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10-11
Catalyst 2960 Switch Software Configuration Guide
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Chapter 10 Configuring Interface Characteristics
Configuring Ethernet Interfaces
Speed and Duplex Configuration Guidelines
When configuring an interface speed and duplex mode, note these guidelines:
• Fast Ethernet (10/100-Mbps) ports support all speed and duplex options.
• Gigabit Ethernet (10/100/1000-Mbps) ports support all speed options and all duplex options (auto,
half, and full). However, Gigabit Ethernet ports operating at 1000 Mbps do not support half-duplex
mode.
• For SFP module ports, the speed and duplex CLI options change depending on the SFP module type:
–
The 1000BASE-x (where -x is -BX, -CWDM, -LX, -SX, and -ZX) SFP module ports support
the nonegotiate keyword in the speed interface configuration command. Duplex options are not
supported.
–
The 1000BASE-T SFP module ports support the same speed and duplex options as the
10/100/1000-Mbps ports.
–
The 100BASE-x (where -x is -BX, -FX, -FX-FE, and - LX) SFP module ports support only
100 Mbps. These modules support full- and half- duplex options but do not support
autonegotiation.
For information about which SFP modules are supported on your switch, see the product release
notes.
• If both ends of the line support autonegotiation, we highly recommend the default setting of auto
negotiation.
• If one interface supports autonegotiation and the other end does not, configure duplex and speed on
both interfaces; do not use the auto setting on the supported side.
• When STP is enabled and a port is reconfigured, the switch can take up to 30 seconds to check for
loops. The port LED is amber while STP reconfigures.
Caution Changing the interface speed and duplex mode configuration might shut down and re-enable the
interface during the reconfiguration.
Setting the Type of a Dual-Purpose Uplink Port
Some Catalyst 2960 switches support dual-purpose uplink ports. For more information, see the
“Dual-Purpose Uplink Ports” section on page 10-4.
Beginning in privileged EXEC mode, follow these steps to select which dual-purpose uplink to activate so
that you can set the speed and duplex. This procedure is optional.
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
interface interface-id Specify the dual-purpose uplink port to be configured, and enter
interface configuration mode.