ZyXEL Communications MES3500 Series User Manual page 88

Table 14 Basic Setting > Port Setup (continued)
LABEL DESCRIPTION
Speed/Duplex Select the speed and the duplex mode of the Ethernet connection on this port. Choices are
Auto, 10M/Half Duplex, 10M/Full Duplex, 100M/Half Duplex, 100M/Full Duplex and
1000M/Full Duplex (Gigabit connections only).
Selecting Auto (auto-negotiation) allows one port to negotiate with a peer port automatically
to obtain the connection speed and duplex mode that both ends support. When auto-
negotiation is turned on, a port on the Switch negotiates with the peer automatically to
determine the connection speed and duplex mode. If the peer port does not support auto-
negotiation or turns off this feature, the Switch determines the connection speed by
detecting the signal on the cable and using half duplex mode. When the Switch's auto-
negotiation is turned off, a port uses the pre-configured speed and duplex mode when
making a connection, thus requiring you to make sure that the settings of the peer port are
the same in order to connect.
Flow Control A concentration of traffic on a port decreases port bandwidth and overflows buffer memory
causing packet discards and frame losses. Flow Control is used to regulate transmission of
signals to match the bandwidth of the receiving port.
The Switch uses IEEE802.3x flow control in full duplex mode and backpressure flow control in
half duplex mode.
IEEE802.3x flow control is used in full duplex mode to send a pause signal to the sending
port, causing it to temporarily stop sending signals when the receiving port memory buffers
fill.
Back Pressure flow control is typically used in half duplex mode to send a "collision" signal to
the sending port (mimicking a state of packet collision) causing the sending port to
temporarily stop sending signals and resend later. Select Flow Control to enable it.
802.1p This priority value is added to incoming frames without a (802.1p) priority queue tag. See
Priority Priority Queue Assignment in
Apply Click Apply to save your changes to the Switch's run-time memory. The Switch loses these
changes if it is turned off or loses power, so use the Save link on the top navigation panel to
save your changes to the non-volatile memory when you are done configuring.
Cancel Click Cancel to begin configuring this screen afresh.
Chapter 8 Basic Setting
Table 12 on page 83
MES3500/MGS3520 Series User's Guide
88
for more information.