Atm Over-Subscription-Factor Command History; Syntax Description; Usage Guidelines For The Atm Over-Subscription-Factor Command - Cisco 10000 Series Configuration Manual

ATM Virtual Circuit Oversubscription

Syntax Description

factor

atm over-subscription-factor Command History

Cisco IOS Release
Release 12.2(16)BX
Release 12.3(7)XI3
Release 12.2(28)SB
Release 12.2(31)SB2

Usage Guidelines for the atm over-subscription-factor Command

An ATM variable bit rate (VBR) VC uses the sustained cell rate (SCR) to define the VC's average
transmission rate. Therefore, use the atm over-subscription-factor command to specify the ATM VC
oversubscription, not the service-policy command.
Use the atm over-subscription-factor command for each ATM interface that you want to oversubscribe.
Because the oversubscription of VBR-nrt VCs requires resources from the entire line card, apply the
atm over-subscription-factor command on all ports of the ATM card (for example, the 4-port OC-3
ATM line card). If you enable the oversubscription on only one port, the other ports can use more
resources than they were configured to use. As a result, some ports do not receive adequate resources,
which results in VC creation failures.
Unlike other Cisco routers, the Cisco 10000 series router uses the atm oversubscribe command in
conjunction with the atm over-subscription-factor command to enable or disable oversubscription for
a particular interface or tunnel. When enabling ATM oversubscription for a particular interface or tunnel,
specify the atm over-subscription-factor command. Do not use the atm oversubscribe command to
enable oversubscription as this can cause undesirable results. Instead, leave it to the default value.
For example, the following configuration enables the oversubscription feature and configures the
interface with an oversubscription factor of 500.
Router(config)# interface atm 4/0/0
Router(config-if)# atm oversubscribe
Router(config-if)# atm over-subscription-factor 500
Router(config-if)# end
Cisco 10000 Series Router Quality of Service Configuration Guide
15-6
Specifies the amount of oversubscription. The default value is 1, which
indicates no oversubscription. Valid values are:
1 to 500 on the PRE2—Requires Cisco IOS Release 12.3(7)XI3 or later
•
releases, or Cisco IOS Release 12.2(28)SB
1 to 500 on the PRE3—Requires Cisco IOS Release 12.2(31)SB2 or
•
later releases
Description
The atm over-subscription-factor command was introduced on the PRE2
with an oversubscription factor from 1 to 50.
This command was enhanced on the PRE2 with an oversubscription factor
from 1 to 500.
This command was integrated in Cisco IOS Release 12.2(28)SB for the
PRE2.
This command was introduced on the PRE3 with an oversubscription
factor from 1 to 500.
Chapter 15 Oversubscribing Physical and Virtual Links
OL-7433-09