Cisco Systems OL-7396-01 Configuring the Switch Oversubscription Factor (Catalyst 8510 MSR and

9-6
ATM Switch Router Software Configuration Guide
OL-7396-01
Chapter9 Configuring Resource Management
Configuring Global Resource Management
Displaying the ATM QoS Objective Table
To display the default QoS objective table, use the following EXEC command:
The per-service category, maximum cell transfer delay, peak-to-peak cell delay variation, and maximum
cell loss ratio objectives are displayed.
Example
The ATM QoS objective table configuration is displayed in the following example:
Switch> show atm qos-defaults
Default QoS objective table:
Max cell transfer delay (in microseconds): any cbr, any vbr-rt
Peak-to-peak cell delay variation (in microseconds): any cbr, any vbr-rt
Max cell loss ratio for CLP0 cells: any cbr, any vbr-rt, any vbr-nrt
Max cell loss ratio for CLP0+1 cells: 10**(-12) cbr, any vbr-rt, any vbr-nrt
Configuring the Switch Oversubscription Factor (Catalyst 8510 MSR and
LightStream 1010)
The switch oversubscription factor (OSF) feature on the Catalyst 8510 MSR and LightStream 1010
ATM switch routers is used in determining initial port maximum queue sizing for variable bit rate
non-real time (VBR-NRT) and available bit rate/unspecified bit rate (ABR/UBR) queues.
Note Over subscription factor configuration is only possible on switches with FC-PCQ installed.
The size of the VBR-NRT queue and ABR/UBR queues is determined by the following equations, where
the default size of the CBR and VBR-RT queues vary by interface type, as listed in Table 9- 4:
Default Size (VBR-NRT) = 0.25 * ((OSF * 2048) - DefaultSize(CBR) - DefaultSize (VBR-RT))
Default Size (ABR-UBR) = 0.75 * ((OSF * 2048) - DefaultSize(CBR) - DefaultSize (VBR-RT))
Command Purpose
show atm qos-defaults Displays the ATM QoS objective table
configuration.
Table9-4 Default CBR and VBR Determined by Interface Type
Interface Type
Default Max Size CBR
Queue
Default Max Size Type
VBR-RT Queue
SONET 256 256
DS3/E3 256 512