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## 4.3 PCIe+ I/O drawer 

The PCIe+ I/O drawers (see Figure 4-1) are attached to the CPC drawer through a PCIe cable and use PCIe as the infrastructure bus within the drawer. The PCIe I/O bus infrastructure data rate is up to 16 GBps. 

<img src='content_image/979985.jpg'>

PCIe switch application-specific integrated circuits (ASICs) are used to fan out the host bus from the CPC drawer through the PCIe+ I/O drawer to the individual I/O features. Maximum 16 PCIe I/O features (up to 32 channels) per PCIe+ I/O drawer are supported. 

The PCIe+ I/O drawer is a one-sided drawer (all I/O cards on one side, in the rear of the drawer) that is 8U high. The PCIe+ I/O drawer contains the 16 I/O slots for PCIe features, two switch cards, and two power supply units (PSUs) to provide redundant power, as shown in Figure 4-1. 

