Configuring The Network Diameter Of A Switched Network; Configuring Timers Of Mstp - HP 5820X series Configuration Manual

Configuring the network diameter of a switched network

Any two terminal devices in a switched network are interconnected through a specific path composed of
a series of devices. The network diameter is the number of devices on the path composed of the most
devices. The network diameter is a parameter that indicates the network size. A bigger network diameter
indicates a larger network size.
Make this configuration on the root bridge only.
To configure the network diameter of a switched network:
To do...
1. Enter system view
2. Configure the network
diameter of the switched
network
After specifying the current device as the root bridge or a secondary root bridge, you cannot change the
priority of the device.
Alternatively, you can also configure the current device as the root bridge by setting the priority of the
device to 0. For the device priority configuration, see

Configuring timers of MSTP

STP calculation involves the following timing parameters.
Forward delay: Determines the time interval of state transition. To prevent temporary loops, a port
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must go through an intermediate state, the learning state, before it transitions from the discarding
state to the forwarding state, and must wait a certain period of time (forward delay) before it
transitions from one state to another to keep synchronized with the remote device during state
transition.
Hello time: Used to detect link failures. STP sends configuration BPDUs at the interval of hello time. If
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a device fails to receive configuration BPDUs within the hello time, a new spanning tree calculation
process will be triggered because of configuration BPDU timeout.
Max age: Used to detect configuration BPDU timeout. In the CIST, the device determines whether a
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configuration BPDU received on a port has expired based on the max age timer. If a port receives a
configuration BPDU that has expired, that MSTI must be re-calculated. The max age is meaningless
for MSTIs.
To avoid frequent network changes, the settings of the hello time, forward delay and max age timers must
meet the following formulas:
2 × (forward delay – 1 second) ƒ max age
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Max age ƒ 2 × (hello time + 1 second)
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HP does not recommend that you set the timers manually. Instead, you can use the stp bridge-diameter
command to set the network diameter, and let the network automatically adjust the three timers according
to the network size. When the network diameter is the default value, the three timers are also set to their
defaults.
Make this configuration on the common root bridge only, and then this configuration applies to all
devices on the entire switched network.
Use the command...
system-view
stp bridge-diameter diameter
"Configuring the priority of a
75
Remarks
—
Required
7 by default
device."