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Since you "have several questions from a backplane/channel FDDI usage stand
point when 3 or more DECconcentrator are configured" and are "interested
in a DEChub 900MS technical description rather than a reference to Hubwatch",
I will attempt to answer your questions. For more details on exactly HOW
you set up the configurations via HubWatch, you will need to contact others.
Q1) What are the DECconcentrator 900MX configuration rules?
Please realize that that ANY FDDI connection between two adjacent
stations is actually POINT to POINT no matter where the stations are
in the configuration (tree or dual ring). This is a basic fact for
any vendor's FDDI products whether they are in a hub or not. The
backplane of the DEChub 900 is used to make these point to point
connections between DECconcentrators in the hub. One channel is
needed for each "fiber" connection. Since two "fiber" connections
are required between A and B ports (dual ring configuration) as well
as between M and S ports (tree configuration), TWO channels are
required to make the connection on the backplane between any two
DECconcentrators irregardless of the actual configuration. Technically
any type of configuration (dual ring, tree, or dual ring of trees)
could be supported in the DEChub 900 backplane but only a limited
subset of these options will be supported at FCS.
The following diagrams attempt to demonstrate the various types of
FDDI configurations that are possible in the hub:
NOTE: ONLY the TREEING configuration will be supported at FCS by
the firmware and HubWatch
Diagram #1: Treeing (Chained) Configuration:
Front Panel Ports
A M M M M B M M M M M M M M M M M M
| | | | | | | | | | | | | | | | | |
+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+
| CONC #1 | | CONC #2 | | CONC #3 |
+-+---------+-+ +-+---------+-+ +-+---------+-+
| | | | | |
Not +-------------+ +-------------+ M
Available M S M S
Backplane Ports
In this configuration, Concentrator #1 has a dual ring connection
via the front panel (ports #1 & #6) and ONE M-Port connection to
the backplane (a HARDWARE limitation does not allow the second
backplane port to be used in this particular configuration).
Concentrator #2 is treed off concentrator #1 via a backplane port
(S-port) and in turn concentrator #3 is treed off of concentrator
#2's backplane M-port. If concentrator #2 is removed/hot-swapped,
overtemperatures or stops talking to the Hub Management, the DEChub
Management will reconnect concentrator #3 directly to concentrator
#1 via the backplane.
Note: Chaining is probably a more accurate term than treeing in the
hub since we do not branch out into multiple paths but actually
string the concentrators together.
Diagram #2: Dual Ring Configuration:
Front Panel Ports
M M M M M B M M M M M M A M M M M M
| | | | | | | | | | | | | | | | | |
+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+
| CONC #1 | | CONC #2 | | CONC #3 |
+-+---------+-+ +-+---------+-+ +-+---------+-+
| | | | | |
M +-------------+ +-------------+ M
A B A B
Backplane Ports
In this configuration, all the concentrators connect directly to the
dual ring. Concentrator #1's front panel port #6 acts as the external
B-port connection to the dual ring and one of its backplane ports acts
as the A-port (the other backplane port can act as an M-port). With
concentrator #2, both backplane ports are used as the A/B connections
to the dual ring. Concentrator #3 has the B-port connection to the
dual ring via the backplane and the dual ring exits via port #1 that
is acting as an A-port.
Diagram #3: Dual Ring of Trees Configuration:
Front Panel Ports
M M M M M B A M M M M M M M M M M M
| | | | | | | | | | | | | | | | | |
+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+
| CONC #1 | | CONC #2 | | CONC #3 |
+-+---------+-+ +-+---------+-+ +-+---------+-+
| | | | | |
M +-------------+ +-------------+ M
A B M S
Backplane Ports
In this configuration, concentrators #1 & #2 connect directly to the
dual ring. Concentrator #3 is treed off of concentrator #2 (note:
additional concentrators could be treed off of either concentrator #1
or concentrator #3 M-ports) Concentrator #1's front panel port #6 acts
as the external B-port connection to the dual ring and one of its back-
plane ports acts as the A-port. Concentrator #2 has the B-port
connection to the dual ring via the backplane and the dual ring exits
via port #1 that is acting as an A-port. The second backplane port on
concentrator #2 acts as the M-port connection to the treed or chained
concentrator #3
Q2) How do you create a tree ring on the backplane?
