3Com Switch 4800G 24-Port Configuration Manual page 149

Enabling Flow Control
on an Ethernet Port
Configuring the
Suppression Time of
Physical-Link-State
Change on an Ethernet
Port
Enabling Loopback Test
on an Ethernet Port
To do...
Enable a specified
double Combo port
For detailed information about Combo ports and the corresponding physical ports,
refer to the installation manual.
When flow control is enabled on both sides, if traffic congestion occurs on one
side, the side will send a Pause frame notifying the peer side to temporarily
suspend the sending of packets. The peer side is expected to stop sending packets
when it receives the Pause frame. In this way, flow controls helps to avoid the
dropping of packets. Note that flow control can take effect only when it is enabled
on both sides.
Follow these steps to enable flow control on an Ethernet port:
To do...
Enter system view
Enter Ethernet port view interface interface-type interface-number
Enable flow control
An Ethernet port operates in one of the two physical link states: up or down.
During the suppression time, physical-link-state changes will not be propagated to
the system. Only after the suppression time has elapsed will the system be notified
of the physical-link-state changes by the physical layer. This functionality reduces
the extra overhead occurred due to frequent physical-link-state changes within a
short period of time.
Follow these steps to configure the suppression time of physical-link-state changes
on an Ethernet port:
To do...
Enter system view
Enter Ethernet port view
Configure the up/down
suppression time of
physical-link-state changes
You can enable loopback testing to check whether the Ethernet port functions
properly. Note that no data packets can be forwarded during the testing.
Loopback testing falls into the following two categories:
Use the command...
undo shutdown
Use the command...
system-view
flow-control
Use the command...
system-view
interface interface-type
interface-number
link-delay delay-time
Ethernet Port Configuration
Remarks
Optional
By default, out of the two ports in a
Combo port, the one with a smaller
port ID is enabled.
Remarks
-
-
Required
Turned off by default
Remarks
-
-
Required
The default suppression time
is 0 seconds, indicating that
the physical layer reports the
change of the port state to
the system right after the port
state changes.
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