content_image/974311.jpg
As a result, two additional rack management ethernet switches are required to be installed in the base frame to provide the ethernet internal management network connections. 

This switch pair feature needs to be ordered with the expansion frame. Figure 2-27 shows the two additional network switches and the ethernet connections with an expansion frame and three connected iPDU sets. 

<img src='content_image/974311.jpg'>

## 2.6.3 Power Domains 

To provide redundant power, the iPDUs are organized in groups so called power domains. As shown on Figure 2-26 on page 57 and Figure 2-27 on page 58 the iPDUs on one side of the racks form a power domain. If you look at the rear of the storage system the iPDUs on left side of the racks is one (green) and the iPDUs on the right side of the rack are the other (yellow) power domain. 

Power redundancy is provided to each component such as CPCs, I/O enclosures, management enclosure and HPFE Gen2 flash drive enclosures with redundant PSUs by receiving its power for one of their PSUs from one power domain and the partner PSU from the other. 

It is important that each power domain is supplied from an independent power source. Both power domains should distribute to different AC main power sources (building power source or service entrance) by connecting their iPDUs AC inline connectors to the related circuit. 

