The gateway to more bandwidth with less fiber – optical aggregation and breakout

How transceiver aggregation and breakout work

First, pluggable transceivers are connected to a router or switch to send data streams over optical links. These transceivers are typically connected to a transponder that aggregates multiple inputs, such as four times 100G, into a single higher-capacity signal, such as 400G. The resulting aggregated signal, 4x100G, is then transmitted over a single wavelength, reducing the need for additional fiber and optimizing network efficiency.

Possible optical aggregation and breakout combinations

Aggregation and breakout formats depend on transceiver form factors, data rates and lane availability. The input speed must align with the output transceiver’s capacity. For example, four 25G SFP28 connections can be aggregated into 100G using a QSFP28 transceiver. In transceivers with more lanes, such as QSFP-DD, additional aggregation formats are made possible, such as 8x100G to 800G.

Breakdown of common aggregation formats

See more aggregation and breakout combinations in “The Essential Transceiver Selection Guide”.

Backwards compatibility across SFP-QSFP generations generally allows for native breakout applications, such as 400G QSFP-DD to four 100G QSFP28 links. However, breakout cables can also be used as a workaround for form factors without backwards compatibility, such as OSFP. This means that a wide variety of combinations are possible beyond the most common discussed in this article. Whether you aggregate using transponders or not also makes a difference.

The benefits of transponder-based aggregation

While aggregation has traditionally required a transponder or muxponder, newer routers and switches are now incorporating built-in aggregation capabilities utilizing Link Aggregation Group (LAG). However, transponders remain the standard solution in most use cases, offering advantages over LAG in fiber utilization, multi-vendor compatibility and long-distance transport. 

Unlike LAG, which distributes traffic across multiple links at the Ethernet layer, transponders aggregate signals optically into a single higher-speed wavelength, maximizing fiber efficiency. This approach ensures seamless interoperability in multi-vendor environments, avoiding potential issues with vendor-specific LAG implementations. Additionally, transponders support long-haul transmission with integrated forward error correction (FEC) and DWDM capabilities, making them the preferred choice for scalable, high-performance aggregation.

Top 3 benefits of transceiver aggregation and breakout

Aggregation maximizes bandwidth utilization without major upgrades. For instance, if your router supports up to 100G, a transponder with aggregation capabilities lets you combine four QSFP28 transceivers (100G each) into a single 400G QSFP-DD transceiver over one fiber pair. This way, aggregation enables several benefits, including:

• Optimized fiber utilization without the need for additional infrastructure, lowering both capital and operational expenses while improving bandwidth utilization. 
• Increased capacity with access to higher bit rates than supported by the router or switch with transponder-based aggregation. 
• Scalability with easy upgrades of aggregated transceivers to higher bit-rate optics without other changes to your setup, e.g. from 4x25G to 4x100G.

The vast potential of 800G aggregation

By doubling the speed of 400G, 800G opens up aggregation of more high-speed 100G links than ever before. This is why the strongest trending 800G aggregation format is 8x100G. 2x400G will also be popular for use cases where doubling down on two ultra-high-speed 400G links adds the most value. 4x200G is also possible with 800G.

Scenario: Aggregating 8x100G for seamless and redundant enterprise DCI

A large enterprise or an internet exchange with multiple data centers across a metro area deploys a redundant ring network architecture to ensure high availability and continuous operation. By aggregating eight 100G links from each data center into a single 800G signal, the enterprise minimizes fiber usage while maintaining scalability and redundancy. This setup allows the enterprise to leverage existing 100G-capable hardware while achieving the capacity needed for data replication, disaster recovery and critical applications.

Scenario: Aggregating 2x400G for cost-effective scaling in regional networks

A communications service provider connects core and aggregation sites across rural and metro areas with high-capacity backbone links. By aggregating two 400G signals, the provider doubles capacity over a single wavelength, reducing fiber costs and simplifying network management. This approach efficiently supports both enterprise and residential customers, ensuring high-capacity transport without requiring extensive upgrades to existing infrastructure that supports up to 400G.