Configure "linear-red-profiles" on an ATM interface

09.08.09   |  
‎09-08-2009 10:02 AM

Hi Group,


I would like to configure "linear-red-profiles" on an ATM interface. I have found only this technical document: http://www.juniper.net/techpubs/software/junos/junos85/swconfig85-network-interfaces/id-10790945.html#id-10790945.


It is not very clear how to configure the different statements (high-plp-max-threshold, low-plp-max-threshold, queue-depth, high-plp-threshold and low-plp-threshold).

I would like to configure CoS to differentiate two kinds of traffic in a queue. 20% of "high-plp" and 80% of "low-plp".


Thanks for your help and explanations.





Re: Configure "linear-red-profiles" on an ATM interface

[ Edited ]
09.08.09   |  
‎09-08-2009 12:35 PM

Hello Samuel,


The principal is the following: a linear-red profile has the following parameters:

- queue-depth: maximum queue-depth in cells - above this value, packets are always dropped

- high(/low)-plp-threshold: percentage of queue-depth, above which packets start to be dropped randomly

- high(/low)-plp-max-threshold: percentage of queue-depth, above which packets are dropped with 100% probability


Between the 2 thresholds the drop probability is linear (hence the name). 

 These parameters are associated with queues (= forwarding-classe) in the scheduler-map.


Here is a config example:


linear-red-profiles {

be_red_2mb queue-depth 1040 high-plp-threshold 1 low-plp-threshold 25 high-plp-max-threshold 25 low-plp-max-threshold 100;


forwarding-class be {

priority low;

transmit-weight percent 20;

linear-red-profile be_red_2mb;



In this example, when the queue-depth (of the BE class) reaches roughly 63 cells (half-way between 1 and 25%) then we drop high-PLP packets with a 50% chance - but we do not start dropping low-PLP packets before about 125 cells.

High-PLP packets will always be dropped when the queue exceeds 1010 cells whereas low-PLP packets can completely fill the queue.






Message Edited by davidjdv on 09-08-2009 09:37 PM

Re: Configure "linear-red-profiles" on an ATM interface

09.09.09   |  
‎09-09-2009 12:50 AM

Thanks David! Smiley Happy