RuggedCom RS400 manual Cost Style, Synopsis STP 16 bit, Rstp 32 bit Default STP 16 bit

Spanning Tree

every switch that propagates the BPDU. If the maximum number of hops inside the region exceeds the configured maximum, BPDUs may be discarded due to their time-to-live information.

Cost Style

Synopsis: { STP (16 bit), RSTP (32 bit) }

Default: STP (16 bit)

This parameter selects the style of link costs to employ. STP uses 16-bit path costs based upon 1x10E9/link speed (4 for 1Gbps, 19 for 100 Mbps and 100 for 10 Mbps) whereas RSTP uses 32-bit costs based upon 2x10E13/link speed (20,000 for 1Gbps, 200,000 for 100 Mbps and 2,000,000 for 10 Mbps).Note that RSTP link costs are used only when the bridge version support is set to allow RSTP and the port does not migrate to STP.

BPDU Guard Timeout

Synopsis: 1 to 86400 s or { Until reset, Don't shutdown }

Default: Don't shutdown

The RSTP standard does not address network security. RSTP must process every received BPDU and take an appropriate action. This opens a way for an attacker to influence RSTP topology by injecting RSTP BPDUs into the network.

BPDU Guard is a feature that protects the network from BPDUs received by a port where RSTP capable devices are not expected to be attached. If a BPDU is received by a port for which 'Edge' parameter is set to 'TRUE' or RSTP is disabled, the port will be shutdown for the time period specified by this parameter.

DON'T SHUTDOWN - BPDU Guard is disabled

UNTIL RESET - port will remain shutdown until the port reset command is issued by the user

RS400 149 ROS™ v3.5