Preempt Delay - Cisco ASR 9000 Series Reference Manual

preempt delay

preempt delay
To enable topology control and set the preempt delay on startup, use the preempt delay command in MSTAG,
REPAG, PVSTAG or PVRSTAG configuration mode.
preempt delay {for time {seconds| minutes| hours}| until hh:mm:ss}
Syntax Description
for
until
Command Default
Startup topology control is disabled.
Command Modes
MSTAG configuration, REPAG configuration, PVSTAG configuration, PVRSTAG configuration
Command History
Release
Release 3.7.1
Release 4.0.0
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes appropriate task
IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator
for assistance.
This command enables startup topology control for Access Gateway. By default, when an interface comes
up, Access Gateway starts sending STP BPDUs immediately based on the configured values. This could cause
the devices in the access network to immediately start directing traffic to this device. However, the data plane
may not yet be ready to forward packets to the core or aggregation network. When a preempt delay is
configured, alternative values are sent in the BPDUs for the specified time. These alternative values must be
configured using the startup-value option, and can be set so as to cause the access devices not to use this
link unless it is the only one available.
For more information on preempt delay, refer to the Implementing Multiple Spanning Tree Protocol module
in the Cisco ASR 9000 Series Aggregation Services Router L2VPN and Ethernet Services Configuration Guide.
Task ID
Task ID
ethernet-services (PVSTAG and PVRSTAG only)
Cisco ASR 9000 Series Aggregation Services Router VPN and Ethernet Services Command Reference, Release
6.1.x
560
Specifies length of time to delay preempting for in seconds, minutes or hours.
Specifies time to delay preempting until the mentioned interval (24-hour hh:mm:ss).
Modification
This command was introduced.
This command was supported in the PVSTAG and PVRSTAG
configuration modes.
Multiple Spanning Tree Protocol Commands
Operations
read, write