Auto-negotiation is the preferred method of configuring your system's Ethernet connections.
It should always be tried first. In auto-negotiation, your system sends
out Ethernet link pulses seeking to transfer configuration data between your
server and its link partner. Each partner shares its supported values for
line speed and duplex mode, then finds the highest common value for each.
The highest values common to both partners are selected, in this order:
10 Gbps full duplex1
- 1 Gbps full duplex2
- 1 Gbps half duplex2
- 100 Mbps full duplex
- 100 Mbps half duplex
- 10 Mbps full duplex
- 10 Mbps half duplex
Note:
- The fiber optic 10 Gigabit Ethernet adapter card can only
run either 10 Gbase-LR (long range) or 10 Gbase-SR (short range),
and full duplex. The fiber optic 10 Gigabit Ethernet adapter card does allow
auto-negotiation, but the only acceptable outcome is 10 Gbps, full duplex.
- For Gigabit Ethernet, the line speed is negotiable only when
using the UTP card, since this card has 10/100/1000BASE-T and full or half
duplex capabilities. The fiber optic Gigabit Ethernet adapter card can only
run 1000BASE-SX and full duplex. The fiber optic Gigabit Ethernet adapter
card does allow auto-negotiation, but the only acceptable outcome from the
auto-negotiation is 1000 Mbps, full duplex.
Auto-negotiation allows your server and its link partner to quickly establish a connection. However, both systems must support auto-negotiation. If the link partner is not configured to auto-negotiate, the system will auto-sense a workable line speed, but not the duplex mode. The server will use the default setting of half-duplex. If this is not the correct duplex mode, you will experience a duplex mismatch, at which point you must manually configure your server's duplex mode to match that of its link partner.