D-Link xStack DGS-3400 Series Reference Manual page 213

x Stack
STP Version
Hello Time (1 - 10 sec)
Max Age (6 - 40 sec)
Forward Delay (4-30
sec)
Max Hops (1-40)
TX Hold Count (1-10)
Forwarding BPDU
Loopback Detection
LBD Recover Time
NNI BPDU Address
Click Apply to implement the changes.
®
DGS-3400 Series Layer 2 Gigabit Ethernet M anaged Sw itch
Use the pull-down menu to choose the desired version of STP:
STP compatible – 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.
The Hello Time can be set from 1 to 10 seconds. If the inputted Hello Time is more than 2,
the Hello Time is also 2. 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.
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.
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.
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. If the Max Hops is less than 6,
the Max Hops is 6.
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.
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.
When enabled, the Switch will temporarily block STP switch-wide when a BPDU packet
has looped back. If the Switch detects its own BPDU packet coming back, it signifies a loop
on the network – STP is automatically blocked and an alert is sent to the administrator. The
default is Enabled.
Time allowed (in seconds) for recovery when an STP Loopback is detected. After the timer
has expired the Switch checks for an STP loopback, if no loopback detected, STP is
resumed. Entering 0 will disable LBD recovery.
This field is used to configure the NNI port address.
dot1d – Specifies STP's BPDU MAC address of NNI port using the definition of 802.1d.
dot1ad – Specifies STP's PDU MAC address of NNI port using the definition of 802.1ad.
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