Straight Through Cable: Color Code, Wiring, Uses, and Crossover Difference

A straight-through cable is an Ethernet cable with the same wiring order on both RJ45 connectors. It can be terminated as T568A-to-T568A or T568B-to-T568B. It is normally used to connect different device types, such as a computer to a switch, a router to a switch, a firewall to a switch, or a wireless access point to an access switch.

The operating rule is straightforward: if both ends use the same wiring standard, the cable is straight-through. If one end uses T568A and the other end uses T568B, the cable is crossover. That distinction matters when checking old patch cords, troubleshooting link problems, or validating cabling before a switch, router, firewall, camera, phone, or access point deployment.

What Is a Straight Through Cable?

A straight-through cable uses identical pin order on both ends of the Ethernet cable. Pin 1 connects to pin 1, pin 2 connects to pin 2, and the same pattern continues through pin 8. Most pre-made Ethernet patch cables used in offices, network closets, and equipment racks are straight-through cables.

Straight-through cables are the default choice for ordinary Ethernet patching. Use them for endpoint-to-switch connections, router-to-switch handoffs, firewall-to-switch links, IP phone connections, camera connections, and most access point cabling. Modern access switches usually support Auto-MDI/MDIX, which reduces the need for crossover cables in switch-to-switch links.

Straight Through Cable Color Code

A straight-through cable can use either T568A or T568B, but both ends must use the same standard. T568B-to-T568B is the most common form in commercial patch cords and enterprise LAN environments. T568A-to-T568A is also a valid straight-through cable when a site standard or project document requires it.

Cable wiring	End A	End B	Result
T568A straight-through	T568A	T568A	Straight-through cable
T568B straight-through	T568B	T568B	Straight-through cable
Mixed wiring	T568A	T568B	Crossover cable

T568A and T568B are covered here only as they apply to straight-through cables. For full RJ45 pinout diagrams, wiring-standard background, and a deeper comparison of the two standards, use the T568A vs T568B wiring guide.

T568B Straight Through Cable Color Order

T568B is the most common wiring order for commercial Ethernet patch cables. A T568B straight-through cable uses the following color order on both RJ45 connectors.

Pin	T568B color
1	White/Orange
2	Orange
3	White/Green
4	Blue
5	White/Blue
6	Green
7	White/Brown
8	Brown

If both connectors follow this same order, the cable is T568B straight-through. If one connector follows T568B and the other follows T568A, the cable is not straight-through; it is a crossover cable.

In most business networks, T568B is a practical default because many pre-terminated patch cords and existing commercial cabling systems use it. Consistency still matters more than preference. Match the site standard already used in the patch panel, wall outlet, or structured cabling documentation.

T568A Straight Through Cable Color Order

T568A is also a valid straight-through wiring standard. A T568A straight-through cable uses the following color order on both RJ45 connectors.

Pin	T568A color
1	White/Green
2	Green
3	White/Orange
4	Blue
5	White/Blue
6	Orange
7	White/Brown
8	Brown

If both connectors follow this same order, the cable is T568A straight-through. T568A is common in some residential, government, and legacy environments. It should be used when the building standard, contract requirement, or existing cabling plant already uses T568A.

Do not choose T568A or T568B because one is expected to be faster. The selected standard does not determine Ethernet speed or PoE power delivery. Cable category, termination quality, cable length, switch port capability, and endpoint support determine whether a link can reliably run at 1G, 2.5G, 5G, or 10G.

Straight Through vs Crossover Cable

The difference between straight-through and crossover cable is the wiring pattern at the two RJ45 ends. A straight-through cable uses the same pinout on both ends. A crossover cable uses T568A on one end and T568B on the other end, which swaps the transmit and receive pairs used by older Ethernet devices.

For the full crossover wiring, pinout, Auto-MDIX behavior, and when you still need one, see our crossover cable guide.

