HP Integrity rx8640 and HP 9000 rp8440 Servers Installation Guide

System Backplane to PCI-X Backplane Connectivity
The PCI-X backplane uses two connectors for the SBA link bus and two connectors for the high-speed
data signals and the manageability signals.
SBA link bus signals are routed through the system backplane to the cell controller on each
corresponding cell board.
The high-speed data signals are routed from the SBA chips on the PCI-X backplane to the two LBA
PCI bus controllers on the system backplane.
Clocks and Reset
The system backplane contains reset and clock circuitry that propagates through the whole system.
The system backplane central clocks drive all major chip set clocks. The system central clock circuitry
features redundant, hot-swappable oscillators.
PCI/PCI-X I/O Subsystem
The cell board to the PCI-X board path runs from the CC to the SBA, from the SBA to the ropes,
from the ropes to the LBA, and from the LBA to the PCI slots as shown in Figure 10. The CC on cell
board 0 and cell board 1 communicates through an SBA over the SBA link. The SBA link consists
of both an inbound and an outbound link with a peak bandwidth of approximately 11.5 GB/s at
3.2 GT/s. The SBA converts the SBA link protocol into “ropes.” A rope is defined as a high-speed,
point-to-point data bus. The SBA can support up to 16 of these high-speed bidirectional rope links
for a total aggregate bandwidth of approximately 11.5 GB/s.
There are LBA chips on the PCI-X backplane that act as a bus bridge, supporting either one or two
ropes for PCI-X 133 MHz slots and the equivalent bandwidth of four ropes for PCI-X 266 slots.
Each LBA acts as a bus bridge, supporting one or two ropes and capable of driving 33 MHz or
66 MHz for PCI cards. The LBAs can also drive at 66 MHz or 133 MHz for PCI-X mode 1 cards,
and at 266 MT/s for PCI-X mode 2 cards installed in mode 2 capable slots. When cell board 2
and cell board 3 are present, the cell boards attach to their own associated SBA and LBA chips
on the PCI-X board in the Server Expansion Unit.
18 HP Integrity rx8640 Server Overview