Crossover Supported; Autonegotiation Guidelines - Alcatel-Lucent OmniSwitch 6800 Series Network Configuration Manual

Configuring Ethernet Ports
See the OmniSwitch 9000 Hardware Users Guide for more information about the OmniSwitch 9000
hardware that is available in the current release.

10/100/1000 Crossover Supported

By default, automatic crossover between MDI/MDIX (Media Dependent Interface/Media Dependent
Interface with Crossover) media is supported on OmniSwitch 9000 10/100/1000 ports. Therefore, either
straight-through or crossover cable can be used between two OmniSwitch 9000 switches as long as
autonegotiation is configured on both sides of the link. See
Settings" on page 37-16

Autonegotiation Guidelines

Please note a link will not be established on any copper Ethernet port if any one of the following is true:
•
The local port advertises 100 Mbps full duplex and the remote link partner is forced to 100 Mbps full
duplex.
•
The local port advertises 100 Mbps full duplex and the remote link partner is forced to 100 Mbps half
duplex.
•
The local port advertises 10 Mbps full duplex and the remote link partner is forced to 10 Mbps full
duplex.
•
The local port advertises 10 Mbps full duplex and the remote link partner is forced to 10 half duplex.
This is due to the fact that when the local device is set to auto negotiating 10/100 full duplex it senses the
remote device is not auto negotiating. Therefore it resolves to Parallel Detect with Highest Common
Denominator (HCD), which is "10/100 Half" according to IEEE 802.3 Clause 28.2.3.1.
However, since the local device is set to auto negotiating at 10/100 full duplex it cannot form a 10/100
Mbps half duplex link in any of the above mentioned cases. One solution is to configure the local device
to autonegotiation, 10/100 Mbps, with auto or half duplex.
OmniSwitch 6800/6850/9000 Network Configuration Guide
for more information.
"Configuring Autonegotiation and Crossover
March 2008
Ethernet Ports Overview
page 37-7