February, 2007
Station and Port Functions
4.1.2.2
Port Numbering
The PEX 8532 Port Numbers are 0, 1, 2, 3 (Station 0) and 8, 9, 10, 11 (Station 1). Ports 4, 5, 6, 7 and 12,
13, 14, 15 are reserved for future use. (Refer to Table 4-1 and Figure 4-3.) The Port Number and Device
Number are the same (in the Type 1 Headers) that map to all ports, with an exception for a non-zero
upstream port.
All downstream Device Numbers match their corresponding Port Number. For example, if Port 0 is the
upstream port, Ports 1, 2, 3, 8, 9, 10, and 11 are the downstream ports. The Device Numbers for the PCI-
to-PCI bridges implemented on the downstream ports are 1, 2, 3, 8, 9, 10, and 11, respectively. (Refer to
Figure 4-3.)
Any PEX 8532 port can be configured as the upstream port. The PCI-to-PCI bridge implemented on the
upstream port does not assume a Device Number – it accepts the Device Number assigned by the
upstream device. Generally, the upstream device assigns Device Number 0, according to the
PCI Express Base r1.0a.
Figure 4-3. PLX Port Numbering Convention Example (When Port 0 Is Upstream Port)
Port/Device 8
Port/Device 0
(Upstream
Port)
Port/Device 1
Port/Device 2
Port/Device 3
Port/Device 9
Port/Device 10
Port/Device 11
Internal
Fabric
PCI Express
Downstream
Station 1
PCI Express
Upstream
Station 0
Port 4
Port 5
Port 12
Port 13
Port 14
Port 15
Reserved
for Future
Expansion
Reserved
for Future
Expansion
Port 6
Port 7
ExpressLane PEX 8532AA/BA/BB/BC 8-Port/32-Lane Versatile PCI Express Switch Data Book
Copyright © 2007 by PLX Technology, Inc. All Rights Reserved – Version 1.6
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