PEX8734, PCI Express Gen3 Switch, 32 Lanes, 8 Ports

© PLX Technology, www.plxtech.com

Page 4 of 5

10Sep12; v1.0

Multi-Host Systems

In multi-host mode, the PEX8734 can support up to

three hosts at once. By creating three virtual switches,

the PEX8734 allows three hosts to fan-out to their

respective endpoints. This reduces the number of

switches required for fan-out, saving precious board

space and power. In Figure 7, the PEX8734 is being

shared by three different CPU cores (hosts) on three

servers, with each CPU core running its own

applications (I/Os). The PEX8734 assigns the endpoints

to the appropriate host and isolates them from the other

hosts. In Figure 7, the endpoints are assigned to the CPU

core of the same color.

Figure 7. Multi-Host System

Host Failover

The PEX8734 can also be utilized in applications where

host failover is required. In the below application

(Figure 8), two hosts may be active simultaneously and

controlling their own domains while exchange status

information through doorbell registers or I

The devices can be programmed to trigger fail-over if

the heartbeat information is not provided. In the event of

a failure, the surviving device will reset the endpoints

connected to the failing CPU and enumerate them in its

own domain without impacting the operation of

endpoints already in its domain.

Figure 8. Host Fail-Over