Technical data

20 Brocade 6910 Ethernet Access Switch Diagnostic Guide
53-1002348-02
Spanning Tree Protocol and derivatives
MAC address learning show commands
The following command displays information about the MAC address table.
show mac-address-table
Syntax: show mac-address-table
This command displays the MAC address table, which contains MAC addresses learned from other
devices. This table does not contain the MAC addresses of the Brocade device ports.
Console# show mac-address-table
Total entry in system: 3
Interface MAC Address VLAN Type Life Time
--------- ----------------- ---- -------- -----------------
CPU 70-72-CF-32-DD-FD 1 CPU Delete on Reset
Eth 1/ 1 00-01-EC-F8-D8-D6 1 Learn Delete on Timeout
Eth 1/ 1 00-E0-29-94-34-64 1 Learn Delete on Timeout
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,