Item	Straight-through cable	Crossover cable
RJ45 wiring pattern	Same standard on both ends	T568A on one end, T568B on the other
Common example	T568B-to-T568B	T568A-to-T568B
Typical use	Different device types	Similar device types in older networks
Common connection	PC to switch, router to switch, AP to switch	PC to PC, switch to switch in legacy designs
Modern relevance	Standard patch cable	Rare unless a project or old device requires it
Buying risk	Wrong category or low-quality cable	Usually unnecessary in modern access networks

Older Ethernet designs often required crossover cables when connecting similar devices, such as switch to switch or PC to PC. Most modern Ethernet ports can automatically detect and correct the transmit/receive pairing, so a straight-through cable is usually accepted even where a crossover cable was once required.

For real deployments, do not decide only from a generic rule. Check the device documentation, cabling standard, and existing patching practice if the link involves older switches, industrial devices, lab equipment, unmanaged equipment, or a known fixed MDI/MDIX port.

When to Use a Straight Through Cable

Use a straight-through cable for most ordinary Ethernet connections in an office, branch, campus, warehouse, or equipment room. The most common pattern is an endpoint or network edge device connecting to an access switch.

Computer, Printer, Camera, or Access Point to Switch

Use straight-through cable when connecting a PC, printer, IP camera, IP phone, wireless access point, badge reader, thin client, or other endpoint to an access switch. This is the normal patching model for Cisco Catalyst access switches in enterprise LANs.

For PoE endpoints, the cable type is only one part of the decision. Confirm cable category, cable length, connector quality, and the switch PoE budget. A poorly terminated or damaged patch cord can cause link flaps, reduced negotiated speed, camera power instability, or access point power warnings even when the wiring pattern is technically straight-through. For projects built around phones, cameras, and APs, check the required PoE switch options and the exact endpoint load before finalizing the patch-cord list.

Router, Firewall, or Modem Handoff to Switch

Use straight-through cable when connecting a router LAN interface, firewall interface, or modem/ONT handoff into a switch, unless the provider or hardware document specifies a different media type. Many WAN edge deployments use a copper handoff from the provider device into a Cisco router or Cisco Firepower firewall, then from that device into a switch.

If the deployment question is where the ISP modem or ONT should connect, the port choice matters more than the cable pattern. The provider handoff normally connects to a WAN or outside interface, while internal devices connect to LAN or switch ports.

Server to Access or Top-of-Rack Switch

Use straight-through copper patch cables for standard RJ45 server connections to an access switch or top-of-rack switch. This applies to ordinary copper server NICs and management ports, including out-of-band management connections where RJ45 Ethernet is used.

For higher-speed server links, do not assume copper patch cable is the correct medium. Some designs use fiber, DAC, AOC, or Cisco optical modules instead of RJ45 patch cords. For copper-versus-fiber planning, compare distance, speed, port type, and transceiver requirements before selecting the cable and transceiver mix.

Switch to Switch in Modern Networks

Modern switch-to-switch copper links often work with a straight-through cable because Auto-MDI/MDIX can adjust the port internally. This is why crossover cables are rarely stocked for ordinary office and campus networks today.

There are still exceptions. Older switches, unmanaged industrial devices, lab equipment, and some fixed-function appliances may behave differently. If a switch-to-switch copper link does not come up, verify speed and duplex negotiation, port state, cable tester results, and whether a crossover cable is required by the device documentation.

How to Identify a Straight Through Cable

The fastest way to identify a straight-through cable is to compare both RJ45 connectors. Hold both plugs in the same orientation and check whether the wire colors appear in the same left-to-right order. If the order is identical on both ends, the cable is straight-through.

Visual inspection is useful for transparent connectors, but it is not enough for production cabling. Poor crimps, split pairs, damaged conductors, and weak terminations may not be visible. For installed cabling, use a cable tester or certification report instead of relying on jacket labels or visual checks alone.

