Best Effort QoS Drop Profile Input

Brad Fleming bdfleming at kanren.net
Mon Aug 24 10:36:56 CDT 2009


Hello all,

We are working on fine tuning drop profiles for customer edge routers  
(Juniper J-2320 in almost all cases) and I was hoping for some input  
from those who are smarter and have done this before.

Basics:
- Sites each have a single T1 into a service provider L3 VPN
- Queue depth is 500ms
- Sites typically will use 90%+ of their line rate while school is in  
session (education network)
- Services offered include: real-time video (in a different queue) and  
best effort (serviced by the queue in question)
- Nearly all BE traffic will be TCP (typical web, email, etc traffic)

We were never able to find a good best practice for configuring drop  
profiles on edge devices. We've been using the following with OK  
results but I was hoping to have some external, more experienced eyes  
take a look...

drop-profiles {
     be_any {
         fill-level 50 drop-probability 5;
         fill-level 70 drop-probability 20;
         fill-level 90 drop-probability 50;
     }

Has anyone ever run across a publicly documented best practice for  
drop profile configuration?
Does anyone have suggestions on ways to improve the configuration above?

Any input is much appreciated, thanks in advance!

-brad fleming


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