Chapter 4. Web Configuration & Operation
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CHAPTER 4
WEB OPERATION & CONFIGURATION
most of its basic operation characteristics. This essentially creates a cascading effect away from the root bridge where
each designated bridge proposes to its neighbors to determine if it can make a rapid transition. This is one of the
major elements which allows RSTP to achieve faster convergence times than STP.
The other extension of RSTP is IEEE 802.1s Multiple Spanning Tree protocol (MSTP) that allows different VLANs to
travel along separate instances of spanning tree. Unlike STP and RSTP, MSTP eliminates the needs for having different
STP for each VLAN. Therefore, in a large networking environment that employs many VLANs, MSTP can be more useful
than legacy STP.
4.7.3.1 Bridge Settings
Basic Settings
Protocol Version:
Select the appropriate spanning tree protocol. Protocol versions provided include “STP”, “RSTP”,
and “MSTP”.
Bridge Priority:
Each switch has a relative priority and cost that is used to decide what the shortest path is to forward
a packet. The lowest cost path (lowest numeric value) has a higher priority and is always used unless it is down. If you
have multiple bridges and interfaces then you need to adjust the priorities to achieve optimized performance. For
MSTP operation, this is the priority of the CIST. Otherwise, this is the priority of the STP/RSTP bridge.
Forward Delay:
Fort STP bridges, the Forward Delay is the time spent in each Listening and Learning state before the
Forwarding state is entered. This delay occurs when a new bridge comes onto a network. Valid values are 4-30
seconds.
Max Age:
If another switch in the spanning tree does not send out a hello packet for a period of time, it is considered
to be disconnected. Valid values are 6 to 40 seconds, and Max Age values must be smaller than or equal to (Forward
Delay-1)*2.
Maximum Hop Count:
The maximum number of hops allowed for MST region before a BPDU is discarded. Each bridge
decrements the hop count by one before passing on the BPDU. When the hop count reaches zero, the BPDU is
discarded. The default hop count is 20. The allowed range is 6-40.
Transmit Hold Count:
The number of BPDU sent by a bridge port per second. When exceeded, transmission of the
next BPDU will be delayed. By default, it is set to 6. The allowed transmit hold count is 1 to 10. Please note that
increasing this value might have a significant impact on CPU utilization and decreasing this value might slow down
convergence. It is recommended to remain Transmit Hold Count to the default setting.
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