Information About Mstp; Mstp Configuration - Cisco Catalyst 2960-XR Configuration Manual

Configuring Multiple Spanning-Tree Protocol
Table 8: PVST+, MSTP, and Rapid PVST+ Interoperability and Compatibility
PVST+
MSTP
Rapid PVST+
Related Topics
Specifying the MST Region Configuration and Enabling MSTP, on page 59
MSTP Configuration Guidelines, on page 44
Multiple Spanning-Tree Regions, on page 45
Configuring the Root Switch, on page 62
Root Switch, on page 44
Specifying the MST Region Configuration and Enabling MSTP, on page 59

Information About MSTP

MSTP Configuration

MSTP, which uses RSTP for rapid convergence, enables multiple VLANs to be grouped into and mapped to
the same spanning-tree instance, reducing the number of spanning-tree instances needed to support a large
number of VLANs. The MSTP provides for multiple forwarding paths for data traffic, enables load-balancing,
and reduces the number of spanning-tree instances required to support a large number of VLANs. It improves
the fault tolerance of the network because a failure in one instance (forwarding path) does not affect other
instances (forwarding paths).
The multiple spanning-tree (MST) implementation is based on the IEEE 802.1s standard.
Note
The most common initial deployment of MSTP is in the backbone and distribution layers of a Layer 2 switched
network. This deployment provides the highly available network required in a service-provider environment.
When the switch is in the MST mode, the RSTP, which is based on IEEE 802.1w, is automatically enabled.
The RSTP provides rapid convergence of the spanning tree through explicit handshaking that eliminates the
IEEE 802.1D forwarding delay and quickly transitions root ports and designated ports to the forwarding state.
Both MSTP and RSTP improve the spanning-tree operation and maintain backward compatibility with
equipment that is based on the (original) IEEE 802.1D spanning tree, with existing Cisco-proprietary Multiple
Instance STP (MISTP), and with existing Cisco PVST+ and rapid per-VLAN spanning-tree plus (Rapid
PVST+).
A switch stack appears as a single spanning-tree node to the rest of the network, and all stack members use
the same switch ID.
OL-29424-01
PVST+ MSTP
Yes Yes (with restrictions)
Yes (with restrictions) Yes
Yes (reverts to PVST+) Yes (reverts to PVST+)
Catalyst 2960-XR Switch Layer 2 Configuration Guide, Cisco IOS Release 15.0(2)EX1
Information About MSTP
Rapid PVST+
Yes (reverts to PVST+)
Yes (reverts to PVST+)
Yes
43