PCI-Express over Cat6

  • Thread starter Thread starter Yousuf Khan
  • Start date Start date
daytripper said:
On Wed, 05 May 2004 16:10:36 GMT, "Yousuf Khan"
http://www.extremetech.com/article2/0,1558,1585024,00.asp?kc=ETRSS02129TX1K0000532

<yawn>

I love the bit about remoting HID devices.
Yeah, there's a high-throughput market to exploit...
Click to expand...

Maybe it's for the really, really, really fast typers? :-)

I guess in their haste to get a press release out they forgot that this sort
of job is already done by USB?

I'm sure they have much more important ideas in mind behind it, but none of
which really excite nor matter to typical home users. Things like clustering
interconnects or remote storage devices.
While the world pushes tighter integration, who does TI think is
going to pile on to a proprietary way to split a system into chunks?
Click to expand...

As I said, maybe they have some really big ideas, they just weren't smart
enough to make it sound exciting on a press release. :-)

Yousuf Khan
 
X-No-Archive: yes


Yousuf Khan said:
http://www.extremetech.com/article2/0,1558,1585024,00.asp?kc=ETRSS02129TX1K0000532

Maybe it's for the really, really, really fast typers? :-)

I guess in their haste to get a press release out they forgot that this sort
of job is already done by USB?

I'm sure they have much more important ideas in mind behind it, but none of
which really excite nor matter to typical home users. Things like clustering
interconnects or remote storage devices.


As I said, maybe they have some really big ideas, they just weren't smart
enough to make it sound exciting on a press release. :-)

Yousuf Khan
Click to expand...

Maybe we could one day get little modules with just the CPU and Gig-Ethernet
port to Add extra processing power.
 
daytripper said:
<yawn>

While the world pushes tighter integration, who does TI think is going to pile
on to a proprietary way to split a system into chunks?
Click to expand...

What can be used to take apart can also be used to put together. What
TI has done seems like some version of I/O that Intel was pushing...only
it's not Intel silicon, just like Infiniband isn't Intel silicon. How
will Intel react to this one: cut loose PCI-Express?

I've crossposted to comp.arch to see if I can't attract comments about
how real this is and what effects if might have outside the Intel/PC
marketplace.

RM
 
Robert Myers said:
What can be used to take apart can also be used to put together. What
TI has done seems like some version of I/O that Intel was pushing...only
it's not Intel silicon, just like Infiniband isn't Intel silicon. How
will Intel react to this one: cut loose PCI-Express?

I've crossposted to comp.arch to see if I can't attract comments about
how real this is and what effects if might have outside the Intel/PC
marketplace.

RM
Click to expand...

They are sending a 1X pci express over 4 pairs of CAT6 which is better than
CAT5 which 1000baseT uses.
They don't say how long the cable is. Ethernet uses 50 to 100 meters. 2-5
meters is a lot easier.
PCI-express is 2.5 Gb/s on the wire, GigE is 1.250 on the wire,
PCI express is working on cabling extensions. Intel is big on it. Why
would this make them upset?
1X PCI express is equivilent, roughly, to the 66MHz 32 bit PCI slot. Or
maybe to a 66 by 64 due to being duplex.
Many folks don't like to open the box to add stuff to their computer. This
is an alternative to things like firewire and USB2 as a way to add stuff.

del cecchi
 
Del said:
They are sending a 1X pci express over 4 pairs of CAT6 which is better than
CAT5 which 1000baseT uses.
They don't say how long the cable is. Ethernet uses 50 to 100 meters. 2-5
meters is a lot easier.
PCI-express is 2.5 Gb/s on the wire, GigE is 1.250 on the wire,
PCI express is working on cabling extensions. Intel is big on it. Why
would this make them upset?
Click to expand...

I probably should learn not to make remarks like that. Fat chance. ;-).

Since it's _TI_ silicon first to market, it would seem to have the
potential to interfere with IBM's plans to take over the server room
starting at the processor and moving outward.
1X PCI express is equivilent, roughly, to the 66MHz 32 bit PCI slot. Or
maybe to a 66 by 64 due to being duplex.
Many folks don't like to open the box to add stuff to their computer. This
is an alternative to things like firewire and USB2 as a way to add stuff.
Click to expand...

I dunno. I know even less about expansion bus protocols than I do about
most other things. Is there anything you can do with any available
out-of-the box interconnect that you can't do with lower latency using
PCI-Express? Limited bandwidth and distance, to be sure, but how could
you beat the latency?

RM
 
Robert Myers said:
I probably should learn not to make remarks like that. Fat chance. ;-).

Since it's _TI_ silicon first to market, it would seem to have the
potential to interfere with IBM's plans to take over the server room
starting at the processor and moving outward.


I dunno. I know even less about expansion bus protocols than I do about
most other things. Is there anything you can do with any available
out-of-the box interconnect that you can't do with lower latency using
PCI-Express? Limited bandwidth and distance, to be sure, but how could
you beat the latency?

RM
Click to expand...

IB and PCI-Express should be pretty comparable. (PCI express isn't out of
the box yet)
Ethernet with RDMA and hardware offload is in the same ballpark.
Rapid I/O, Fibre Channel, are contenders depending on task.

Is latency a big deal writing to a disk or graphics card?
 
Distributed systems, distributed redundant systems, or perhaps there
are some really hot noisy graphics cards planned that cook in BTX
environment and thus need to be relocated to a different... building :-)

USB is a nice idea - but it's implementation seems somewhat variable,
with reliability issues from chipsets to firmware. HDs can vanish on you,
scanners can stop working, printers can sometimes refuse to be seen.
Self power seems particularly marginal with blown or pico fuse resets.

