H3C Technologies H3C S5120 Series Switches - Manual (Page 188)

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The higher the maximum port rate is, the more BPDUs will be sent within each hello time, and the more
system resources will be used. By setting an appropriate maximum port rate, you can limit the rate at
which the port sends BPDUs and prevent MSTP from using excessive network resources when the
network becomes instable. We recommend that you use the default setting.
Configuring Ports as Edge Ports
If a port directly connects to a user terminal rather than another device or a shared LAN segment, this
port is regarded as an edge port. When a network topology change occurs, an edge port will not cause
a temporary loop. Because a device does not know whether a port is directly connected to a terminal,
you need to manually configure the port to be an edge port. After that, this port can transition rapidly
from the blocked state to the forwarding state without delay.
Make this configuration on the root bridge and on the leaf nodes separately.
Follow these steps to specify a port or a group of ports as edge port or ports:
To do... Use the command... Remarks
Enter system view system-view —
Enter Layer 2 Ethernet
port view, or Layer 2
aggregate port view
interface interface-type
interface-number
Enter port
view or port
group view
Enter port group view
port-group manual
port-group-name
Required
Use either command.
Configure the current ports as edge
ports
stp edged-port enable
Required
All ports are non-edge
ports by default.
z
With BPDU guard disabled, when a port set as an edge port receives a BPDU from another port, it
will become a non-edge port again. To restore the edge port, re-enable it.
z
If a port directly connects to a user terminal, configure it as an edge port and enable BPDU guard
for it. This enables the port to transition to the forwarding state fast while ensuring network security.
z
Among loop guard, root guard and edge port settings, only one function (whichever is configured
the earliest) can take effect on a port at the same time.
Configuring Path Costs of Ports
Path cost is a parameter related to the rate of a port. On an MSTP-enabled device, a port can have
different path costs in different MSTIs. Setting appropriate path costs allows VLAN traffic flows to be
forwarded along different physical links, thus achieving VLAN-based load balancing.