4 Web-based Switch Configuration
D-Link DGS-2000 Series Ethernet Switch User Manual
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By default, Rapid Spanning Tree is disabled. If enabled, the Switch will listen for BPDU packets and its
accompanying Hello packet. BPDU packets are sent even if a BPDU packet was not received. Therefore,
each link between bridges is sensitive to the status of the link. Ultimately this difference results in faster
detection of failed links, and thus faster topology adjustment.
By default Multiple Spanning Tree is enabled. It will tag BPDU packets to receiving devices and distinguish
spanning tree instances, spanning tree regions and the VLANs associated with them.
After enabling STP, setting the STP Global Setting includes the following options:
Figure 4.85 - Configuration > Spanning Tree > STP Bridge Global Settings
STP State:
Specify the Spanning Tree Protocol to be Enabled or Disabled.
STP Version:
Choose MSTP, RSTP or STP Compatible. The default setting is MSTP.
Bridge Priority:
This value between 0 and 61410 specifies the priority for forwarding packets: the lower the
value, the higher the priority. The default is
32768
.
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
6.
Maximum Age (6-40 sec):
This value 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 the Switch has the lowest Bridge Identifier, it will become the
Root Bridge. A time interval may be chosen between
6
and
40
seconds. The default value is
20
. (Max Age
has to have a value bigger than Hello Time)
Hello Time (1-10 sec):
The user may set the time interval between transmissions of configuration messages
by the root device, thus stating that the Switch is still functioning. The default is
2
seconds.
Forward Delay (4-30 sec):
This sets the maximum amount of time that the root device will wait before
changing states. The default is
15
seconds.
Forwarding BPDU:
Bridges use Bridge Protocol Data Units (BPDU) to provide spanning tree information.
STP BPDUs filtering is useful when a bridge interconnects two regions; each region needing a separate
spanning tree. BPDU filtering functions only when STP is disabled either globally or on a single interface.
Enabled -
BPDU filtering is enabled on the port.
Disabled -
BPDU forwarding is enabled on the port (if STP is disabled).
Maximum Hop (6-40 secs):
Specifies 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
