| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 2372.1 | | SLINK::HOOD | Maine state bird: The black fly | Mon Jun 12 1995 14:35 | 4 |
| You can configure 7 Ethernets (one ThinWire and 6 flex channels) in the
DEChub 900 backplane.
There are 2 Token Rings in the DEChub 900 backplane.
|
| 2372.2 | 256...SEGMENTS...but..(grin) | PTOJJD::DANZAK | Pittsburgher � | Tue Jun 13 1995 00:32 | 8 |
| Of course...if each repeater port is a "Segment" and you can have 32
segments per repeater and 8 repeaters...then that is 256 Ethernet
segments "in the hub"....but across the BACKPLANE.......that's another
thing....(grin)
j
^--who stayed up late to think about that one.
|
| 2372.3 | Documentation error??? | ANGLIN::BERNDT | | Tue Jun 13 1995 11:00 | 11 |
| I guess yours truly is more than a little confused as I have read from
"the beginning" and can today document two of those written sources
that state twelve ethernets ON THE BACKPLANE. Further, other sources
state up to six Ethernets per "card" or device. Thus, when I place more
than one card (such as DECswitch 900EF or the new PORTswitch 900TP)
each of those cards talks to 6 Ethernets. It's just that I assumed they
could be 6 DIFFERENT Ethernets. For Example one PORTswitch on Ethernets
"1" thru "6" and the next PORTswitch on Ethernets "7" thru "12". If
that is not the case, this box is crippled in my opinion. ?????
Please explain ....
|
| 2372.4 | | NETCAD::HERTZBERG | History: Love it or Leave it! | Tue Jun 13 1995 11:20 | 19 |
| The DEChub 900 backplane uses "flex channels" to transfer information
between modules. Flex channels are so named because they can be used
in different ways by different modules. For instance, the way an
ethernet repeater uses the six wires of a flex channel to communicate
with another repeater or a switch is entirely different from the way
FDDI modules communicate using the wires.
To make a long story shorter, the current ethernet products, such as
the 900-family repeaters and PORTswitches, have the ability to attach
to only six of the flex channels in the hub. There are more flex
channels, but none of the current products can attach to them because
the required circuitry and wires are not on the module. Thus, only six
ethernets on the backplane (plus one more for the thinwire) with the
current product set.
This has been discussed in greater detail elsewhere in this conference.
Perhaps somebody can provide a pointer.
Marc
|
| 2372.5 | Read topics & replies in notes 506 & 740 for more on flex ch. | NETCAD::BATTERSBY | | Tue Jun 13 1995 12:38 | 7 |
| The following 2 notes and their replies have some further discussion
on the HUB 900 flex channels.
506 TENNIS::KAM 18-NOV-1993 1 DEChub 900: what is the flexibl
740 CGOOA::CRICK 17-FEB-1994 8 Can I use 15 Flex Channels?
Bob
|
| 2372.6 | Something else... | CGOS01::DMARLOWE | Wow! Reality, what a concept! | Tue Jun 13 1995 18:27 | 5 |
| To go beyond the 6 (or 7) Ethernets in a hub 900, see note 1735. You
can do some creative front panel connections to get 12, 18, or more
Ethernet LANs in a single hub.
dave
|
| 2372.7 | Thank you for the answers! | ANGLIN::BERNDT | | Tue Jun 13 1995 20:12 | 5 |
| Thank you all for the very helpful responses. Although I don't like the
answers I have received, I at least understand the "technical"
limitations. I will pursue this issue further with product
marketing/engineering. I wonder if 3COM is looking for any SE's...just
kidding! Ron
|
| 2372.8 | <-----RE: .7 Please elaborate as to what you didn't like :-) | NETCAD::BATTERSBY | | Wed Jun 14 1995 09:51 | 10 |
| Would you be willing to elucidate to us what it is you didn't like
about the answers you got? It might be helpful for all the firmware
and hardware HUB developers who try their best to provide helpful
dialogue in here if we got some constructive feedback on the
preferences of what users would like to see in our products for
features. Keep in mind when you "smother" us with your response that
any single product can't be all for everyone. Technically this is
near impossible.
