Alcatel-Lucent 7750 Configuration Manual page 388

Interfaces
The sum of the MBS for all queues on an ingress access port can oversubscribe the total amount of buffering
available. When congestion occurs and buffers become scarce, access to buffers is controlled by the RED
slope a packet is associated with. A queue that has not exceeded its MBS size is not guaranteed that a buffer
will be available when needed or that the packets RED slope will not force the discard of the packet. Setting
proper CBS parameters and controlling CBS oversubscription is one major safeguard to queue starvation
(when a queue does not receive its fair share of buffers). Another is properly setting the RED slope parame-
ters for the needs of services on this port or channel.
If the CBS value is larger than the MBS value, an error will occur, preventing the MBS change.
The no form of this command returns the MBS size assigned to the queue to the value.
Default default
Parameters size-in-kbytes — The size parameter is an integer expression of the maximum number of kilobytes of buff-
ering allowed for the queue. For a value of 100 kbps, enter the value 100. A value of 0 causes the queue
to discard all packets.
Values
monitor-depth
Syntax [no]monitor-depth
Context config>port>eth>access>ing>qgrp>qover>q
config>port>eth>access>egr>qgrp>qover>q
config>port>ethernet>network>egr>qgrp>qover>q
Description
This command enables queue depth monitoring for the specified queue.
The no form of the command removes queue depth monitoring for the specified queue.
rate
Syntax rate pir-rate [cir cir-rate]
no rate
Context config>port>ethernet>access>egr>qgrp>qover>q
config>port>ethernet>access>ing>qgrp>qover>q
config>port>ethernet>network>egr>qover>q
Description This command specifies the administrative Peak Information Rate (PIR) and the administrative Committed
Information Rate (CIR) parameters for the queue. The PIR defines the maximum rate that the queue can
transmit packets out an egress interface (for SAP egress queues). Defining a PIR does not necessarily guar-
antee that the queue can transmit at the intended rate. The actual rate sustained by the queue can be limited
by oversubscription factors or available egress bandwidth.
The CIR defines the rate at which the system prioritizes the queue over other queues competing for the same
bandwidth. In-profile packets are preferentially queued by the system at egress and at subsequent next hop
nodes where the packet can traverse. To be properly handled as in- or out-of-profile throughout the network,
the packets must be marked accordingly for profiling at each hop.
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7750 SR Interface Configuration Guide