User`s manual

40 Asanté IntraCore 36000 Series
Multiple Spanning Tree Protocol
To allow multiple spanning trees to operate over the network, you must configure a related set of bridges
with the same MSTP configuration, allowing them to participate in a specific set of spanning tree instances.
• A spanning tree instance can exist only on bridges that have compatible VLAN instance assignments.
• Be careful when switching between spanning tree modes. Changing modes stops all spanning-tree
instances for the previous mode and restarts the system in the new mode, temporarily disrupting user
traffic.
3.1.2 Spanning Tree Basic Configuration
This section describes the basic configuration for STP, including the global settings and root device
configuration,
Global Settings
Spanning Tree State – Enables/disables STA on this switch. (Default: Enabled)
Spanning Tree Type – Specifies the type of spanning tree used on this switch:
• STP: Spanning Tree Protocol (IEEE 802.1D); For example, when this option is selected, the switch will
use RSTP set to STP forced compatibility mode).
• RSTP: Rapid Spanning Tree (IEEE 802.1w)
• MSTP: Multiple Spanning Tree (IEEE 802.1s); MSTP is the default.
Priority – Bridge priority is used in selecting the root device, root port, and designated port. The device with
the highest priority becomes the STA root device. If all devices have the same priority, the device with the
lowest MAC address will then become the root device. (Note that lower numeric values indicate higher
priority.)
• Default: 32768
• Range: 0-61440, in steps of 4096
• Options: 0, 4096, 8192, 12288, 16384, 20480, 24576, 28672, 32768, 36864, 40960, 45056, 49152,
53248, 57344, 61440
Root Device Configuration
Hello Time – Interval (in seconds) at which the root device transmits a configuration message.
• Default: 2
• Minimum: 1
• Maximum: The lower of 10 or [(Max. Message Age / 2) -1]
Maximum Age – The maximum time (in seconds) a device can wait without receiving a configuration
message before attempting to reconfigure. All device ports (except for designated ports) should receive
configuration messages at regular intervals. Any port that ages out STA information (provided in the last
configuration message) becomes the designated port for the attached LAN. If it is a root port, a new root port
is selected from among the device ports attached to the network. (References to “ports” in this section mean
“interfaces,” which includes both ports and trunks.)