Difference between PCI bridge and PCI switch

[w***@gmail.com]

Hi,
I would appreciate of someone can explain the difference between
a PCI bridge and a PCI switch.
Is it true to say that PCI switch is historically newer and more new than
PCI bridge ?

Regards,
Kevin

[Jens Stuckelberger]

Hi,
I would appreciate of someone can explain the difference between a PCI
bridge and a PCI switch.
Is it true to say that PCI switch is historically newer and more new
than PCI bridge ?

I don't know the answer to your question, although a quick Google
search seems to return lots of probably relevant links. My question to
you would be: What do you mean that one is newer and more new than the
other?

[Clemens Ladisch]

Post by w***@gmail.com
I would appreciate of someone can explain the difference between
a PCI bridge and a PCI switch.

With good ol' PCI, a single bus can have many devices. A PCI bridge
is a device that connects multiple buses together, which is something
that was very seldom needed.

PCI Express looks, for software, very similar to PCI, but is electrically
a point-to-point connection, i.e., a PCIe bus has exactly two devices.

To connect PCIe with PCI, you need a PCI/PCIe or PCIe/PCI bridge.

If you have a single PCIe connector and multiple PCIe devices, you need
a PCIe switch. A single PCIe connection still is between exactly two
devices, so a PCIe switch consists of a (virtual) PCI bridge for the
upstream PCIe connection, and one (virtual) PCI bridge for each
downstream PCIe connection.


Regards,
Clemens

[Craig Ruff]

Post by Clemens Ladisch
With good ol' PCI, a single bus can have many devices. A PCI bridge
is a device that connects multiple buses together, which is something
that was very seldom needed.

PCI bridges can be much more common than you might think. Here is the output
from a motherboard that is about 3 years old.

% lscpi | grep 'PCI bridge'
00:01.0 PCI bridge: Intel Corporation 5520/5500/X58 I/O Hub PCI Express Root Port 1 (rev 13)
00:03.0 PCI bridge: Intel Corporation 5520/5500/X58 I/O Hub PCI Express Root Port 3 (rev 13)
00:07.0 PCI bridge: Intel Corporation 5520/5500/X58 I/O Hub PCI Express Root Port 7 (rev 13)
00:1c.0 PCI bridge: Intel Corporation 82801JI (ICH10 Family) PCI Express Root Port 1
00:1c.1 PCI bridge: Intel Corporation 82801JI (ICH10 Family) PCI Express Port 2
00:1c.2 PCI bridge: Intel Corporation 82801JI (ICH10 Family) PCI Express Root Port 3
00:1e.0 PCI bridge: Intel Corporation 82801 PCI Bridge (rev 90)
01:00.0 PCI bridge: NEC Corporation uPD720400 PCI Express - PCI/PCI-X Bridge (rev 06)
01:00.1 PCI bridge: NEC Corporation uPD720400 PCI Express - PCI/PCI-X Bridge (rev 06)
08:00.0 PCI bridge: Texas Instruments XIO2000(A)/XIO2200A PCI Express-to-PCI Bridge (rev 02)

[Satish Das]

It helped me today..Thank you for this simple explanation.

Thanks,
Satish

Post by w***@gmail.com
I would appreciate of someone can explain the difference between
a PCI bridge and a PCI switch.

With good ol' PCI, a single bus can have many devices. A PCI bridge
is a device that connects multiple buses together, which is something
that was very seldom needed.
PCI Express looks, for software, very similar to PCI, but is electrically
a point-to-point connection, i.e., a PCIe bus has exactly two devices.
To connect PCIe with PCI, you need a PCI/PCIe or PCIe/PCI bridge.
If you have a single PCIe connector and multiple PCIe devices, you need
a PCIe switch. A single PCIe connection still is between exactly two
devices, so a PCIe switch consists of a (virtual) PCI bridge for the
upstream PCIe connection, and one (virtual) PCI bridge for each
downstream PCIe connection.
Regards,
Clemens