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10—Configures the port to 10 Mbps operation.
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100—Configures the port to 100 Mbps operation.
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1000—Configures the port to 1000 Mbps operation.
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10000—Configures the port to 10 Gbps operation.
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40000—Configures the port to 40 Gbps operation.
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auto—The port automatically negotiates the highest common speed with
the port at the other end of the link. If you use the 10, 100, 1000, 2500,
5000, or 10000 keywords with the auto keyword, the port only advertises
the specified speeds.
Default Configuration
Auto-negotiation is enabled by default on copper ports and SFP ports.
Command Mode
Interface Configuration (Ethernet) mode
User Guidelines
Not all interfaces are capable of supporting all speeds. Refer to the Hardware
Overview section of the Users Configuration Guide for a description of the
capabilities of a particular interface.
Use the auto parameter to enable auto-negotiation on an interface. Auto-
negotiation on copper interfaces selects a clock master, performs link training
to tune the pre-emphasis settings to the individual switch and cable,
negotiates the internal media, and may enable a decision feedback equalizer
(DFE) to correct burst errors if the PHY has the capability. To disable auto-
negotiation on a port, it is necessary to enter the speed command without
using the auto parameter. Disabling auto-negotiation on 1G copper ports
may lead to random frame loss as the clock master and media have not been
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. Auto-negotiation is also required on 1000Base-
X ports (including SFP fiber ports.)
When the auto parameter is configured with a set of speeds, only those
speeds are advertised during auto-negotiation. Alternatively, if no speed
arguments are configured, then all the speeds which the port is capable of
Layer 2 Switching Commands
417
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