HP FlexNetwork NJ5000 User Manual page 174

Item
Max Hops
Path Cost Standard
Bridge Diameter
Timers
Instance (Instance ID,
Root Type, and Bridge
Priority)
tc-protection
tc-protection threshold
Description
connected with a device running STP.
Sets the maximum number of hops in an MST region to restrict the region
size.
The setting can take effect only when it is configured on the regional root
bridge.
Specifies the standard for path cost calculation. It can be Legacy, IEEE
802.1D-1998, or IEEE 802.1T.
Any two stations in a switched network are interconnected through a specific
path composed of a series of devices. The bridge diameter (or the network
diameter) is the number of devices on the path composed of the most
devices.
After you set the network diameter, you cannot set the timers. Instead, the
device automatically calculates the forward delay, hello time, and max age.
When you configure the bridge diameter, follow these guidelines:
•
The configured network diameter is effective on CIST only, not on
MSTIs.
•
The bridge diameter cannot be configured together with the timers.
Configure the timers:
•
Forward Delay—Set the delay for the root and designated ports to
transit to the forwarding state.
•
Hello Time—Set the interval at which the device sends hello packets to
the surrounding devices to make sure the paths are fault-free.
•
Max Age—Set the maximum length of time a configuration BPDU can
be held by the device.
When you configure timers, follow these guidelines:
•
The settings of hello time, forward delay and max age must meet a
certain formula. Otherwise, the network topology will not be stable.
Hewlett Packard Enterprise recommends you to set the network
diameter and then have the device automatically calculate the forward
delay, hello time, and max age.
•
The bridge diameter cannot be configured together with the timers.
Sets the role of the device in the MSTI or the bridge priority of the device,
which is one of the factors deciding whether the device can be elected as the
root bridge.
Role of the device in the MSTI:
•
Not Set—Not set (you can set the bridge priority of the device when
selecting this role)
•
Primary—Configure the device as the root bridge (you cannot set the
bridge priority of the device when selecting this role)
•
Secondary—Configure the device as a secondary root bridge (you
cannot set the bridge priority of the device when selecting this role).
Selects whether to enable TC-BPDU guard.
When receiving topology change (TC) BPDUs, the device flushes its
forwarding address entries. If someone forges TC-BPDUs to attack the
device, the device will receive a large number of TC-BPDUs within a short
time and frequently flushes its forwarding address entries. This affects
network stability.
With the TC-BPDU guard function, you can prevent frequent flushing of
forwarding address entries.
Hewlett Packard Enterprise recommends not disabling this function.
Sets the maximum number of immediate forwarding address entry flushes the
device can perform within a certain period of time after receiving the first
TC-BPDU.
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