Nortel Networks 450 - Manual (Page 234)

Using the BayStack 450 10/100/1000 Series Switch
4-8 302401-D Rev 00
Autonegotiation Modes
Port connection problems can occur when a port (or station) is connected to
another port (or station) that is not operating in a compatible mode (for example,
connecting a full-duplex port on one station to a half-duplex port on another
station).
The BayStack 450 switch negotiates port speeds according to the IEEE 802.3u
autonegotiating standard. The switch adjusts (autonegotiates) its port speed and
duplex mode to match the best service provided by the connected station, up to
100 Mb/s in full-duplex mode.
• If the connected station uses a form of autonegotiation that is not compatible
with the IEEE 802.3u autonegotiating standard, the BayStack 450 switch
cannot negotiate a compatible mode for correct operation.
• If the autonegotiation feature is not present or not enabled at the connected
station, the BayStack 450 switch may not be able to determine the correct
duplex mode.
In both situations, the BayStack 450 switch “autosenses” the speed of the
connected station and, by default, reverts to half-duplex mode. If the connected
station is operating in full-duplex mode, it cannot communicate with the switch.
To correct this mode mismatch problem:
1. Use the Port Configuration screen to disable autonegotiation for the
suspect port (see “Port Configuration” on page 3-32).
2. Manually set the Speed/Duplex field to match the speed/duplex mode of
the connected station (see Table 3-12 on page 3-33).
You may have to try several settings before you find the correct speed/duplex
mode of the connected station.
If the problem persists:
1. Disable the autonegotiation feature at the connected station.
2. Manually set the speed/duplex mode of the connected station to the same
speed/duplex mode you have manually set for the BayStack 450 switch
port.
kombk.book Page 8 Tuesday, June 29, 1999 3:25 PM