Allied Telesis AT-PBC18 - Manual (Page 64)

Installing a Media Converter Module
64
In attempting to auto-negotiate with Unit 1, the media converter will
determine that the unit is capable of half-duplex only and will set the
port connected to the unit appropriately. In auto-negotiating with Unit
2, the media converter will determine that the unit can manage full-
duplex and will set the port connected to the unit to full-duplex. The
result is a mismatch, with one port on the media converter operating in
half-duplex and the other port operating in full-duplex. This is referred to
as a common duplex mode mismatch and will result in poor network
performance between the end-nodes.
Figure 26 Example of a Duplex Mode Mismatch
You can resolve a duplex mode mismatch in one of two ways:
❑ Manually configure one of the units so that its duplex mode
matches the other end-node. In the example, you could configure
Unit 2, if possible, so that the port connected to the media
converter is set to half-duplex.
❑ Disable auto-negotiation on the media converter using the auto-
negotiation switch. With auto-negotiation on the media
converter disabled, an end-node that auto-negotiates will assume
that the media converter is capable of only half-duplex operation.
In the example, with auto-negotiation disabled on the media
converter, Unit 2 will automatically set its port to half-duplex, thus
eliminating the mismatch in duplex modes between the end-
nodes.
PBC18 PWR 1 PWR 2 STATUS LINK 100M FDX RESET
PB102
100Mbps
ML
F X
T
X
R
X
M
M
LK AT
LT
MDI MDI-X
LK AT FD
ML PR
T X
PB103/1
100Mbps
ML
F X
T
X
R
X
M
M
LK AT
LT
MDI MDI-X
LK AT FD
ML PR
T X
PB102
100Mbps
ML
F X
T
X
R
X
M
M
LK AT
LT
MDI MDI-X
LK AT FD
ML PR
T X
PB13
10Mbps
ML
F L
T
X
R
X
M
M
LK RX
LT
MDI MDI-X
LK RX
ML PR
T
PB13
10Mbps
ML
F L
T
X
R
X
M
M
LK RX
LT
MDI MDI-X
LK RX
ML PR
T
PB1001/1
100Mbps
ML
L X
T
X
R
X
S
M
LK
LT
LT SA LT BB
LK
ML PR
T
X
R
X
M
M S X
CLASS 1 LASER PRODUCT
DO NOT STARE INTO BEAM
PB102
100Mbps
ML
F X
T
X
R
X
M
M
LK AT
LT
MDI MDI-X
LK AT FD
ML PR
T X
PB103/1
100Mbps
ML
F X
T
X
R
X
M
M
LK AT
LT
MDI MDI-X
LK AT FD
ML PR
T X
PB102
100Mbps
ML
F X
T
X
R
X
M
M
LK AT
LT
MDI MDI-X
LK AT FD
ML PR
T X
PB13
10Mbps
ML
F L
T
X
R
X
M
M
LK RX
LT
MDI MDI-X
LK RX
ML PR
T
PB13
10Mbps
ML
F L
T
X
R
X
M
M
LK RX
LT
MDI MDI-X
LK RX
ML PR
T
PB102
100Mbps
ML
F X
T
X
R
X
M
M
LK AT
LT
MDI MDI-X
LK AT FD
ML PR
T X
PB103/1
100Mbps
ML
F X
T
X
R
X
M
M
LK AT
LT
MDI MDI-X
LK AT FD
ML PR
T X
PB13
10Mbps
ML
F L
T
X
R
X
M
M
LK RX
LT
MDI MDI-X
LK RX
ML PR
T
PB13
10Mbps
ML
F L
T
X
R
X
M
M
LK RX
LT
MDI MDI-X
LK RX
ML PR
T
PB13
10Mbps
ML
F L
T
X
R
X
M
M
LK RX
LT
MDI MDI-X
LK RX
ML PR
T
PB1001/1
100Mbps
ML
L X
T
X
R
X
S
M
LK
LT
LT SA LT BB
LK
ML PR
T
X
R
X
M
M S X
CLASS 1 LASER PRODUCT
DO NOT STARE INTO BEAM
PB1001/1
100Mbps
ML
L X
T
X
R
X
S
M
LK
LT
LT SA LT BB
LK
ML PR
T
X
R
X
M
M S X
CLASS 1 LASER PRODUCT
DO NOT STARE INTO BEAM
Unit 1: Ethernet Hub
Unit 2: Ethernet Switch
(Half-duplex only)
(Auto-negotiate)
PowerBlade PBC18