The PCIe fanouts and ICA SR fanouts are installed in locations LG01 - LG12 at the rear in the CPC drawers (see Figure 2-25 on page 69). The oscillator card (OSC) is combined with the Flexible Support Processor (FSP) and is in the front of the drawer. Two combined FSP/OSC cards are used per CPC drawer. 

The following types of fanout cards are supported by z15 servers. Each CPC drawer fanout slot can hold one of the following fanouts: 

GLYPH<SM590000> PCIe+ Gen3 fanout card: This dual-port copper fanout provides connectivity to the PCIe switch card in the PCIe I/O drawer. 

GLYPH<SM590000> Integrated Coupling Adapter (ICA SR): This two-port adapter provides coupling connectivity between z14 ZR1, z14, z13, and z13s servers, up to 150 meters (492 feet), @8 GBps link rate. 

## 4.4.1 PCIe+ Generation 3 fanout (FC 0175) 

An I/O connection diagram is shown in Figure 4-3 on page 162. 

The PCIe+ Gen3 fanout card provides connectivity to a PCIe+ I/O drawer by using a copper cable. One port on the fanout card is dedicated for PCIe I/O. This PCIe fanout card supports a link rate of 16 GBps (with two links per card). 

A 16x PCIe copper cable of 1.5 meters (4.92 feet) to 4.0 meters (13.1 feet) is used for connection to the PCIe switch card in the PCIe+ I/O drawer. PCIe fanout cards are always plugged in pairs and provide redundancy for I/O domains within the PCIe+ I/O drawer. 

PCIe fanout:  The PCIe fanout is used exclusively for I/O and cannot be shared for any other purpose. 

## 4.4.2 Integrated Coupling Adapter (FC 0172 and 0176) 

Introduced with IBM z13, the IBM ICA SR (FC 0172) is a two-port fanout feature that is used for short distance coupling connectivity and uses channel type CS5. For z15, the new build feature is ICA SR1.1 (FC 0176). 

The ICA SR (FC 0172) and ICA SR1.1 (FC 0176) use PCIe Gen3 technology, with x16 lanes that are bifurcated into x8 lanes for coupling. No performance degradation is expected compared to the coupling over InfiniBand 12x IFB3 protocol. 

Both cards are designed to drive distances up to 150 meters (492 feet) with a link data rate of 8 GBps. ICA SR supports up to four channel-path identifiers (CHPIDs) per port and eight subchannels (devices) per CHPID. 

The coupling links can be defined as shared between images (z/OS) within a CSS. They also can be spanned across multiple CSSs in a CPC. For ICA SR features, a maximum four CHPIDs per port can be defined. 

When STP FC 1021 is available, ICA SR coupling links can be defined as timing-only links to other z15, z14 ZR1, z14, and z13/z13s CPCs. 

These two fanouts features are housed in the PCIe+ Gen3 I/O fanout slot on the z15 CPC drawers. Up 48 ICA SR and ICA SR1.1 features (up to 96 ports) are supported on a z15 server. This configuration enables greater connectivity for short distance coupling on a single processor node compared to previous Z generations. 

