3Com Switch 7757, Configuration Manual

Page: 176 / 940

176 C
HAPTER
22: P
ORT
B
ASIC
C
ONFIGURATION
Enabling Flow Control
on a Port
Flow control is enabled on both the local and peer switches. If congestion occurs
on the local switch:
■
The local switch sends a message to notify the peer switch of stopping sending
packets to itself temporarily.
■
The peer switch will stop sending packets to the local switch or reduce the
sending rate temporarily when it receives the message; and vice versa. By this
way, packet loss is avoided and the network service operates normally.
Configuring a Delay for
Reporting a Port
Physically Down Event
The physical state of an Ethernet port is either up or down. In normal cases,
immediately after the physical state changes, the port reports the event to the
system. This can be resource consuming when state changing is frequent in a
short period of time.
You can address the problem by introducing a delay for reporting the physically
down event of a port. With this delay, a port reports a physically down event after
the delay expires rather than doing that immediately upon occurrence of the
down event. You can thus affect how soon the system can obtain the physical
state of its ports.
n
■
The delays set with the above commands are weight values rather than exact
time values. The greater the delay weight, the longer the delay.
■
You can set the delay of reporting down state either in system view or Ethernet
port view. If you perform this configuration in both system view and Ethernet
port view, the configuration performed in Ethernet port view is given priority.
Table 110 Enable flow control on a port
Operation Command Description
Enter system view system-view -
Enable flow control globally flow-control enable Required
By default, flow control is
disabled globally.
Enter Ethernet port view interface interface-type
interface-number
-
Enable flow control on the
Ethernet port flow-control Required
By default, flow control is
disabled on the port.
Table 111 Configure a delay for reporting a port physically down event
Operation Command Description
Enter system view system-view -
Set the delay of reporting
down state for the ports of all
I/O Modules or the specified
I/O Module port monitor last [ slot
slot-number ] value
Optional
By default, the report delay is
1.
Enter Ethernet port view interface interface-type
interface-number
-
Set the down event reporting
delay on the current port port monitor last [ value ] Optional
By default, the delay setting is
the same as the global setting
in system view.