Bob
|
| 2372.9 | The distinction... | ANGLIN::BERNDT | | Wed Jun 14 1995 10:58 | 28 |
| This is for .8:
1. I thought the response to my original post was swift, thorough and
definitely clarified my misconceptions. Again thank you all.
2. What I didn't like was the fact that each card cannot talk to any
"arbitrary" 6 LANs. My rationale, with a historic slant:
A. DEChub 900 introduced '93. Sales Update article in competitive
matrix states that it can support 14 Ethernets. That information is
then published in subsequent Competitive Handbook and current edition
of Networks Sales Kit, the later two disseminated both internally and
to VARs.
B. Subsequent "clarification" most anywhere you read that DEChub 900
modules (e.g. DECswitch 900EF) can "connect" to 6 backplane channels.
[I don't think we were saying a "specific" 6 at that point...or if we
did I wasn't clear on it.]
C. Many of us do demos using HUBwatch and start to create "point and
click" many Ethernets in the HUB. So my "premise" is still intact.
Unfortunately we didn't create the multiple (more than 6 Ethernets),
put in two 900EFs and try connecting to "1 -6" and "7-12". If we did,
the point of this whole thing would have become more clear.
So, basically the cards as stated in a previous reply to this note are
"hardwired" to 6 channels...period. When we say 6 channels we mean a
specific 6 not an arbitrary 6. That is the distinction that I don't
think we me, or at least I (and others) did not understand.
Other than that "issue" I love the DEChub family and think everyone
(developers) have done a great job...Ron
|
| 2372.10 | | STRWRS::KOCH_P | It never hurts to ask... | Wed Jun 14 1995 16:37 | 32 |
| From my perspective, re: .9, the author is exactly right. Currently,
the interface ASIC supports a MAXIMUM of 6 LANs. We need an NEW ASIC
which can support ALL 14 LANs (I've heard we've found a way to do even
more than this with the current etch and 14 was just a limit at the
time of announcement). We need 14 LAN support on all devices (bridges,
repeaters, etc.). Currently the per port switching repeaters are also
limited to 6 LANs.
In addition, we can't even do anything creative with the new per port
switching repeaters, because they also have a limit of 6 LANs. So, in
cases where we need more than 6 LANs, we have to do it in an non-hub
way to create the solution.
In addition, we have the ability to create 4 FDDI LANs in the
backplane. Without a hub FDDI switch, we really can't use them because
we need a GIGAswitch/FDDI on the outside to use all 4 LANs.
SET FRUSTATION_METER/LEVEL=HIGH
These requests have been sent to product managers for months. We never
get a response from them whether this is a good or bad. They tell us to
wait for CY 1996 products which are supposed to solve all our problems.
We need to take "little" steps with our products, not giant steps, but
engineering does not seem willing to do this for the field. However, in
engineering's defense, they probably aren't getting the information
they need. I've sent some of these memos, talked to people and it's
like a black hole. If engineers are willing to talk to me, look up my
ELF entry. I'll fly up to Littleton to talk and express the field's
view of what we need.
Ted Koch
NPB Field System Engineer
|
| 2372.11 | Message Received | NETCAD::HERTZBERG | History: Love it or Leave it! | Wed Jun 14 1995 17:07 | 11 |
| No need to look up ELF entries... engineering has heard this particular
message (more ethernets in the hub) loud and clear for some time now.
I'm sorry that you're frustrated, but don't think you're not getting
through. We are listening and we very much value input from the field,
such as input that we get from monitoring this conference.
The truth is that we have more things to do than people available to do
them. Another truth is that there is no small step we could take but
are holding back on for some reason which would solve this problem.
