Identifying PICs Restricted to Four Queues on T Series Core Routers
Some Juniper Networks T Series Core Router PICs support up to 16 forwarding classes and are restricted to 4 queues. Contact Juniper Networks customer support for a current list of T Series router PICs that are restricted to four queues.
To determine how many queues an interface supports, you can
check the CoS queues output field of the show
interfaces interface-name extensive command:
user@host> show interfaces so-1/0/0 extensive CoS queues: 8 supported
By default, for T Series router PICs that are restricted to four queues, the router overrides the global configuration based on the following formula:
Qr = Qd mod Rmax
Qr is the queue number assigned if the PIC is restricted
to four queues.
Qd is the queue number that would have been mapped
if this PIC were not restricted.
Rmax is the maximum number of restricted queues available.
Currently, this is four.
For example, assume you map the forwarding class ef to queue 6. For a PIC restricted to four queues, the queue number
for forwarding class ef is Qr = 6 mod 4 =
2.
To determine which queue is assigned to a forwarding class,
use the show class-of-service forwarding-class command
from the top level of the CLI. The output shows queue assignments
for both global queue mappings and restricted queue mappings:
user@host> show class-of-service forwarding-class Forwarding class Queue Restricted Queue Fabric priority be 0 2 low ef 1 2 low assured-forwarding 2 2 low network-control 3 3 low
For T Series router PICs restricted to four queues, you
can override the formula-derived queue assignment by including the restricted-queues statement at the [edit class-of-service] hierarchy level. For example:
You can configure up to 16 forwarding classes. The output
queue number can be from 0 through 3. Therefore, for PICs
restricted to four queues, you can map multiple forwarding classes
to single queues. If you map multiple forwarding classes to a queue,
the multiple forwarding classes must refer to the same scheduler.
This requirement applies to all PICs. The class name you configure
at the [edit class-of-service restricted-queues] hierarchy
level must be either a default forwarding class name or a forwarding
class you configure at the [edit class-of-service forwarding-classes] hierarchy level.