Latency could be interesting tho - Myrinet isn't exactly cheap.

IT industry seems to be creating a lot of Beta v VHS right now.
 
Robert Myers wrote:

Since it's _TI_ silicon first to market, it would seem to have the
potential to interfere with IBM's plans to take over the server room
starting at the processor and moving outward.
Click to expand...

Grotesque slip:
Since it's _TI_ silicon first to market, it would seem to have the
potential to interfere with ->Intel's<- plans to take over the server
room starting at the processor and moving outward.
Click to expand...

I'm sure that IBM doesn't feel that it needs to take over anything. ;-).

RM
 
Dorothy Bradbury said:
Distributed systems, distributed redundant systems, or perhaps there
are some really hot noisy graphics cards planned that cook in BTX
environment and thus need to be relocated to a different... building :-)

USB is a nice idea - but it's implementation seems somewhat variable,
with reliability issues from chipsets to firmware. HDs can vanish on you,
scanners can stop working, printers can sometimes refuse to be seen.
Self power seems particularly marginal with blown or pico fuse resets.

Latency could be interesting tho - Myrinet isn't exactly cheap.

IT industry seems to be creating a lot of Beta v VHS right now.
Click to expand...
Unless they pretty radically change (extend) the pci-express physical
layer and probably some stuff about the architecture across the room is
about what you can hope for. And the room better not be too big.

del cecchi

PS Implementations are always variable, unless there is only one.
 
Unless they pretty radically change (extend) the pci-express physical
layer and probably some stuff about the architecture across the room is
about what you can hope for. And the room better not be too big.
Click to expand...

Well, hell, even I will give them more credit than that. There's no real need
to change the PCI Express architecture to do what TI's (probably) doing, just
send an n-bit wide link to a bridge device and you're good to go nuts bolting
on devices until you've squeezed that link to the last bps.

Physical layer changes are likely quite modest - just enough to get them a
patent of some kind (the article did imply it was somehow proprietary). otoh,
"proprietary" is unlikely to fly far as an io interconnect. Nobody likes
paying tribute, and afaict there's no obvious need to stray from the
soon-to-be-well-trod path (PCI-X Mode 2 is an utter non-starter now - Intel is
likely going to quietly let it die without ever selling a product with it -
sending the hoards directly to PCI Express) to build rather large systems full
of IO devices.

As for using TI's little scheme for desktop/HID devices instead of USB: it is
to laugh. USB 2.0 fast mode is way overkill for HIDs as it is, it's open and
cheap to implement, brings (modest) power to the devices (not mentioned in
this Cat6 scheme) and from a fair size (but admittedly not huge) sample of
diverse USB 1 & 2 devices in our labs, appears quite mature (finally, yes ;-)
PS Implementations are always variable, unless there is only one.
Click to expand...

lol

Still, not quite as humorous as using "lower latency" in the same sentence
with "HID devices"...

/daytripper
 
Dorothy said:
Distributed systems, distributed redundant systems, or perhaps there
are some really hot noisy graphics cards planned that cook in BTX
environment and thus need to be relocated to a different... building
:-)
Click to expand...

I can also see fairly interesting home use for PCI-E over Cat6: home theatre
applications. Sending the Dolby/DTS sound *and* the HDTV video over the same
wire basically. :-)
USB is a nice idea - but it's implementation seems somewhat variable,
with reliability issues from chipsets to firmware. HDs can vanish on
you, scanners can stop working, printers can sometimes refuse to be
seen. Self power seems particularly marginal with blown or pico fuse
resets.
Click to expand...

But more than good enough for an HID interface.
IT industry seems to be creating a lot of Beta v VHS right now.
Click to expand...

Intel was even bellowing about trying to combine USB and WiFi together to
form Wireless USB which it expects will take on Bluetooth, except be faster
and work over greater distances.

Yousuf Khan
 
Judd said:
I'm thinking office... not so much motherboard. It's application could be
far reaching from an office standpoint, but cabling would need to be
upgraded infrastructure-wise.
Click to expand...

I seriously doubt that despite the fact that it's a Cat6 wire, it will not
likely go the distances that you typically can take an Ethernet out to. It's
likely only using the cabling of Ethernet without the actual Ethernet
protocol. They're likely going to limit the distances that the cable can
travel in this application.

Yousuf Khan
 
In comp.sys.ibm.pc.hardware.chips Yousuf Khan said:
I seriously doubt that despite the fact that it's a Cat6 wire, it will not
likely go the distances that you typically can take an Ethernet out to.
Click to expand...

Bingo! Ethernet twisted-pair wire isn't so special, its more
the balanced signalling used. Signal+ paired with Signal-.

Ethernet 100baseTX was running 100 MHz across 100m of wild
country at a time when motherborad designers had trouble with
running 50 MHz across 20 cm of multi-layer PCB. But mobo
signals aren't balanced and that gives all sorts of problems.
Balancing the signals would double the AC pincount.

AFAIK, no PCI varient uses balanced signalling, so really
won't benefit from Cat6. IIRC, there was a oddball SCSI
that did used balanced signals.

-- Robert
 
AFAIK, no PCI varient uses balanced signalling, so really
won't benefit from Cat6. IIRC, there was a oddball SCSI
that did used balanced signals.
Click to expand...

HVD did I think, which could run very long distances.

Characteristics of Cat5/6 cable soon change if you abuse it,
so distance aside I don't think it's for typical office environments.
 
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