To configure the speed for a given Ethernet interface when not using
auto-negotiation, use the speed Interface Configuration
mode command.
Syntax
speed {10 | 100 | 1000 | 10000 | auto}
Parameters
10—Enables 10-Mbps operation.
100—Enables 100-Mbps operation.
1000—Enables 1000-Mbps operation.
10000—Enables 10000-Mbps operation.
Auto—Enables auto speed configuration. The port automatically detects the speed at which it should run at based on the port at
the other end of the link. If you use the 10, 100, or 1000 keywords with the auto keyword, the port only auto-negotiates at
the specified speed.
Default Configuration
The port operates at its maximum speed capability.
Command Mode
Interface Configuration (Ethernet, port channel) mode
User Guidelines
For 10/100-Mbps ports, if both speed and duplex are set to specific values, the link operates at the negotiated speed and
duplex value.
For 10/100/1000-Mbps ports, if both the speed and duplex are set to specific values, autonegotiation is disabled.
You can configure the Fast Ethernet port speed as either 10 or 100 Mbps. You cannot configure the speed on the SFP module
ports, but you can configure the speed to not negotiate (nonegotiate) if it is connected to a device that does not support
autonegotiation. However, when a 1000BASE-T SFP module is inserted into the SFP module port, you can configure the speed as
10, 100, 1000 Mbps, or auto.
If the speed is set to auto, the switch negotiates with the device at the other end of the link for the speed setting and
then forces the speed setting to the negotiated value. The duplex setting remains as configured on each end of the link, which
could result in a duplex setting mismatch.
If both ends of the line support autonegotiation, we highly recommend that you use the default autonegotiation settings. If
one interface supports autonegotiation and the other end does not, you must manually configure the duplex and speed settings
on the other side.
Example
The following example configures the speed of fa5 to 100 Mbps:
switchxxxxxx(config)# interface gi5
switchxxxxxx(config-if)# speed 100