Check	What to look for	Why it matters
Connector color order	Same order on both ends	Confirms straight-through wiring pattern
Cable tester result	Pin 1 to 1, 2 to 2, through 8 to 8	Confirms pin-to-pin continuity
Patch panel record	Matches site wiring standard	Prevents mixing standards by accident
Cable category marking	Cat5e, Cat6, Cat6A, or project-specified category	Confirms speed and installation suitability
Physical condition	No broken latch, crushed jacket, loose boot, or exposed conductor	Reduces intermittent link issues

Do not use cable jacket color to decide whether a cable is straight-through or crossover. The outer jacket color is only a site labeling choice. Blue, gray, yellow, red, or black patch cords can all be wired as straight-through or crossover.

Straight Through Cable Wiring Diagram

In a straight-through cable, each pin connects to the same pin number on the far end. Pin 1 connects to pin 1, pin 2 connects to pin 2, pin 3 connects to pin 3, and the pattern continues through pin 8. This keeps the two RJ45 ends electrically aligned.

RJ45 pin on End A	RJ45 pin on End B
1	1
2	2
3	3
4	4
5	5
6	6
7	7
8	8

The wiring order still matters because Ethernet uses twisted pairs, not just eight individual wires. Keeping the correct pair relationship is important for signal quality, especially on Gigabit Ethernet and faster copper links. A cable can show continuity but still perform poorly if the pairs were untwisted too far or terminated incorrectly.

For new site work, installed cabling should be tested against the required category and link length. A cable that works at 100 Mbps during a quick check may still fail the real requirement for 1G, 2.5G, 5G, 10G, or high-power PoE endpoints.

Do Modern Cisco Switches Still Need Crossover Cables?

Most modern Cisco switch deployments do not require crossover cables for ordinary Ethernet links. Auto-MDI/MDIX support allows the port to detect and adjust for the cable wiring in many common scenarios, which makes straight-through patch cables the normal choice for endpoint, access switch, router, and firewall connections.

That does not mean crossover cables are impossible to use or never required. Some older devices, lab devices, industrial endpoints, and unmanaged equipment may still require a specific cable type. If a project specification calls for crossover cable, follow the specification or confirm with the network engineer before substituting a straight-through patch cord.

From a stocking and procurement standpoint, straight-through cables should be the default patch-cord inventory for modern enterprise access networks. Crossover cables should be treated as a special-purpose item, not a general replacement for standard Ethernet patch cords.

Ethernet Cable Category for Straight Through Cable

Straight-through describes the wiring pattern, not the cable performance class. A Cat5e, Cat6, or Cat6A cable can all be wired as straight-through. The right choice depends on endpoint speed, PoE load, cable run, installation environment, and the switch ports being deployed. For quote preparation, the cable decision should sit beside the switch, AP, router, firewall, optics, and accessory lines in the same BOM.

Use case	Practical cable choice	Planning note
1G desktop, printer, or IP phone	Cat5e or Cat6	Cat6 is often preferred for new office patching
Wi-Fi 6 or Wi-Fi 6E access point	Cat6 or Cat6A	Confirm PoE demand and negotiated port speed
2.5G or 5G mGig access	Cat6 for many shorter runs; confirm site conditions	Existing cabling should be tested before reuse
10G copper	Cat6A is the safer planning baseline	Confirm channel length and switch port support
Outdoor, warehouse, or industrial area	Environment-rated cable	Check jacket, shielding, temperature, and pathway requirements
Patch panel to switch	Match the site cabling standard	Keep length, labeling, and category consistent

For procurement teams, “straight-through” is not enough information for a quote. The BOM should also state cable category, length, color, boot type, shielded or unshielded construction, indoor or outdoor rating, and whether the cable supports the expected PoE and speed requirement. If the order includes patch cords, transceivers, power cords, rack accessories, or replacement parts, check the Cisco cables and accessories category alongside the primary hardware.

