Spanning Tree Algorithm
105
Instruction Manual - NXA-ENET8-POE+
NOTE:
Region Revision and Region Name and are both required to uniquely identify an MST region.
When the Switch Becomes Root
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 reconverge. 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.)
• Default: 20
• Minimum: The higher of 6 or [2 x (Hello Time + 1)]
• Maximum: The lower of 40 or [2 x (Forward Delay - 1)]
Forward Delay
The maximum time (in seconds) this device will wait before changing states (i.e., discarding to
learning to forwarding). This delay is required because every device must receive information
about topology changes before it starts to forward frames. In addition, each port needs time to
listen for conflicting information that would make it return to a discarding state; otherwise,
temporary data loops might result.
• Default: 15
• Minimum: The higher of 4 or [(Max. Message Age / 2) + 1]
• Maximum: 30
RSTP does not depend on the forward delay timer in most cases. It is able to confirm that a port
can transition to the forwarding state without having to rely on any timer configuration. To achieve
fast convergence, RSTP relies on the use of edge ports, and automatic detection of point-to-point
link types, both of which allow a port to directly transition to the forwarding state.
Configuration Settings for MSTP
Max Instance Numbers
The maximum number of MSTP instances to which this switch can be assigned.
Configuration Digest
An MD5 signature key that contains the VLAN ID to MST ID mapping table. In other words, this key
is a mapping of all VLANs to the CIST.
Region Revision
The revision for this MSTI. (Range: 0-65535; Default: 0).
Region Revision is required to uniquely
identify an MST region.
Region Name
The name for this MSTI. (Maximum length: 32 characters; Default: switch's MAC address).
Region
Name is required to uniquely identify an MST region.
Max Hop Count
The maximum number of hops allowed in the MST region before a BPDU is discarded. (Range:
1-40; Default: 20
Spanning Tree - STA Options