Configuring Interface Speed And Duplex Mode - Cisco Catalyst 2950 Software Configuration Manual

Configuring Ethernet Interfaces
Table 10-1
Feature
Broadcast, multicast, and unicast storm
control
Protected port
Port security
Port Fast
Media Type (Catalyst 2950 LRE
switches only)

Configuring Interface Speed and Duplex Mode

The 10/100 Ethernet interfaces on a non-LRE switch operate in 10 or 100 Mbps and in either full- or
half-duplex mode. The 10/100/1000 Ethernet interfaces on Catalyst 2950 LRE, Catalyst 2950T-24,
Catalyst 2950T-48-SI, and Catalyst 2955T-24 switches operate at 10 or 100 Mbps in either full- or
half-duplex mode or at 1000 Mbps only in full-duplex mode. The fiber-optic SFP-module ports on the
LRE switch operate only at 1000 Mbps in full-duplex mode.
In full-duplex mode, two stations can send and receive at the same time. When packets can flow in both
directions simultaneously, effective Ethernet bandwidth doubles to 20 Mbps for 10-Mbps interfaces,
to 200 Mbps for Fast Ethernet interfaces, and to 2 Gbps for Gigabit Ethernet interfaces. Full-duplex
communication is often an effective solution to collisions, which are major constrictions in Ethernet
networks. Normally, 10-Mbps ports operate in half-duplex mode, which means that stations can either
receive or send.
You can configure interface speed on Fast Ethernet (10/100-Mbps), Gigabit Ethernet (10/100/1000
Mbps), and LRE interfaces. You cannot configure speed on the 100BASE-FX, 1000BASE-SX,
GBIC-module, and SFP-module interfaces.
You can configure duplex mode on any Fast Ethernet interfaces that are not set to autonegotiate. You can
configure duplex mode on the 10/100/1000 ports on the Catalyst 2950 LRE, Catalyst 2950T-24,
Catalyst 2950T-48-SI, and Catalyst 2955T-24 switches but cannot configure duplex mode on these
interfaces:
•
•
•
•
•
You cannot configure speed or duplex mode on GBIC ports, but for certain types of GBICs, you can
Note
configure speed to not negotiate (nonegotiate) if connected to a device that does not support
autonegotiation.
Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide
10-10
Default Ethernet Interface Configuration (continued)
100BASE-FX ports on the Catalyst 2950C-24 switch
1000BASE-SX ports on the Catalyst 2950SX-24 switch
1000BASE-SX ports on the Catalyst 2950SX-48-SI switch
GBIC ports
Fiber-optic SFP-module ports on the Catalyst 2950 LRE switch
Chapter 10
Default Setting
Disabled. See the "Default Storm Control Configuration"
section on page 21-2.
Disabled. See the "Configuring Protected Ports" section on
page 21-4.
Disabled. See the "Default Port Security Configuration"
section on page 21-8.
Disabled.
SFP module preferred.
Configuring Interface Characteristics
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