This command creates a text description stored in the configuration file for a configuration context.
The description command associates a text string with a configuration context to help identify the context in the configuration file.
The no form of this command removes any description string from the context.
No description is associated with the configuration context.
This command enables the context to modify the QoS default shared-queue policy.
This command specifies the forwarding class name. The forwarding class name represents an egress queue. The fc fc-name represents a CLI parent node that contains sub-commands or parameters describing the egress characteristics of the queue and the marking criteria of packets flowing through it. The fc command overrides the default parameters for that forwarding class defined in the network default policy policy-id 1.
See Default Shared Queue Policy Values for undefined forwarding class values.
This command configures the broadcast forwarding type queue mapping for fc fc-name. The specified queue-id must exist within the policy as a multipoint queue before the mapping can be made. When the forwarding class mapping is executed, all broadcast traffic on a SAP using this policy will be forwarded using the queue-id.
The broadcast forwarding type usually tracks the multicast forwarding type definition. This command overrides that default behavior.
The no form of this command sets the broadcast forwarding type queue-id back to the default of tracking the multicast forwarding type queue mapping.
This command configures the multicast forwarding type queue mapping for fc fc-name. The specified queue-id must exist within the policy as a multipoint queue before the mapping can be made. When the forwarding class mapping is executed, all multicast traffic on a SAP using this policy is forwarded using the queue-id.
The multicast forwarding type includes the unknown unicast forwarding type and the broadcast forwarding type unless each is explicitly defined to a different multipoint queue. When the unknown and broadcast forwarding types are left as default, they will track the defined queue for the multicast forwarding type.
The no form of this command sets the multicast forwarding type queue-id back to the default queue for the forwarding class. If the broadcast and unknown forwarding types were not explicitly defined to a multipoint queue, they will also be set back to the default multipoint queue (queue 11).
This command overrides the default unicast forwarding type queue mapping for fc fc-name. The specified queue-id must exist within the policy as a non-multipoint queue before the mapping can be made. When the forwarding class mapping is executed, all unicast traffic (this includes all traffic, even broadcast and multicast for services) on a SAP using this policy is forwarded using the queue-id.
The no form of this command sets the unicast (point-to-point) queue-id back to the default queue for the forwarding class (queue 1).
This command configures the unknown unicast forwarding type queue mapping for fc fc-name. The specified queue-id must exist within the policy as a multipoint queue before the mapping can be made. When the forwarding class mapping is executed, all unknown traffic on a SAP using this policy is forwarded using the queue-id.
The unknown forwarding type usually tracks the multicast forwarding type definition. This command overrides that default behavior.
The no form of this command sets the unknown forwarding type queue-id back to the default of tracking the multicast forwarding type queue mapping.
This command creates the context to configure a shared queue QoS policy queue.
Explicit definition of an ingress queue’s type is supported. A single ingress queue allows support for multiple forwarding classes. The default behavior automatically chooses the expedited or best effort nature of the queue based on the forwarding classes mapped to it. As long as all forwarding classes mapped to the queue are expedited (nc, ef, h1, or h2), the queue is treated as an expedited queue by the hardware schedulers. When any best effort forwarding classes are mapped to the queue (be, af, l1, or l2), the queue is treated as best effort by the hardware schedulers. The queue type can be overridden within the policy.
On the 7450 ESS, the expedited hardware schedulers are used to enforce expedited access to internal switch fabric destinations. The hardware status of the queue must be defined at the time of queue creation within the policy.
expedite — This keyword ensures that the queue is treated in an expedited manner independent of the forwarding classes mapped to the queue.
best-effort — This keyword ensures that the queue is treated in a non-expedited manner independent of the forwarding classes mapped to the queue.
auto-expedite — This keyword allows the system to auto-define the way the queue is serviced by the hardware. When auto-expedite is defined on the queue, the queue is treated in an expedited manner when all forwarding classes mapped to the queue are configured as expedited types nc, ef, h1, or h2. When a single non-expedited forwarding class is mapped to the queue (be, af, l1, and l2) the queue automatically falls back to non-expedited status.
