[j-nsp] Priority Queuing

Harry Reynolds harry at juniper.net
Fri Jan 20 16:36:02 EST 2006


I find this white paper to be useful:

http://www.juniper.net/solutions/literature/white_papers/200020.pdf


When you configure a scheduler you indicate a priority of low, high, or
strict-high.

lab at San_Jose# show schedulers   
be-scheduler {
    transmit-rate 1m exact;
    priority low;
    drop-profile-map loss-priority low protocol tcp drop-profile
low-red;
    drop-profile-map loss-priority high protocol tcp drop-profile
high-red;
}
ef-scheduler {
    transmit-rate 20m;
    buffer-size temporal 200000;
    priority high;
}
nc-scheduler {
    transmit-rate percent 5;
    priority low;
}

The DWRR services high priority with positive, until they go negative,
then it moves on to service low priority with positive credit. A strict
high queue has a weight that is equal to the interface's speed, so it
can never go negative. A strict-high queue can starve a low priority
queue, but not another high priority queue with positive credit. 

A strict-high and a high priority queue that are both positive are
serviced in a round-robin manner. So, generally speaking if you use a
strict-high it is a good idea to define the NC queue as high to ensure
that control signaling is not starved.

HTHs




> -----Original Message-----
> From: juniper-nsp-bounces at puck.nether.net 
> [mailto:juniper-nsp-bounces at puck.nether.net] On Behalf Of 
> Byron L. Hicks
> Sent: Friday, January 20, 2006 1:12 PM
> To: juniper-nsp at puck.nether.net
> Subject: [j-nsp] Priority Queuing
> 
> *** PGP SIGNATURE VERIFICATION ***
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> 
> Is there a good docuement on how to use priority queueing on 
> a Juniper router?  I know how to set ip on a Cisco, but I 
> can't seem to find the equivalent Juniper config.
> 
> 
> --
> Byron L. Hicks
> Network Engineer
> NMSU ICT/CHECS-NET
> 
> *** END PGP VERIFIED MESSAGE ***
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