Cisco Systems WSC3750X24TS specifications Device, Crossover Cable, 2-40, Straight-Through Cable

Chapter 2 Switch Installation

Connecting to the 10/100 and 10/100/1000 Ports

Table 2-1	Recommended Ethernet Cables
Device		Crossover Cable1	Straight-Through Cable1
Switch to switch		Yes	No
Switch to hub		Yes	No
Switch to computer		No	Yes
or server
Switch to router		No	Yes
Switch to IP phone		No	Yes

1.100BASE-TX and 1000BASE-T traffic requires twisted four-pair, Category 5 or higher cable. 10BASE-T traffic can use Category 3 or Category 4 cable.

You can use the mdix auto interface configuration command in the CLI to enable the automatic medium-dependent interface crossover (auto-MDIX) feature. When the auto-MDIX feature is enabled, the switch detects the required cable type for copper Ethernet connections and configures the interfaces accordingly. Therefore, you can use either a crossover or a straight-through cable for connections to a copper 10/100, 10/100/1000, or 1000BASE-T SFP module port on the switch, regardless of the type of device on the other end of the connection.

The auto-MDIX feature is enabled by default on switches running Cisco IOS Release 12.2(18)SE or later. For releases between Cisco IOS Release 12.1(14)EA1 and 12.2(18)SE, the auto-MDIX feature is disabled by default. For configuration information for this feature, see the switch software configuration guide or the switch command reference.

Follow these steps to connect to 10BASE-T, 100BASE-TX or 1000BASE-T devices:

Caution PoE faults are caused when noncompliant cabling or powered devices are connected to a PoE port. Only standard-compliant cabling can be used to connect Cisco pre-standard IP Phones and wireless access points or IEEE 802.3af-compliant devices to PoE ports. A cable or device that causes a PoE fault must be removed from the network.

Step 1 When you connect the switch to workstations, servers, routers, and Cisco IP Phones, connect a straight-through cable to an RJ-45 connector on the front panel. (See Figure 2-55.) When you connect the switch to other switches or to repeaters, use a crossover cable. (See the “Cable and Adapter Specifications” section on page B-5for cable-pinout descriptions.)

When you connect a switch to 1000BASE-T-compatible devices, be sure to use a twisted four-pair, Category 5 or later cable.

You can connect the Catalyst 3750 switch to a Cisco IP Phone through a straight-through, twisted four-pair Category 5 or later cable. The rear panel of the Cisco IP Phone might have more than one RJ-45 connector. Use the LAN-to-phone connector to connect the Cisco IP phone to the switch. See the Cisco IP Phone documentation for more information about connecting devices to it.

Note Many legacy powered devices, including older Cisco IP phones and access points that do not fully support IEEE 802.3af, might not support PoE when connected to the switches by a crossover cable.

Catalyst 3750 Switch Hardware Installation Guide

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