Document No. 10-300077, Issue 2 7-9
Configuring Rapid Spanning Tree
CLI Command Use the following CLI commands to configure global Spanning Tree
options:
■To set the type of spanning tree that you want the switch to run,
(configure)# set spantree config {ieee | per- vlan | dual-layer
| disable}
■To set the version of spanning tree that you want the switch to run,
(configure)# set spantree version {common-spanni ng-tr ee |
rapid-spanning-tree}
Dual-Layer Dual-Layer spanning tree is a variation of per-VLAN
spanning tree. However, instead of using normal BPDUs
which are clear (free of VLAN tags) on clear trunks and
tagged on tagged trunks, as is the case with Per-VLAN
Spanning Tree. Dual-layer uses a proprietary BPDUs. These
proprietary BPDUs are sent to a special multicast address and
contain information about which VLAN the BPDU is
associated with.In the Dual-Layer Spanning Tree model, the
switch terminates all 802.1D Spanning Tree Domains. The
switch does not forward 802.1D BPDUs or participate in any
802.1D Spanning Tree Domains. It only participates in
Spanning Tree Domains using a proprietary BPDU, which
contains a VLAN identifier (VLAN ID). This proprietary
Spanning Tree Protocol will resolve any loops in the switch.
Legacy Bridges remain in separate Spanning Tree domains
yet Loops between the Dual Layer Domains and Legacy
domains cannot form. The Dual-Layer Spanning Tree method
is preferred when inter-operating with large legacy bridge
networks. Convergence time is reduced, and management is
simplified, by allowing the legacy bridges to remain in their
own spanning tree domain.
Disable Globally disables Spanning Tree for the entire switch.
Note: You can also disable Spanning Tree on an individual
port. See “Configuring Spanning Tree Settings for
Switch Ports” later in this chapter.
Table 7-1. Spanning Tree Information Configuration
Option Definition
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