Brocade 6910 Ethernet Access Switch Diagnostic Guide (Supporting R2.2.0.0) - Manual (Page 35)

Brocade 6910 Ethernet Access Switch Diagnostic Guide 25
53-1002653-01
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DRAFT: BROCADE CONFIDENTIAL
Spanning Tree Protocol and derivatives
00-E0-0C-10-90-00 1 1/1 0 0 0 1 13348
4 records
The following command displays detailed information about the VLAN mapping table.
Console#debug hardware dev-amtrdrv vidx-table
vidx vlan MAC Used
---- ---- ----------------- ----
0 1 01-00-5E-01-01-01 1
1 5 01-00-5E-02-01-01 1
2 5 01-00-5E-02-01-02 1
3 5 01-00-5E-02-01-03 1
4 5 01-00-5E-02-01-04 1
5 5 01-00-5E-02-01-05 1
Spanning Tree Protocol and derivatives
The following sections describe diagnostic procedures for Spanning Tree Protocol (STP) and STP
derivatives, including RSTP and MSTP.
NOTE
Layer 2 protocols such as STP and RSTP can be enabled on port-based VLANs, but cannot be
enabled or disabled on protocol-based VLANs.
STP
A control protocol, such as Spanning Tree Protocol (STP), can block one or more ports in a
protocol-based VLAN that uses a virtual routing interface to route to other VLANs. For IP VLANs and
IP subnet VLANs, even though some of the physical ports of the virtual routing interface are
blocked, the virtual routing interface can still route as long as at least one port in the
protocol-based VLAN is not blocked by STP.
RSTP
Rapid Spanning Tree Protocol (RSTP) provides rapid traffic reconvergence for point-to-point links
within a few milliseconds (less than 500 milliseconds) following the failure of a bridge or bridge
port. This reconvergence occurs more rapidly than that provided by STP because convergence in
RSTP bridges is based on the explicit handshakes between designated ports and their connected
root ports rather than on timer values.
MSTP
With Multiple Spanning Tree Protocol (MSTP), the entire network runs a common instance of RSTP.
Within the common instance, one or more VLANs can be individually configured into distinct
regions. The entire network runs the Common Spanning Tree (CST) instance and the regions run a
local instance, or Internal Spanning Tree (IST). Because the CST treats each IST as a single bridge,
ports are blocked to prevent loops that might occur within an IST and also throughout the CST. In
addition, MSTP can co-exist with individual devices running STP or RSTP in the Common and
Internal Spanning Tree instance (CIST). With the exception of the provisions for multiple instances,
MSTP operates exactly like RSTP.