Dell N1100-ON, Reference Manual

Page: 746 / 2332

Layer 2 Switching Commands
746
console(config-if-4/0/1)#spanning-tree auto-portfast
spanning-tree backbonefast
Use the spanning-tree backbonefast command to enable the detection of
indirect link failures and accelerate spanning tree convergence on
STP-PV/RSTP-PV configured switches using Indirect Link Rapid
Convergence (IRC). IRC accelerates finding an alternative path when an
indirect link to the root port goes down. Use the no form of the command to
disable the IRC feature.
Syntax
spanning-tree backbonefast
no spanning-tree backbonefast
Default Configuration
This command has no default configuration.
Command Modes
Global Configuration Mode
User Guidelines
IRC can be configured even if the switch is configured for MST(RSTP) or
RSTP-PV mode. It only has an effect when the switch is configured for
STP-PV mode.
If an IRC-enabled switch receives an inferior BPDU from its designated
switch on a root or blocked port, it sets the maximum aging time on the
interfaces on which it received the inferior BPDU if there are alternative
(blocked) paths to the designated switch. This allows a blocked port to
immediately move to the listening state where the port can be transitioned to
the forwarding state in the normal manner.
Example
console(config)#spanning-tree backbonefast