CLI Guide

Table Of Contents
Layer 2 Switching Commands 437
arbitrated by the auto-negotiation process. Auto-negotiation is required on
2.5G/5G/10G/40G copper ports and is always recommended for copper ports
regardless of the speed setting. SFP+ ports utilizing a copper DAC cable are
considered copper ports. Auto-negotiation is also required on 1000Base-X
ports (including SFP fiber ports.)
If using combinations of the 10, 100, 1000, 2500, 5000, 10000, 25000, or
40000 keywords with the auto keyword. the port only advertises the specified
speeds. Alternatively, if no speed arguments are configured, then all the
speeds which the port is capable of supporting are advertised. Not all ports
speeds or combination of speeds are available on all platforms or ports.
Entering an unsupported speed will produce the following error message An
invalid interface has been used for this function.
Fiber ports (other than 1000Base-X) do not support auto-negotiation and
therefore require the operator to enter the speed command with the desired
operating rate. The link partner must be similarly configured. SFP+/QSFP
fiber ports using fiber media do not support auto-negotiation, although it
must be enabled when using Direct Attach Copper cables if the link partner
also supports auto-negotiation. 1G SFP fiber ports should have auto-
negotiation enabled. SFP transceivers in an SFP+ port should have auto-
negotiation enabled. The default behavior is to enable auto-negotiation when
an SFP transceiver is inserted into an SFP+ port, unless a fixed speed is
configured.
Likewise, SFP+ ports connected via copper Direct Attach Cables must have
auto-negotiation enabled if the link partner is also capable of performing
auto-negotiation. If the link partner cannot perform auto-negotiation, then a
fixed speed must be utilized. In all cases, the link partners need compatible
settings, e.g., both sides must be set to use auto-negotiation or a fixed speed.
In the case of a fixed speed link, both sides must be set to the same speed.
Failure to set both sides of a link to the same speed/duplex values (auto-
negotiation disabled) or compatible speed/duplex values (auto-negotiation
enabled) may give a false link-up indication when configured or when the link
is brought up (no shut). Setting one end of a link to auto-negotiate and the
link partner to a fixed speed is not supported. Disabling auto-negotiation on
interfaces that require it, for example, 1000BASE-X or 1G/10G copper
interfaces, is not supported.