System Administration Guide: IP Services

Back-to-Back Link Aggregations

The back-to-back link aggregation topology involves two separate systems that are cabled directly to each other, as shown in the following figure. The systems run parallel aggregations.

Figure 6–5 Basic Back-to-Back Aggregation Topology

The figure is explained in the following context.

In this figure, device bge0 on System A is directly linked to bge0 on System B, and so on. In this way, Systems A and B can support redundancy and high availability, as well as high-speed communications between both systems. Each system also has interface ce0 configured for traffic flow within the local network.

The most common application for back-to-back link aggregations is mirrored database servers. Both servers need to be updated together and therefore require significant bandwidth, high-speed traffic flow, and reliability. The most common use of back-to-back link aggregations is in data centers.