HP 5120 EI Series User Manual

83
Link speed Port type
Path cost
IEEE 802.1d-1998 IEEE 802.1t Private standard
10 Gbps
Single port
2
2000 2
Aggregate interface
containing 2 Selected ports
1000 1
Aggregate interface
containing 3 Selected ports
666 1
Aggregate interface
containing 4 Selected ports
500 1
Configuration restrictions and guidelines
• When it calculates path cost for an aggregate interface, IEEE 802.1t takes into account the number
of Selected ports in its aggregation group, but IEEE 802.1d-1998 does not. The calculation formula
of IEEE 802.1t is: Path cost = 200,000,000/link speed (in 100 kbps), where link speed is the sum
of the link speed values of the Selected ports in the aggregation group.
• When multiple ports operate at a rate higher than 10 Gbps and the standard for default path cost
calculation is dot1d-1998 or legacy, the path cost of a single port or an aggregate interface takes
the smallest value. As a result, the forwarding path selected might not be optimal. To solve this
problem, use dot1t as the standard for default path cost calculation, or manually set the path cost
for a port (see "Configuring path costs of ports")
.
Configuration procedure
To specify a standard for the device to use when it calculates the default path cost:
Ste
p
Command Remarks
1. Enter system view.
system-view N/A
2. Specify a standard for the
device to use when it
calculates the default path
costs of its ports.
stp pathcost-standard
{ dot1d-1998 | dot1t | legacy }
Optional.
legacy by default.
Configuring path costs of ports
When the path cost of a port changes, the system re-calculates the role of the port and initiates a state
transition.
To configure the path cost of ports:
Ste
p
Command Remarks
1. Enter system view.
system-view N/A
2. Enter interface view or port
group view.
• Enter Layer 2 Ethernet interface view or
Layer 2 aggregate interface view:
interface interface-type
interface-number
• Enter port group view:
port-group manual port-group-name
Use one of the commands.

HP 5120 EI Series Specifications

General

Brand	HP
Model	5120 EI Series
Category	Switch
Language	English