What is a Direct Attach Copper Cable(DAC Cable)?

A Passive Direct Attach Copper Cable is also called DAC Cable, which is a type of copper-based networking cable commonly used for high-speed data transmission over short distances, particularly in data centers. It is a cost-effective and energy-efficient solution for connecting network devices like switches, servers, and storage within a rack or between adjacent racks.
Key Features of DAC Cables:

1. No Active Components: Passive DAC cable do not contain any electronics or signal-boosting circuits. They simply rely on the copper conductors to carry the signal from one end to the other. Because of this, they do not require external power.
2. Short Distance: They are typically used for short-range connections, usually up to 5–7 meters. The absence of signal amplification limits the effective transmission distance.
3. High-Speed Data Rates: Despite being passive, DAC cable can support high-speed data rates such as 10G, 25G, 40G, 100G, 400G,even to 800G, depending on the network technology and the cable's quality.
4. Cost-Effective: Lower cost compared to both Active Copper Cables (ACC Cable) and optical fiber cables(AOC Cable). Since there are no active components and no transceiver modules are required, passive DAC is a cheaper alternative for short-range connections.
5. Plug-and-Play: Passive DAC cable are easy to deploy, requiring no configuration or additional hardware. They function as simple"plug-and-play" devices.
6. Low Power Consumption: Since passive DAC cable have no active electronics, they consume zero power. This makes them energy-efficient and particularly useful in situations where power consumption is a concern.

Common Types of DAC Cables:

1. Passive DAC Cables

1).10G SFP+ DAC Cable: The 10G SFP+ DAC (Direct Attach Copper) cable is a cost-effective and energy-efficient cable designed for short-distance, high-speed 10 Gigabit Ethernet connections. It uses SFP+ (Small Form-factor Pluggable Plus) transceivers on both ends and provides plug-and-play connectivity without the need for additional transceivers or power.
2).25G SFP28 DAC Cable: A 25G SFP28 DAC (Direct Attach Copper) cable is a high-speed, low-latency, and cost-effective solution designed for 25 Gigabit Ethernet connections over short distances, typically within or between racks in data centers. It features SFP28 (Small Form-factor Pluggable 28) connectors on both ends and uses a copper twinax cable to transmit data. This type of DAC cable is commonly used in environments where high-bandwidth, short-range connections are needed between network equipment like switches, servers, and storage devices.
3).40G QSFP+ DAC Cable: The 40G QSFP+ DAC (Direct Attach Copper) cable is a high-speed, cost-effective cabling solution for short-distance 40 Gigabit Ethernet connections. It uses QSFP+ (Quad Small Form-factor Pluggable Plus) connectors on both ends and is commonly used for interconnecting network devices like switches, routers, and servers in data centers.
4).100G QSFP28 DAC Cable: The 100G QSFP28 DAC (Direct Attach Copper) cable is a high-performance, cost-effective cabling solution designed for 100 Gigabit Ethernet applications. It utilizes QSFP28 (Quad Small Form-factor Pluggable 28) connectors on both ends, enabling high-speed connections between networking devices such as switches, routers, and servers in data centers.
5). 200G QSFP56 DAC Cable: The 200G QSFP56 DAC (Direct Attach Copper) cable is a high-performance, cost-effective solution designed for 200 Gigabit Ethernet connections. It uses QSFP56 (Quad Small Form-factor Pluggable 56) connectors on both ends, allowing for high-speed data transmission between networking devices such as switches, routers, and servers in data center environments.
6). 400G QSFP-DD DAC Cable: The 400G QSFP-DD DAC (Direct Attach Copper) cable is a high-performance, cost-efficient cabling solution designed for 400 Gigabit Ethernet (400G Ethernet) connections. It uses QSFP-DD (Quad Small Form-factor Pluggable Double Density) connectors, which are specifically designed to support extremely high bandwidth requirements in modern data centers. These cables are ideal for short-distance, high-speed interconnects between networking devices like switches, routers, and servers.
7). 800G OSFP DAC Cable: The 800G OSFP DAC (Direct Attach Copper) cable is a high-performance solution designed for 800 Gigabit Ethernet (800G Ethernet) connections, primarily in high-density data center environments. The OSFP (Octal Small Form-factor Pluggable) connector is designed to support the demanding bandwidth needs of future-proof networking infrastructures, enabling fast, cost-effective, short-distance connections.
2. Breakout DAC Cables
1).40G QSFP+ to 4x10G SFP+ DAC Cable: This type of breakout DAC cable allows a 40G QSFP+ port to be split into four 10G SFP+ ports. This is commonly used in scenarios where a switch has a 40G uplink port but needs to connect to devices that only support 10G Ethernet.
2).100G QSFP28 to 4x25G SFP28 DAC Cable: This cable breaks out a 100G QSFP28 port into four 25G SFP28 ports. It is used in networks where 100G connections need to be split into multiple 25G connections to connect to lower-speed devices.
3).100G QSFP28 to 2x50G DAC Cable:This cable allows a 100G QSFP28 port to be split into two 50G connections, often used for higher-speed backbones.
4). 400G QSFP-DD to 8X50G SFP56 DAC Cable: The 400G QSFP-DD to 8x50G SFP56 DAC (Direct Attach Copper) cable is a specialized networking cable designed to split a single 400 Gigabit Ethernet (400G Ethernet) connection into eight 50G Ethernet connections. This cable configuration is commonly used in data centers and high-performance computing environments to provide flexibility and scalability in connecting various devices, such as switches and servers.
5).400G QSFP-DD to 4X100G QSFP56 DAC Cable: The 400G QSFP-DD to 4x100G QSFP56 DAC (Direct Attach Copper) cable is a specialized networking cable designed to split a single 400 Gigabit Ethernet (400G Ethernet) connection into four 100G Ethernet connections. This cable is commonly used in data centers and high-performance networking environments to efficiently connect multiple devices, such as switches and servers, from one high-speed port.
6).400G QSFP-DD to 2X200G QSFP56 DAC Cable: The 400G QSFP-DD to 2x200G QSFP56 DAC (Direct Attach Copper) cable is a specialized networking cable designed to split a single 400 Gigabit Ethernet (400G Ethernet) connection into two 200G Ethernet connections. This cable configuration is commonly used in data centers and high-performance computing environments to efficiently connect multiple devices, such as switches and servers, from one high-speed port.
7). 800G OSFP-DD-2x400G QSFP112 DAC Cable: The 800G OSFP-DD to 2x400G QSFP112 DAC (Direct Attach Copper) cable is a specialized networking cable designed to split a single 800 Gigabit Ethernet (800G Ethernet) connection into two 400G Ethernet connections. This type of cable is commonly used in data centers and high-performance computing environments, enabling efficient connectivity among devices like switches and servers from a single high-speed port.
 Use Cases:

