D-Link DGS-3627G Product Manual - Page 152

xStack® DGS-3600 Series Layer 3 Managed Gigabit Ethernet Switch STP Version Use the pull-down menu to choose STP compatible, RSTP, and MSTP. RSTP is the default. Hello Time (1-10 sec) The Hello Time can be set from 1 to 10 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. Max Age (6-40 sec) 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 (4-30 The Forward Delay can be from 4 to 30 seconds. Any port on the Switch spends this time in sec) the listening state while moving from the blocking state to the forwarding state. Max Hops (1-40) 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 40. The default is 20. TX Hold Count (1-10) Used to set the maximum number of Hello packets transmitted per interval. The count can be specified from 1 to 10. The default is 3. Forwarding BPDU Loopback Detection LBD Recover Time () or 60-1000000) NNI BPDU Address This field can be Enabled or Disabled. When Enabled, it allows the forwarding of STP BPDU packets from other network devices. The default is Disabled. This feature is used to temporarily shutdown a port on the Switch when a BPDU packet has been looped back to the switch. When the Switch detects its own BPDU packet coming back, it signifies a loop on the network. STP will automatically be blocked and an alert will be sent to the administrator. The LBD STP port will restart (change to discarding state) when the LBD Recover Time times out. The Loopback Detection function will only be implemented on one port at a time. The user may enable or disable this function using the pull-down menu. The default is Enabled. This field will set the time the STP port will wait before recovering the STP state set. 0 will denote that the LBD will never time out or restart until the administrator personally changes it. The user may also set a time between 60 and 1000000 seconds. The default is 60 seconds. Use the drop-down menu to choose Dot1d or Dot1ad. NOTE: The Loopback Detection function can only be implemented on the Switch if it is configured both on the STP Global Settings window, and on the STP Port Settings window. Enabling this feature through only one of these windows will not fully enable the Loopback Detection function. Click Apply to implement changes made. MST Configuration Identification The MST Configuration Identification window allows the user to configure a MSTI instance on the Switch. These settings will uniquely identify a multiple spanning tree instance set on the Switch. The Switch initially possesses one CIST or Common Internal Spanning Tree of which the user may modify the parameters for but cannot change the MSTI ID for, and cannot be deleted. To view this window, click L2 Features > Spanning Tree > MST Configuration Identification, as shown below: 136