D-Link DES-3550 Product Manual - Page 68

xStack® DES-3500 Series Layer 2 Stackable Fast Ethernet Managed Switch User Manual NOTE: The Hello Time cannot be longer than the Max. Age. Otherwise, a configuration error will occur. Observe the following formulas when setting the above parameters: Max. Age ≤ 2 x (Forward Delay - 1 second) Max. Age ≥ 2 x (Hello Time + 1 second) The following parameters can be set: Parameter Description STP Status Use the pull-down menu to enable or disable STP globally on the Switch. The default is Disabled. STP Version Use the pull-down menu to choose the desired version of STP to be implemented on the Switch. There are three choices: STP - Select this parameter to set the Spanning Tree Protocol (STP) globally on the switch. RSTP - Select this parameter to set the Rapid Spanning Tree Protocol (RSTP) globally on the Switch. MSTP - Select this parameter to set the Multiple Spanning Tree Protocol (MSTP) globally on the Switch. Hello Time The Hello Time can be set from 1 to 2 seconds. This is the interval between two transmissions of BPDU packets sent by the Root Bridge to tell all other switches that it is indeed the Root Bridge. This field will only appear here when STP or RSTP is selected for the STP Version. For MSTP, the Hello Time must be set on a port per port basis. See the MST Port Settings section for further details. Max Age The Max Age may be set to ensure that old information does not endlessly circulate through redundant paths in the network, preventing the effective propagation of the new information. Set by the Root Bridge, this value will aid in determining that the Switch has spanning tree configuration values consistent with other devices on the bridged LAN. If the value ages out and a BPDU has still not been received from the Root Bridge, the Switch will start sending its own BPDU to all other switches for permission to become the Root Bridge. If it turns out that your switch has the lowest Bridge Identifier, it will become the Root Bridge. The user may choose a time between 6 and 40 seconds. The default value is 20. Forward Delay The Forward Delay can be from 4 to 30 seconds. Any port on the Switch spends this time in the listening state while moving from the blocking state to the forwarding state. Max Hops Used to set the number of hops between devices in a spanning tree region before the BPDU (bridge protocol data unit) packet sent by the Switch will be discarded. Each switch on the hop count will reduce the hop count by one until the value reaches zero. The Switch will then discard the BPDU packet and the information held for the port will age out. The user may set a hop count from 1 to 20. The default is 20. TX Hold Count Used to set the maximum number of Hello packets transmitted per interval. The count can be specified from 1 to 10. The default is 6. Forwarding BPDU This field can be Enabled or Disabled. When Enabled, it allows the forwarding of STP BPDU packets from other network devices. The default is Enabled. MST Configuration Identification Configuration Name Enter an alphanumeric string of up to 32 characters to uniquely identify the MSTP region on the Switch. This Configuration Name, along with the Revision Level value will identify the MSTP region configured on the Switch. If no name is entered, the default name will be the MAC address of the device. This field is only valid when MSTP is the version of STP globally set on the Switch. Revision Level Enter a number between 0 and 65535 to identify the MSTP region. This value, along with the name will identify the MSTP region configured on the Switch. The default setting is 0. This field is only valid when MSTP is the version of STP globally set on the Switch. Click Apply to implement changes made. 53