Allied Telesis AT-PBC18 - Manual (Page 63)

PowerBlade PBC18 Installation Guide
63
Auto-negotiation
Switch
The AT-PB100 Series Media Converters feature an auto-negotiation
switch on the board that disables the auto-negotiation feature (IEEE
802.3u) of the media converter. In most configurations you should leave
the auto-negotiation feature enabled so the unit can automatically
determine the appropriate duplex mode, based on the capabilities of
the end-nodes. For example, the auto-negotiation feature on the media
converter should be left enabled in situations where both end-nodes are
also capable of auto-negotiation or where both end-nodes have been
pre-set to the same mode, such as half-duplex. Figure 25 shows the
location of the auto-negotiation switch for the AT-PB100 Series Media
Converters.
Figure 25 Auto-negotiation Switch
There is one situation, however, where it may be necessary to disable the
auto-negotiation feature, and that is to prevent a mismatch from
occurring between the duplex modes of the end-nodes. For example,
Figure 26 shows two units that have been connected with a AT-PB100
Series Media Converter. Unit 1 is an Ethernet hub that is capable of
operating in half-duplex mode only. Unit 2 is a switch that can operate in
either half- or full-duplex mode, and will auto-negotiation the duplex
mode.
PB101
100Mbps
ML
F
L
T
T
X
R
X
M
M
LK RX
LT
MDI
MDI-X
LK RX
ML PR
B A
Auto-negotiation Switch
A = ON / B = OFF