I don't know what you mean by a "tree ring" unless you mean a
dual ring of trees. Diagram #3 shows how to create a dual ring of
trees configuration in the DEChub backplane but remember that
treeing or "chaining" (Diagram #1) is the ONLY configuration that
is supported at FCS. Support for other configurations such as a
ring of trees will occur in future releases of firmware/software.
Q3) How do you create multiple independent tree of rings on the backplane?
Just repeat configuration #3 (the ring of trees) twice and don't
interconnect them. You can support FDDI concentrators in all eight
slots of the DEChub 900 and interconnect them across the backplane
into a single FDDI network or multiple FDDI networks.
Q4) How do you create a DAS ring on the backplane?
You simply need to use the Dual Ring Configuration (Diagram #2)
above and connect the backplane port of concentrator #1 to the
backplane port of concentrator #3. See Diagram #4 below. Again
remember that treeing or "chaining" (Diagram #1) is the ONLY
configuration that is supported at FCS. Support for other types
of configurations such as a DAS ring on the backplane will occur
in future releases of firmware/software.
Diagram 4: Dual Ring in the Backplane
Front Panel Ports
M M M M M M M M M M M M M M M M M M
| | | | | | | | | | | | | | | | | |
+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+
| CONC #1 | | CONC #2 | | CONC #3 |
+-+---------+-+ +-+---------+-+ +-+---------+-+
| | | | | |
| +-------------+ +-------------+ |
| A B A B |
+---------------------------------------------------------+
B Backplane Ports A
Q5) How do you extend a DAS ring on the backplane to external DAS
devices?
See Diagram # 2 above for a DAS ring configuration in the backplane
but again remember that treeing or "chaining" (Diagram #1) is the ONLY
configuration that is supported at FCS. Support for other types of
configurations such as a DAS ring in the backplane will occur in
future releases of firmware/software.
Q6) If a DECconcentrator 900MX #1 is on a backplane SAS (not treeded) with 2
other DECconcentrators (#2, #3), then #1 fails ( or is hot swapped), can
#2 & #3 communicate while #1 is out of action? What does the Hub Manager
do with FDDI rings when a DECconcentrator module fails (or is hot swapped)?
I do not understand your question as it is worded. I don't see how
you have a SAS connection that is not treed - it seems to be a
contradiction. If you mean what happens when a concentrator in
a tree or chain is removed (hot swapped), then the DEChub Management
will detect the removal and reconnect the two neighboring concentrators
via the backplane to reform the chain/tree.
Looking at Diagram #5, if concentrator #1 fails or is hot swapped,
concentrators #2 and #3 can continue communicating with each other
but obviously will not be able to communicate to FDDI stations on the
DAS backbone since the physical link to that backbone (concentrator #1)
has been removed from the hub. If concentrator #2 is hot swapped,
Hub Management will automatically reconnect concentrator #3 to
concentrator #1 and communications can continue.
Diagram #5: Treeing (Chained) Configuration:
Front Panel Ports
A M M M M B M M M M M M M M M M M M
| | | | | | | | | | | | | | | | | |
+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+
| CONC #1 | | CONC #2 | | CONC #3 |
+-+---------+-+ +-+---------+-+ +-+---------+-+
| | | | | |
Not +-------------+ +-------------+ M
Available M S M S
Backplane Ports
NOTE: There is a "redundant root" configuration that will be
supported in a future release of firmware/software that will allow
redundant A/B connections out of the DEChub to the FDDI dual ring.
The Hub Manager will be able to do this where the hub has two
concentrators with DAS connections to the SAME dual ring and other
concentrators in the hub chain off one or the other concentrator.
If either of the "root" (DAS connected) concentrators is removed,
hot-swapped, overtemperatures, or stops talking to DEChub Management,
the Hub Management would automatically switch the chained concentrators
off of the failed root and onto the other root's chain. Refer to
Diagram #6: Concentrator #2 is chained/treed off Concentrator #1 while
Concentrator #4 is chained off of Concentrator #3. Both Concentrator
#1 and #3 have DAS (A/B) connections to the SAME FDDI ring/network.
