Cisco Catalyst 3750 Series Switches SFP Port Connections

Updated on Oct 15, 2021 by

The Cisco Catalyst 3750 series switches have impressed many network engineers in the past days when 10G back-bone at full steam. With a range of Fast Ethernet and Gigabit Ethernet configurations, they can serve as both powerful access layer switches for medium enterprise wiring closets and as backbone switches for mid-sized networks. This post will offer detailed information about Cisco Catalyst 3750 series switches and their port connections.

Cisco catalyst 3750 series switch and FS.com optics

Figure 1: FS Test Assured Program

Cisco Catalyst 3750 Series Switches Introduction

Cisco Catalyst 3750 is a series of switches providing flexible configuration and supports converged network pattern, which makes the management and organization of the network become easier and more flexible. One of the biggest characteristics of Cisco 3750 Network Switch is that they are armed with StackWise ports on their rear panel that can support Cisco StackWise technology (as shown below). With StackWise technology, up to nine physical Catalyst 3750 switches can be interconnected into one logical switch with a high performance of 32G or 128G (by Catalyst 3750-E switch series). The following picture shows the rear panel of a Cisco Catalyst 3750 switch.

Cisco Catalyst 3750G-48TS rear panel

Cisco Catalyst 3750 Series Switches Models Comparison

Like other series switches, the Cisco 3750 series 24/48 port switch is also composed of different models. The following table shows the list of Cisco Catalyst 3750 series models:

Models Ports
WS-C3750-48TS-E 48 10/100 ports + 4 SFP-based Gigabit Ethernet ports
WS-C3750-48TS-S 48 10/100 ports + 4 SFPs
WS-C3750-24TS-E 24 10/100 ports + 2 SFP-based Gigabit Ethernet ports
WS-C3750-24TS-S 24 10/100 ports + 2 SFP-based Gigabit Ethernet ports
WS-C3750G-24TS-E 24 10/100/1000 ports
WS-C3750G-24TS-S 24 10/100/1000 ports
WS-C3750G-24T-E 24 10/100/1000 ports
WS-C3750G-24T-S 24 10/100/1000 ports

Connecting Cisco Catalyst 3750 Series in Network

As mentioned that Cisco Catalyst 3750 series switches have different ports including RJ45 ports and SFP ports which can support data rate ranging from 10M to 1G. And cables and connectors used to connect the switches to the network are also different depending on the form and data rate of the ports.

Cisco Catalyst 3750G-48TS front panel

10/100/1000 Ports Connections

The 10/100/1000 Ethernet ports on Cisco Catalyst 3750 switches uses standard RJ45 connectors, which are bases on copper cables (shown in the following picture). Here are some tips for selecting the related copper cables. When connecting Catalyst 3750 to workstations, servers, routers, connect a straight-through cable to an RJ45 connector on the front panel; When connecting to switches or repeaters, use a crossover cable; When connecting to 1000Base-T-compatible devices, be sure to use a twisted four-pair, Cat5 cable.

Cisco Catalyst 3750 RJ45 connection

SFP Module Ports Connections

Some of the Cisco Catalyst 3750 series switches have several SFP module ports on the front panel. By using Gigabit Ethernet SFP modules, Gigabit copper or fiber optic uplinks can be built. Cisco Catalyst 3750 switches SFP ports can support a variety of SFP modules. These ports can be connected with fiber optic SFP modules like 1000Base-LX and 1000Base-SX and copper SFP modules like 1000Base-T. The following picture illustrates the connections with fiber optic SFP module port and Copper SFP module port from left to right separately.

Cisco catalyst 3750 SFP port connection

Cisco Catalyst 3750 Series Switches Cabling Solution

More related cables and modules that Cisco Catalyst 3750 switches supporting are listed in the following chart for your reference.

Port Type Data Rate Connectors/Modules Cables
RJ45 Ports 10BASE-T Ports RJ-45 connectors, two-pair Cat 3, 4, or 5 unshielded twisted-pair (UTP)
10BASE-T PoE Ports RJ-45 connectors , two-pair Cat 3, 4, or 5 UTP cabling power pins 1, 2 (negative) and 3, 6 (positive)
100BASE-TX Ports RJ-45 connectors, two-pair Cat 5 UTP
100BASE-TX PoE Ports RJ-45 connectors, two-pair Cat 5 UTP, power on pins 1, 2 (negative) and 3, 6 (positive)
SFP Ports 100M GLC-GE-100FX LC duplex, MMF
GLC-FE-100LX LC duplex, MMF
GLC-FE-100BX-D LC simplex, SMF
1G GLC-SX-MM LC duplex, MMF
GLC-BX-U LC simplex, SMF
GLC-T RJ-45, Cat 5


Being an innovative product line that improves LAN operating efficiency, the Cisco Catalyst 3750 series switches represent the next generation in desktop switches. They allow customers to build a unified, highly resilient switching system. Thus, many companies use Cisco Catalyst 3750 series switches as layer 3 switches. When connecting Cisco Catalyst 3750 series switches to your network, remember to use the proper cables and transceivers for better performance.

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