculate the min and max threshold values..
Thanks ahead of time..
PR
Solved! Go to Solution.
05-07-2013 08:13 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.
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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
Setting WRED parameters, for optimal performance, is (IMO) very tedious. Lots of variables involved.
For starters, it shouldn't normally be applied to traffic that's not rate-adaptive, such as VoIP.
It works best for multiple large bulk data transfer TCP streams that are using dropped packets for their principle flow control. Then it can be optimized to maximize their "goodput".
To answer your question, you might study RED literature, and its many variants, found on the Internet.
You also want to study, if you're not already very familiar, with how adaptive flow rate protocols, such as TCP, behave when packets are dropped. (With TCP also be mindful of the different "flavors", i.e. Tahoe, Reno, New-Reno, etc.)
If you have specific questions, post again to this thread, and I might be able to help.
05-07-2013 08:13 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
Setting WRED parameters, for optimal performance, is (IMO) very tedious. Lots of variables involved.
For starters, it shouldn't normally be applied to traffic that's not rate-adaptive, such as VoIP.
It works best for multiple large bulk data transfer TCP streams that are using dropped packets for their principle flow control. Then it can be optimized to maximize their "goodput".
To answer your question, you might study RED literature, and its many variants, found on the Internet.
You also want to study, if you're not already very familiar, with how adaptive flow rate protocols, such as TCP, behave when packets are dropped. (With TCP also be mindful of the different "flavors", i.e. Tahoe, Reno, New-Reno, etc.)
If you have specific questions, post again to this thread, and I might be able to help.
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