Marc
|
| 2372.12 | RE: Feedback has been heard...Thanks again for your input | NETCAD::BATTERSBY | | Wed Jun 14 1995 18:59 | 16 |
| Thanks Ron for your elucidation. When I first read your earlier
replies, I thought at first you were somehow dissapointed in the
content of the responses we provided. Now I realize that you were
in fact referring to the dissapointment in hearing our confirmation
of your concern that all the flex channels aren't truely "flexible"
as you had read in that early Sales Update article published back
in 93.
As Mark said, it isn't as if Engineering isn't hearing your concerns.
There are only so many oarsmen to row the oars, & we've been rowing at
a torid pace to get the products that now exist today in place.
The existing HUB 900MX today really provides migration between the
90 series products and the 900 series products, thus the primary
limitation on how "flexible" the backplane channels can be...today.
Bob
|
| 2372.13 | Still Confused | SNOFS1::KHOOJEANNIE | | Fri Jun 16 1995 03:25 | 14 |
| Further to the original question on how many Ethernets can be supported ...
I understand that the PORTswitch, DECswitch and PEswitch modules can
only connect to 6 IMBs, either 1 upper/5 lower or 6 on the lower connector,
and that the DECrepeater 90TS and FS can connect to the upper IMB.
Doesn't that mean that if we connect two DECrepeater 90TS/FS
together on the upper IMB, and a PORTswitch and a DECswitch together
on the 6 lower IMBs only, that we can use 7 IMBs for Ethernet?
Confused ...
Jeannie
|
| 2372.14 | Diagram time...... | NETCAD::BATTERSBY | | Fri Jun 16 1995 10:12 | 37 |
| Yes, but the Ethernet channel in the top, is a dedicated one, (the
Ethernet Thinwire), so it isn't included in the count of 6 channels
that are normally referred to in the documentation as "generic" Ethernet
channels. The flex channel in the top (Secretariat connector) cannot
be used by FDDI modules, but can be used by some of the recently
designed 900 series modules ( I don't know off the top which ones can
and cannot use the top flex channel). So the 14 channels in the bottom
connector can be "allocated" for Ethernet use and FDDI use.
Ok diagram time.....Below is the diagram of the DEChub 900 backplane.
Notice the labeling of the channels. Also notice the last two rows
in the Matrix are split 4 and 4. Thus the total number of Matrix
Flex channels are 14, 4 of which are 4 slots wide and 10 which go
across all 8 channels.
1 2 3 4 5 6 7 8
Ethernet Thinwire *----*----*----*----*----*----*----*
Flexible Channel *----*----*----*----*----*----*----* Secretariat
Token Ring A *----*----*----*----*----*----*----* Connector
Token Ring B *----*----*----*----*----*----*----*
--> *----*----*----*----*----*----*----*
| *----*----*----*----*----*----*----*
| *----*----*----*----*----*----*----*
| *----*----*----*----*----*----*----*
| *----*----*----*----*----*----*----*
14 flexible *----*----*----*----*----*----*----* Matrix
Channels *----*----*----*----*----*----*----* Connector
| *----*----*----*----*----*----*----*
| *----*----*----*----*----*----*----*
| *----*----*----*----*----*----*----*
| *----*----*----* *----*----*----*
--> *----*----*----* *----*----*----*
Bob
|
| 2372.15 | | NETCAD::DOODY | Michael Doody | Fri Jun 16 1995 17:13 | 15 |
| > I understand that the PORTswitch, DECswitch and PEswitch modules can
> only connect to 6 IMBs, either 1 upper/5 lower or 6 on the lower connector,
It is 1 upper/5 lower.
> Doesn't that mean that if we connect two DECrepeater 90TS/FS
> together on the upper IMB, and a PORTswitch and a DECswitch together
> on the 6 lower IMBs only, that we can use 7 IMBs for Ethernet?
No, the switch and repeaters can only use 5 of the lower IMBs.
It really is 6 ethernets plus the ThinWire.
-Mike
|