Specifications

Starting With StarFabric:The StarFabric Connectivity Guide 29
StarFabric Applications
Sample Application - PCI Scalability
Next-generation PCI expansion is one of the most common needs in the industry. If
you need to increase PCI slot count, but also have concerns about increasing band-
width speeds with a larger number of PCI slots, while retaining the value of your
original investment in legacy PCI or CompactPCI hardware, StarFabric may be the
solution for you.
Without StarFabric...
PCI-to-PCI bridging is one way to increase the number of PCI slots in your topol-
ogy, as shown in Figure 8.
FIGURE 20. PCI Expansion Before StarFabric
PCI-to-PCI bridges add more buses to the topology and thereby increase the slot
count. However, this solution doesn’t increase the available bandwidth on your bus
system. Bandwidth is divided up into smaller chunks as more devices and buses are
added and higher speeds mean support for fewer slots. Understandably, latency and
scalability become issues in this topology.
Top bandwidth for PCI is about 533 MB/s,
not counting the overhead for protocol soft-
ware. But more commonly PCI throughput
runs at about 132 MB/s. Typically, higher
speed PCI buses support fewer
expansion slots