[j-nsp] CoS/QoS

[Erdem Sener]

Hi,

 Basically you should decide on the model you're going to use for
CoS/QoS. If you only plan to "prioritize" a couple of subnets and sure
your network/needs won't grow larger in the near future, you could
start with firewall filters that just redirect the traffic towards
different queues. For long term usage, you might choose something like
DiffServ model and mark the packets first, then treat them based on
their values backbone wise.

Basically, for CoS you'll need to define a couple of things under
[edit class-of-service] level.

Classifiers: if you choose the DiffServ model,. this is where you
(sort of) associate dscp values with forwarding classes. a snip
configuration might look like:
dscp access_dscp {
   forwarding-class expedited-forwarding {
       loss-priority low code-points 101110;
   }
}
dscp backbone_dscp {
   forwarding-class expedited-forwarding {
       loss-priority low code-points 101110;
   }
}
exp backbone_exp {
   forwarding-class expedited-forwarding {
       loss-priority low code-points 100;
   }
}
exp ss7_backbone {
   forwarding-class expedited-forwarding {
       loss-priority low code-points 101;

Then you are going to need to define "schedulers", where you basically
"limit the participation of a group to a forwarding class". For
example, a snip from [edit class-of-service schedulers] :

backbone_ef {
   transmit-rate percent 40;
   priority high;
}
backbone_be {
   transmit-rate percent 55;
   priority low;

backbone_nc {
   transmit-rate percent 5;
   priority high;

 There, you limit %40 of the traffic for "expedited-forwarding" queue
with high priority, which is typically your important traffic, %5 of
the traffic for network-control (which might be eighter your telnet
access or ospf/bgp etc. negociation) with high priority as well and
put the rest (%55) to the best-effort queue with low priority this
time.

 Later on, you'll want some "scheduler-maps", where you really "map
the schedulers". Let's go on with the previous examples:

access {
   forwarding-class best-effort scheduler access_be; ## you associate
scheduler "access-be" with the best effort queue.
   forwarding-class expedited-forwarding scheduler access_ef;
}
backbone {
   forwarding-class best-effort scheduler backbone_be;
   forwarding-class expedited-forwarding scheduler backbone_ef;
   forwarding-class network-control scheduler backbone_nc;

 Once you're done with your queueing strategy and queues, you can
define your interfaces. Let's assume ds-0/0/0 is a customer connection
and e3-1/0/0 is a backbone uplink. So you might have:

 ds-0/0/0 {
   scheduler-map backbone;
       classifiers {
           dscp access_dscp;
       }
}
 e3-5/2/0 {
   scheduler-map backbone;
   unit 0 {
       classifiers {
           dscp backbone_dscp;
           exp backbone_exp;
       }
   }
}

 Now you're done.

 Hope this helps,

On 6/10/05, Lukasz Trabinski <lukaszt at atm.com.pl> wrote:
> Hello
> 
> Where i can find simple example of CoS configuration. I want to prefer one
> or more IP addresses on one ATM/OC2 interface. Documentation from
> www.juniper.net is a little bit insufficient/hard for me :(
> 
> Thank You.
> 
> --
> Lukasz Trabinski
> 
> _______________________________________________
> juniper-nsp mailing list juniper-nsp at puck.nether.net
> http://puck.nether.net/mailman/listinfo/juniper-nsp
> 


-- 

-erdem