• Intra-Rack Connections: Perfect for connecting devices within the same rack (for example, connecting a top-of-rack switch to a server).
• Adjacent Rack Connections: Can also be used to connect devices in adjacent racks within a data center.
• High-Speed Network Upgrades: Often used in high-speed networking environments like 10G, 25G, 40G, or 100G Ethernet environments, where short-distance, high-performance connectivity is needed.

Pros and Cons:
Pros:

• Cost-Effective: Much cheaper than both Active DAC and fiber optic cables.
• Energy-Efficient: No power consumption.
• Easy to Use: Plug-and-play, no need for additional components like transceivers.

Cons:

• Limited Distance: Maximum effective distance is typically 5–7 meters, which limits its use to short-range connections.
• No Signal Boosting: Without active components, it cannot maintain signal integrity over longer distances.

Passive DAC cables are an ideal solution for short-distance, high-speed connections in environments like data centers, where cost and power efficiency are important considerations. Their simple design and ease of use make them popular for intra-rack and inter-rack connectivity.
Several well-known brands manufacture DAC (Direct Attach Copper) cables, especially those designed for high-speed networking in data centers and enterprise environments. These brands are often associated with high-performance networking equipment. Here are some of the most famous DAC cable brands:
1. Cisco:

• Cisco is a leader in networking solutions and provides a range of high-quality DAC cables that are designed to work with its networking equipment, such as switches, routers, and servers. Cisco's DAC cables are widely used in data centers for 10G, 25G, 40G, and 100G Ethernet connections.

2. Arista Networks:

• Arista is known for its high-performance data center switches and offers DAC cables that ensure reliable, high-speed connectivity. They provide a variety of 25G, 40G, and 100G DAC cables compatible with their networking devices.

3. Juniper Networks:

• Juniper, another major networking hardware provider, manufactures DAC cables that complement their range of networking equipment. They are used in high-performance network environments for short-range connections in 10G, 40G, and 100G setups.

4. Mellanox (NVIDIA):

• Mellanox, which is now part of NVIDIA, is well-regarded for its high-performance networking solutions and provides a variety of InfiniBand and Ethernet DAC cables. These are commonly used in high-speed networking applications, including 100G and 200G Ethernet and InfiniBand.

5. Rollball:

• Rollabll  is a global supplier of networking products, offering a wide selection of 10G, 25G, 40G, 100G, 200G,400G and 800G DAC cables. Rollball products are known for being cost-effective and widely compatible with devices from other major networking brands like Cisco, Arista, and Juniper.

6. Brocade (Broadcom):

• Brocade, which is now a part of Broadcom, is known for providing networking products such as switches and storage networking equipment. Their DAC cables are frequently used in SAN (Storage Area Network) environments for 16G, 32G Fibre Channel, and Ethernet connectivity.

7. HP (Hewlett Packard Enterprise - HPE):

• HPE provides DAC cables as part of its comprehensive portfolio of networking solutions. Their DAC cables are commonly used with HPE switches, servers, and storage products in data centers and enterprise networks.

8. Dell EMC:

• Dell EMC provides high-performance DAC cables for its networking and storage equipment, particularly in 10G, 25G, 40G, and 100G Ethernet environments. Dell's DAC cables are optimized for use with its servers and networking switches.

9. Extreme Networks:

• Extreme Networks offers a variety of DAC cables for use with their high-performance switches and networking products, mainly for 10G and 40G Ethernet connectivity.

10. Finisar (II-VI):

• Finisar, now a part of II-VI, is a major player in optical communication technologies, but they also manufacture DAC cables for use in data centers and enterprise networks, particularly for Ethernet and InfiniBand connections..

These DAC cable brands are trusted by enterprises and data centers for providing robust, short-range, high-speed connections.