FCM9002 USER MANUAL
76-02-095 Rev.B
Page 77 of 145
4.4.1.5 Auto Negotiation
Auto Negotiation allows the port to automatically determine the best operating
parameters for the port. If both link partners support auto negotiation then they
will select the best mode that is supported by both devices.
If one link partner does not support auto negotiation, an auto negotiating link
partner will be able to determine the link speed, however it will be unable to
determine the duplex mode so will default to the half duplex state.
An auto port connected to a non auto port is a very common fault on networks
leading to errors on the line when significant traffic is flowing, but appearing to
operate normally when diagnostics like ping are used to test the link.
4.4.1.6 Negotiated
When auto negotiation is enabled, the negotiated display item shows the
operating mode that has be negotiated between the link partners.
10M/HD
10 Base T / Half Duplex
10M/FD
10 Base T / Full Duplex
100M/HD
100 Base T / Half Duplex
100M/FD
100 Base T / Full Duplex
1000M/HD
1000 Base T / Half Duplex
1000M/FD
1000 Base T / Full Duplex
4.4.1.7 MDI / MDIX
There are two possible pin outs for the RJ45 physical ports, one is defined as
MDI and is typically found on data sources such as PC’s or Laptops. The other
is defined as MDIX, or MDI Crossover is typically found on switches. In order to
use a straight through patch cable, an MDI port must connect to an MDI-X port
otherwise crossover cables are required.
The FCM9002 LAN ports support auto switching technology whereby the port will
automatically detect whether it should be MDI or MDIX and will configure itself
accordingly. With auto switching ports, only straight patch cables are required.
