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FREQUENTLY
ASKED QUESTIONS
- What
is a Compact PCI Hub?
- What
is the advantage of using a Rear Transition Module slot?
- What
does the Hub connect to?
- What
does Carrier Class mean?
- What
does NEBS Compliant mean?
- Where
does it get its power?
- How
do I turn it ON and OFF?
- Is
it hot swappable?
- Can
I connect two cPCI hubs together for additional ports?
- What
level of reliability does the hub offer?
- Why
a Hub? Why not a Switch?
- What
is the difference between the Model DS12 and the Model DS12E?
- What
is Dual-Speed and how does it work?
- What
is a typical application?
What
is a
Compact PCI Hub?
This is a Hub-on-a-Card
for the Compact PCI and VME Chassis. It is designed to eliminate
the space traditional rack-mount hubs take up in a system. A cPCI
Hub inserts into a rear transition module slot to provide Ethernet
connectivity for a cPCI system.
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What
is the advantage of using a Rear Transition Module slot?
The
rear I/O mounting design provides a hub arrangement where Ethernet
cables are kept in the rear of the rack such that walkways are not
blocked and other front-insertion modules are easily accessed.
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What
does the Hub connect to?
A Front card, a Backplane? To maintain Carrier Class reliability,
the cPCI hub has been designed without any interconnection to the
Backplane. It is a "standalone card" unit, taking power
from an internal 12VDC power source via a small cable (not from
pins in the cPCI Backplane). This makes it usable in almost any
cPCI or VME system design, by simply mounting it in a 6U rear slot.
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What
does "Carrier Class" mean?
To GarrettCom, "Carrier Class" means that the unit (Magnum Blade
DS12) is rugged, reliable, low EMI noise, and will pass NEBS testing
when in a cPCI system environment. This term has been coined in
the telecommunications industry to designate products suitable for
the demanding applications in a CO, POP, etc.
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What
does "NEBS Compliant" mean?
It means it will pass NEBS testing in a system environment. "NEBS
certified", on the other hand, designates an item that has
passed NEBS testing as a separate stand-alone unit. Obviously, a
hub-on-a-card could not be NEBS tested individually.
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Where
does it get its power?
The MagnumBlade has an input power connector on the board, and uses
12VDC power (6.5 watts typical) from inside the Compact PCI chassis.
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How
do I turn it ON and OFF?
The hub is ON when power is applied, done by plugging a short power
cable into the connector at the bottom of the unit. Removing the
power cord turns the unit OFF.
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Is
it hot swappable?
Maybe. To service a Magnum Blade DS12, it has to be pulled out of
its Rear I/O slot, and the power connector on the DS12's board has
to be manually disengaged. (Normally the Ethernet cables are detached
before the card is pulled out, stopping the card from functioning).
By reversing this procedure, a replacement unit can be installed.
Is this "hot-swappable"? It depends on your definition.
Since hot-swappable cards normally do not have cables attached,
the classical definition would not apply here. Also, hot-swapping
in cPCI systems is usually reserved for Front Cards that plug into
the Backplane, so the concept would not be expected to apply to
Rear I/O modules. Note that designs with redundant Magnum Blade
DS12 cards can be implemented, preventing downtime for servicing
the DS12 modules.
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Can
I connect two cPCI hubs together for additional ports?
Yes. A manual up-link switch on the card (behind RJ-45 port #1,
at the top) provides the capability of cascading hubs together in
a system without crossover cabling. For example, a cascaded hub
may be another DS12 unit or an external Ethernet hub or switch.
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What
level of reliability does the hub offer?
The Magnum Blade DS12 has high availability, with over a 30-year
MTBF (287,864 hours MTBF @ 40°C calculated per Bellcore standards).
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Why
a Hub? Why not a Switch?
The advantages of a hub over switching technology are application
dependent. Hubs are preferred where timing is critical because hubs
introduce no packet-time delay. Also, all packets are assured of
being unconditionally sent to all connected ports. Hubs are robust,
simple, have low power consumption, low latency, and will move traffic
at full speed between any two ports at a time.
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What
is the difference between the Model DS12 and the Model DS12E?
The Model DS12 is a dual-speed auto-sensing 10/100Mb cPCI hub. The
Model DS12E is identical except that its speed is fixed at 100Mb/s,
no auto-negotiation can occur.
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What
is Dual-Speed and how does it work?
Dual Speed means that the twelve RJ-45 ports of the DS12 will function
at either 10Mb/s or 100Mb/s. An auto-sensing function is present
on the DS12 (not on DS12E) that allows each port to sense a link-whether
its operation is to be at 100Mb or 10Mb. If no auto-negotiating
device is connected, the default speed is 10Mb. A bridge is included
in the Blade hub to interconnect the two traffic domains of the
DS12. The bridge filters and selectively forwards packets to allow
the necessary packets to cross between 10Mb and 100Mb traffic domains,
enabling all users of either the 100 or 10Mb domains to communicate
with each other.
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What
is a typical application?
A Magnum Blade DS12 hub is typically used to interconnect and manage
multiple computers present in a cPCI system. These computers must
be present in such applications but also need reliable methods of
communication; a hub provides this robust functionality. Additionally,
the hub does not connect to the Backplane-another benefit for cPCI
system designs because precious bandwidth from the cPCI Backplane
will not be taken away by the hub. Having the ability to bring Ethernet
connectivity into a cPCI or VME system design without taking up
more than one slot significantly improves the design in these computing
applications.
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