Arista Networks CAB-Q-4S-100G-2.5M Compatible 100G QSFP28 4 x 25G NRZ to 4 x 25G SFP28 NRZ Passive Copper Breakout Cable, 2.5m (8ft)

Product Highlights

• Compatible alternative to Arista Networks CAB-Q-4S-100G-2.5M
• 100G connectivity at 100Gbps
• Interface configuration: QSFP28 to SFP28
• Fixed length and part number: 2.5m (8ft), CAB-Q-4S-100G-2.5M
• Cable construction: Passive Twinax
• Conductor specification: 30AWG
• Maximum power consumption: ≤0.125W
• Minimum bend radius: 60mm

Specifications

Signal and Lane Configuration

The listed modulation format is QSFP28-4x 25G-NRZ SFP28-1x 25G-NRZ. Both host interfaces must be configured for the same aggregate rate and lane arrangement. A connector that fits mechanically does not by itself guarantee that the remote port supports this encoding or breakout mode.

Length Selection and Installation Planning

The 2.5m (8ft) version is useful when a two-metre run would leave insufficient working slack. Before installation, check the complete horizontal and vertical path so that CAB-Q-4S-100G-2.5M reaches both ports without tension at either connector.

Position Within the Length Range

CAB-Q-4S-100G-2.5M occupies the middle of this family between CAB-Q-4S-100G-2M at 2m (7ft) and CAB-Q-4S-100G-3M at 3m (10ft). It adds 0.5m over the shorter option for extra routing clearance, while the next longer version adds another 0.5m. Measure the managed path and choose this version when its reach is sufficient without creating the slack associated with the longer assembly.

High-Density Rack Integration

In a densely populated rack, connector access and airflow are part of the link design. Choose the shortest length that follows the managed path comfortably, avoid tight bundles around the connector housings and preserve room for latch operation. Where power consumption is listed, include every populated interface in the host thermal budget rather than assessing a single cable in isolation. For this assembly, the listed conductor specification is 30AWG; the minimum bend radius is 60mm; the stated power consumption is ≤0.125W; the jacket material is PVC (OFNR).

Power and Thermal Planning

The rated power consumption is ≤0.125W. Include this load in the host-port power and thermal budget, especially in densely populated switches. Maintain front-panel clearance and do not bundle the cable so tightly that it obstructs airflow around the connectors.

Cable Construction and Routing

This assembly uses 30AWG conductors, PVC (OFNR) jacket, minimum bend radius 60mm. These mechanical characteristics affect how the cable should be dressed behind the equipment. Avoid sharp edges, excessive ties and repeated tight bends close to the connector boots.

Network and Protocol Considerations

The intended application is 100G to 4x 25G Ethernet, Data Centers. Listed interface and protocol references include IEEE 802.3, QSFP28 MSA, SFF-8665. Confirm that the host firmware and port configuration support the same operating mode.

Breakout Port Mapping

The QSFP28 to SFP28 configuration divides the high-speed interface into multiple lower-speed connections. Verify the upstream lane assignment, downstream port speeds and breakout setting on the host before connecting the assembly. Each branch must attach to the correct remote interface.

Passive Copper Operation

A passive DAC has no separate optical conversion stage. Its low-power, low-latency operation is useful for short equipment links, but the assembly must remain within the length and signaling mode accepted by both hosts.

Quality Assurance and Packaging

Each assembly receives a visual connector inspection and functional link check before it is coiled and protected. Packaging is selected to avoid compressing the cable into a tight bundle, and optional rack-based labels help maintain an orderly installation when many identical interfaces are populated together. Standard protective packing is used by default, with project documentation arranged when requested.

Ordering Information

Provide the exact part number, length, quantity and target interface density. For multi-rack projects, list each length separately and identify any preferred carton grouping. Host model and software information can be included for a compatibility review before production or dispatch. This page’s fixed configuration is 2.5m (8ft); another length must be quoted under its corresponding part number.

Arista Networks Compatibility and Factory Testing

The assembly is evaluated for host recognition and stable link operation, with diagnostics checked where the interface provides them. This approach verifies more than electrical or optical continuity. Exact platform and firmware information remains valuable in high-density deployments because port mode and qualification policy can differ within the same connector family. The check includes link stability and diagnostic indications, followed by a final inspection of both ends.

Frequently Asked Questions

Shipping and Lead Time

Standard configurations normally ship within one to three working days, with production quantities confirmed at order stage. Delivery can be arranged by courier, air freight or sea freight, and goods may instead be handed to an appointed forwarder or shipped on the customer’s courier account.