Appendix A: Additional Guidelines and Equipment Details
65
Dell EMC PowerEdge MX
Networking Architecture Guide
conversion to FC signaling, the 32GFC interfaces are mapped to four 25 Gbps lanes. With
each lane operating at 25 Gbps, not 28 Gbps, the result is rate limited 32 Gb FC.
Figure 57. 4x 32 Gb FC breakout mode, rate limit of 25 Gbps
While each 32 Gb FC connection is providing 25 Gbps, the overall FC bandwidth available
is 100 Gbps per unified port group, or 200 Gbps for both ports. However, if an application
requires the maximum 28 Gbps throughput per port, use the 2x 32 Gb breakout mode.
This mode configures the connections between the NPU and the FC ASIC as shown in
Figure 51.
Figure 58. 2x 32 Gb FC breakout mode
In 2x 32 Gb FC breakout mode, the MX9116n FSE binds two 50 Gbps links together to
provide a total of 100 Gbps bandwidth per lane to the FC ASIC. This results in the two FC
ports operating at 28 Gbps. The overall FC bandwidth available is 56 Gbps per unified
port, or 112 Gbps for both. Compared to the 200 Gbps using 4x 32 Gb FC.
Note: Rate limited ports are not oversubscribed ports. There is no FC frame drop on these
ports and buffer to buffer credit exchanges ensure flow consistency.
Spanning Tree Protocol recommendations
