configure stpd backup-root

configure stpd stpd_name backup-root [on | off]

Description

Enables and disables the backup root feature.

Syntax Description


`stpd_name`	Specifies an STPD name on the switch.
on	Enables backup root.
off	Disable backup root.

Default

By default, the backup root feature is disabled.

Usage Guidelines

The backup root feature is used to get faster convergence when the root bridge connectivity is lost.

Backup root feature enabled bridge port should be connected to Root with point to point link. When backup root bridge loses contact with the root bridge, the backup root bridge automatically lowers its bridge priority below the priority of the lost root. This causes the backup root bridge to become the new root. If a reboot occurs, the new root will have its priority restored to the original configured value.

If the priority of the root bridge is zero and the backup root loses connectivity to the root bridge, automatic assignment of the priority value for the backup root will be the initial configured value.

This feature is activated only when connectivity with the root bridge is lost. Raising the priority on the root does not cause the backup root feature to be activated.

We recommend the following when configuring the backup root feature:

Enable the backup root feature on both the root and backup root.
Configure all bridges except the root and backup root with the maximum bridge priority value (61440 with 802.1t).
Configure the root and backup root to have the next lowest priority (57344 with 802.1t)
To help prevent the backup root feature activating due to a simple link failure rather than a bridge failure, establish multiple links between the root and backup root.
Deploy this feature carefully as it may result in suboptimal traffic forwarding paths.

Example

The following example enables the backup root feature on the STP domain r1:

configure stpd r1 backup-root on

History

This command was first available in ExtremeXOS 15.7.1.

Platform Availability

This command is available on ExtremeSwitching X435, X440-G2, X450-G2, X460-G2, X465, X590, X620, X670-G2, X690, X695, X870, 5320, 5420, and 5520 series switches.