Common Straight Through Cable Mistakes

Straight-through cable problems usually come from mixing wiring standards, using the wrong cable category, or treating a patch cord as interchangeable with installed cabling. These mistakes are easy to miss during procurement because many Ethernet cables look similar from the outside.

Mistake	Why it matters
One end is T568A and the other is T568B	Creates crossover, not straight-through
Assuming jacket color indicates cable type	Jacket color does not prove wiring pattern
Buying low-grade patch cords for PoE access points	Can cause power negotiation or link stability issues
Reusing old Cat5e for mGig or 10G without testing	May limit speed or create intermittent faults
Stocking crossover cables for modern access switches by default	Usually unnecessary with Auto-MDI/MDIX
Ignoring patch-panel wiring standard	Can create documentation and troubleshooting problems
Using damaged latch plugs in switch closets	Leads to loose connections and avoidable service calls

The safest operational habit is to label cables by purpose, keep patching records current, and test suspect links before replacing switches, access points, routers, or firewalls. A failed cable can look like a switch port problem if the troubleshooting process starts at the device instead of the physical link.

Straight Through Cable in Enterprise Network Buying

For small office networks, straight-through cable selection may look like a commodity purchase. In enterprise deployments, the decision affects installation speed, troubleshooting time, PoE reliability, and whether the cabling plant can support future access-layer upgrades.

Before ordering patch cords or approving a cabling BOM, confirm the following items:

1. Cable category: Cat5e, Cat6, Cat6A, or the project-specified type.
2. Termination standard: T568A-to-T568A or T568B-to-T568B.
3. Length: short patch cords for racks, longer runs only where appropriate.
4. Shielding: UTP for typical offices, shielded options where EMI or grounding design requires it.
5. PoE load: IP phones, cameras, APs, and high-power endpoints should not use poor-quality patch cords.
6. Environment: indoor office, plenum, riser, outdoor, warehouse, or industrial conditions.
7. Labeling: color and tag scheme for network operations, not as a substitute for testing.
8. Connected equipment: switch port speed, router/firewall interface, AP power class, and endpoint NIC speed.

For Cisco equipment projects, cabling assumptions should be checked with the rest of the BOM. Switches, routers, firewalls, access points, optics, power supplies, and accessories should be quoted against the same deployment context, especially when a project involves PoE endpoints, mGig access, WAN handoffs, or replacement hardware.

Common access requirement	Product category to review	Typical cabling relevance
Standard enterprise access closets	Cisco Catalyst 9200 switches	Common access-switch category for endpoint and PoE patching
Higher-feature enterprise access closets	Cisco Catalyst 9300 switches	Access-layer refresh category where uplink, stacking, mGig, and PoE planning matter
Small office and branch switching	Cisco Catalyst 1300 switches	Smaller office or branch category for fixed access switching

For wireless access projects, the endpoint side should also be checked against the selected Cisco wireless access points, because AP speed and power class affect both cable and switch-port planning.

Straight Through Cable Decision Table

Most Ethernet patching decisions can be reduced to the connection type. If the connection is between an endpoint or edge device and a switch, straight-through is normally the correct cable. If the connection involves older similar devices, check whether crossover is still required.

Connection	Use straight-through?	Notes
PC to switch	Yes	Standard LAN patching
Printer to switch	Yes	Common office access connection
IP phone to switch	Yes	Confirm PoE and voice VLAN design separately
Wireless AP to switch	Yes	Confirm AP power and mGig requirements
Camera to PoE switch	Yes	Confirm outdoor or industrial cable rating if needed
Router LAN port to switch	Yes	Common enterprise LAN edge connection
Firewall inside interface to switch	Yes	Common security edge connection
Modem or ONT to router WAN port	Usually yes	Port selection matters; cable pattern is usually straight-through
Switch to switch	Usually yes on modern gear	Auto-MDI/MDIX usually handles cable pairing
PC to PC	Usually no for legacy devices	Crossover may be needed if Auto-MDI/MDIX is not available

FAQ: Straight Through Cable