If Concentrator #1 fails, then Concentrator #2 would be connected to
Concentrator #4, thereby creating the chain of #4 and #2 off of #3
acting as the root. (See Diagram #7)
Diagram #6: Redundant Root Configuration:
Front Panel Ports
A M M M M B M M M M M M A M M M M B M M M M M M
| | | | | | | | | | | | | | | | | | | | | | | |
+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+
| CONC #1 | | CONC #2 | | CONC #3 | | CONC #4 |
+-+---------+-+ +-+---------+-+ +-+---------+-+ +-+---------+-+
| | | | | | | |
Not +---------+ M Not +-------+ M
Available M S Available M S
Backplane Ports
Diagram #7: Configuration AFTER a Root Failure
Front Panel Ports
A M M M M B M M M M M M A M M M M B M M M M M M
| | | | | | | | | | | | | | | | | | | | | | | |
+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+
| FAILED ROOT | | CONC #2 | | CONC #3 | | CONC #4 |
+-+---------+-+ +-+---------+-+ +-+---------+-+ +-+---------+-+
| | | | | | | |
Not | | M Not +-------+ |
Available M | Available M S |
+-----------------------------------------------+
S M
Backplane Ports
Q7) Does the DECconcentrator 900MX have any port switching ( grouping
different ports on different rings)?
NO - the DECconcentrator 900MX does not support connections to
multiple FDDI rings/networks and therefore it does not make any sense
to have port switching. Just like the DECconcentrator 500, it has a
single MAC chip/address and connects to only ONE FDDI network.
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| What functionality do we have at FCS? I have heard that this product
now has a 150 day lead time! What is the problem?
I'm all for caution, but this is going to cause big problems in the
field! We need to be able to order and ship these devices NOW! If there
are limitations, give us a legal document for the customer to sign
acknowledging these limitations.
If we have a command line interface, who cares? If the limitation is
quantity 1 at each site in a DEChub 900 because it only supports A/B +
4 M ports, so be it. This is what my customers need. If I need a SLIP
connection to TELNET into the hub to configure it by hand, tell me.
I'll sell that as a service or give away 1 free configuation consulting
session or require the customer to buy a DS90TL to configure it until
HUBwatch is ready.
Tell me what concessions I have to make to get this product to my
customers!
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| This product has had a 150-day leadtime since it was announced, and it has
not been changed.
You need to talk with the product manager, Sharon O'Neill, about this product
to get a good status on where it is in the engineering cycle and when it
will ship as I don't have that information. Sharon can be reached at
DTN 226-5112 or on DELNI::ONEILL.
In general at least for my products, I can't just ship things now, or even
early for that matter, with some sort of legal document giving the customer
known restrictions as what I have now is just plain not ready. All the
functionality is not there, and won't be there till we finally get to FCS.
I realize that it's difficult for the field to hear that we're not ready
yet, but imagine the nightmares created by shipping something that doesn't
work yet or still has major known bugs or doesn't even have base-level
functionality. You can't put stuff like that on a customer's network, so
it doesn't help anyone to ship things that are not ready yet. If I could,
I'd start shipping stuff as I want the revenue and market-share just as much
as the next guy. But it's just not possible yet on my products that are still
under development. And although I continually beat on engineering to finish
the design and get the thing out the door, I also know they're working their
tails off to deliver.
Believe me, I'll ship as soon as I can, and I'll do whatever I can to get
protos for things like evaluations. But on some of my products, I'm just
not there yet.
Regards,
Cathy
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| I don't advocate shipping UNannounced products with customer letters.
However, if we do announce a product, we need to ship it within a
reasonable amount of time. 150 days is NOT reasonable.
I could see if these products were PROGRAM announced, but they were
PRODUCT announced. If so, 30-60 days is reasonable.
Are we saying that we are product announcing items which aren't fully
finished? If so, it allows our competitors to FUD our customers and
interrupts sales cycles and damage account control.
The announcement of the DECconcentrator 900MX essentially wipes out
sales of DECconcentrator 500 devices. Customers aren't going to buy
these since they are now "obsolete" in THEIR minds. If we want revenue
we should have a fire sale on DC500 products so customers feel they are
getting a "steal" when buying "obsolete" DC500 products. This would
help us to manage the revenue stream until full production of DC900
comes on line.
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