A queue must be created as multipoint. The multipoint designator cannot be defined after the queue is created. If an attempt is made to modify the command to include the multipoint keyword, an error is generated and the command will not execute.
The multipoint keyword can be entered in the command line on a preexisting multipoint queue to edit queue-id parameters.
The Committed Burst Size (cbs) command specifies the relative amount of reserved buffers for a specific ingress shared queue. The value is entered as a percentage.
The CBS for a queue is used to determine whether it has exhausted its reserved buffers while enqueuing packets. When the queue has exceeded the amount of buffers considered in reserve for this queue, it must contend with other queues for the available shared buffer space within the buffer pool.
The resultant CBS size can be larger than the MBS. This will result in a portion of the CBS for the queue being unused and should be avoided.
The queue CBS defaults are listed in Table 96.
Queue | Default CBS |
1 | 1 |
2 | 3 |
3 | 10 |
4 | 3 |
5 | 10 |
6 | 10 |
7 | 3 |
8 | 3 |
9 | 1 |
10 | 1 |
11 | 1 |
12 | 1 |
13 | 1 |
14 | 1 |
15 | 1 |
16 | 1 |
This command enters the context to configure queue drop tail parameters.
This command enters the context to configure the queue low drop-tail parameters. The low drop-tail defines the queue depth beyond which out-of-profile packets will not be accepted into the queue and will be discarded.
This command configures the ingress shared queue low drop tail as a percentage reduction from the MBS of the queue. For example, if a queue has an MBS of 600 kbytes and percent-reduction-from-mbs is configured to be 30% for the low drop tail, then the low drop tail will be at 420 kbytes and out-of-profile packets will not be accepted into the queue if its depth is greater than this value and will be discarded.
percent-reduction-from-mbs 10
This command specifies the relative amount of the buffer pool space for the maximum buffers for a specific ingress shared queue.
The MBS value is used by a queue to determine whether it has exhausted its total allowed buffers while enqueuing packets. When the queue has exceeded its maximum amount of buffers, all packets are discarded until the queue transmits a packet. A queue that has not exceeded its MBS size is not guaranteed that a buffer will be available when needed. Setting proper CBS parameters and controlling CBS oversubscription is one major safeguard against queue starvation (when a queue does not receive its fair share of buffers).
The MBS size can sometimes be smaller than the CBS. This will result in a portion of the CBS for the queue to be unused and should be avoided.
The queue MBS defaults are listed in Table 97.
Queue | Default MBS |
1 | 50 |
2 | 50 |
3 | 50 |
4 | 25 |
5 | 50 |
6 | 50 |
7 | 25 |
8 | 25 |
9 | 50 |
10 | 50 |
11 | 50 |
12 | 25 |
13 | 50 |
14 | 50 |
15 | 25 |
16 | 25 |
This command defines the administrative PIR, the administrative CIR, and the administrative FIR parameters for the queue.
The PIR defines the percentage that the queue can transmit packets through the switch fabric (for ingress queues). Defining a PIR does not necessarily guarantee that the queue can transmit at the intended rate. The actual rate sustained by the queue can be limited by over-subscription factors or available bandwidth.
The CIR defines the percentage at which the system prioritizes the queue over other queues competing for the same bandwidth.
The rate command can be executed at any time, altering the PIR, CIR, and FIR for the queue created with the queue-id.
The command outputs shown in this section are examples only; actual displays may differ depending on supported functionality and user configuration.
This command displays shared-queue policy information.
The following output is an example of shared-queue QoS policy information, and Table 98 describes shared-queue QoS policy output fields.
Label | Description |
Policy | The ID that uniquely identifies the policy. |
Description | A text string that helps identify the policy’s context in the configuration file. |