Vlans - 3Com 9100 User Manual

Using the Command-Line Interface 153
A mismatch of duplex mode between the Switch 9100 and the network
device will cause poor network performance. Viewing using the
show
command on the Switch 9100 may display a constant increment
port rx
of CRC errors. This is characteristic of a duplex mismatch between
devices. This is NOT a problem with the switch.
Always verify that the switch and the network device match in
configuration for speed and duplex.
No link light on Gigabit fiber port:
Check to ensure that the transmit fiber goes to the receive fiber side of
the other device, and vice-versa. All gigabit fiber cables are of the
cross-over type.
The Switch 9100 has auto-negotiation set to on by default for gigabit
ports. These ports need to be set to auto off (using the command
config
) if you are connecting it to devices that do not
port <port #> auto off
support auto-negotiation.
Ensure that you are using multi-mode fiber (MMF) when using a
1000BASE-SX port. 1000BASE-SX does not work with SMF.

VLANs

You cannot add a port to a VLAN:
If you attempt to add a port to a VLAN and get an error message similar
to
localhost:7 # config vlan marketing add port 1,2
ERROR: Protocol conflict on port 5
you already have a VLAN using untagged traffic on a port. Only one
VLAN using untagged traffic can be configured on a single physical port.
VLAN configuration can be verified by using the following command:
show vlan <name>
The solution for this error is to remove ports 1 and 2 from the VLAN
currently using untagged traffic on those ports. If this were the "default"
VLAN, the command would be
localhost:23 # config vlan default del port 1,2