| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 507.1 | No | CONSLT::BUZZELL | | Thu Nov 18 1993 10:54 | 14 |
|
The initial modules IE the DECrepeater 900TM can only have the
entire module connected to the ThinWire Ethernet and/or ONE of Six
Ethernets that can be created on the technology independennt channels.
Other modules with different functionality are planned and should
only be discussed with a customer under non-disclosure by a person
who is familiar with the products.
See the presentation at
NAC::LENAC_USER:[NETWORKS.PRESENT]900_PROD.PS
|
| 507.2 | Is it "and"? | HGRNCC::FARADAYCHONG | Faraday Chong@hgo 852-8053590 | Mon Nov 22 1993 04:38 | 17 |
| re .1
> The initial modules IE the DECrepeater 900TM can only have the
> entire module connected to the ThinWire Ethernet and/or ONE of Six
^^^
> Ethernets that can be created on the technology independennt channels.
Just to make sure I have it right.
Does this mean it can connect to the Thinwire Ethernet AND at the same
time to one of six technology independent channels?
Assuming the answer is yes, is this DECrepeater 900TM unique
capability? Or a capability in all 900 modules (provided they support
Ethernet of course)?
Faraday
|
| 507.3 | Which six? | SAC::HERBERT | Paul Herbert UK Govt A/cs | Mon Nov 22 1993 07:29 | 14 |
|
From the presentation mentioned in .1, certain future repeaters support :
"Each port or group of ports is assignable to one of six IMB Ethernet LANs
and/or the ThinWire Ethernet"
Does this mean "any six" of the available Ethernet channels? If so, this would
result in a max. of 7 channels (6 IMB + ThinWire) supported by a module and
another module in the hub could use a different group of 6 IMB channels?
Thanks,
Paul.
|
| 507.4 | | QUIVER::SLAWRENCE | | Mon Nov 22 1993 11:05 | 30 |
| I'm not sure I understand your question completely, but I will attempt
to clarify:
The DECrepeater900TM has 2 backplane ports:
1 Thinwire port - may be (and by default is) connected to the
Thinwire channel on the upper connector. Use
of this port counts as a repeater hop.
1 IMB port - may be connected to any 1 of 6 possible backplane
flexible channels (one on the upper connector and
five on the lower). Use of this port does _not_
count as a repeater hop.
By default, the hub manager does not connect the IMB port to anything;
you need to use HUBwatch (or, theoretically, another SNMP manager) to
connect it to an Ethernet backplane channel.
So the inference that there are (at present) at most 7 Ethernets on the
backplane is correct, but each module has the same 7 to choose from.
Since a backplane network segment serves no real purpose if only one
device is connected to it (if a system sends a packet and there is no
one on the net to hear it, did the packet really get sent?), and there
are only 8 slots, this is plenty.
As far as I'm aware, all currently planned Ethernet-capable devices
have the same backplane possibilities (the half height modules can only
use the upper connector, of course, so they have 2 possible
connections).
|
| 507.5 | Thanks but... | SAC::HERBERT | Paul Herbert UK Govt A/cs | Tue Nov 23 1993 05:47 | 18 |
| Thanks for the clarification.
You have answered my question - but I'm not sure that I like it :^)
We are looking for a cost effective way of connecting ~40 workgroups
of varying size to an FDDI backbone. The customer's requirement is to
isolate each workgroup's local traffic from the backbone.
We had thought of using repeater links between the workgroup hubs and
central hubs with DECrepeater 900FP modules - keeping workgroups
isolated by assigning ports to backplane channels. Then using
FDDI/Ethernet bridges to bridge the individual channels/workgroups
onto FDDI.
This solution would have considerably reduced the number of bridges
required. However, your reply infers that since we can only access 7
Ethernets per hub backplane, the number of central hubs will have to
be increased.
|
| 507.6 | | QUIVER::SLAWRENCE | | Wed Nov 24 1993 11:00 | 15 |
| Oh - you didn't say the FP; that is a slightly different story. Note
that my reply said it was for all currently available repeaters (which
does not include the FP).
*** FUTURES WARNING ***
The FP has _6_ backplane IMB ports (+ the Thinwire). Each pair of
front panel fiber ports can be mapped to a separate backplane port.
So yes, you could configure a central hub with a number of FP modules
and a WGE200 and do all the bridging there. That hub is still limited
to 6 IMBs (because each FP uses the same 6 backplane channels).
Don't ask about when this (or hubwatch support for configuring it) will
be available - I'm restricting myself to answering the _what_
questions, not the _when_ questions :-).
|
| 507.7 | FDDI -> ATM | VNABRW::PARGFRIEDER | | Wed Dec 01 1993 05:58 | 16 |
|
Thank you all for clarifying the repeater configurations.
In the presentation outlined in .1 the DEChub have 14 IMBs.
Why are only six of them useable?
What is the performance of 1 IMB ( Don't understand the maximum
trougput of the DEChub900)
If ATM modules are available in the future, will it be possible
to connect FDDI with ATM over bridges?
Thanks for help
Alfred
|
| 507.8 | | QUIVER::SLAWRENCE | | Wed Dec 01 1993 09:10 | 30 |
| > In the presentation outlined in .1 the DEChub have 14 IMBs.
> Why are only six of them useable?
Ethernet is a very cost-sensitive market; the extra drivers and
switching logic would be very expensive in both dollars and board real
estate (making other things more expensive). Add to that the fact that
it is a bus, so any number of slots can share a channel (unlike FDDI
which needs two channels for each slot->slot link, for example) and
6 starts to sound like a pretty good tradeoff.
> What is the performance of 1 IMB ( Don't understand the maximum
> trougput of the DEChub900)
An IMB is Ethernet == 10Mb/s
NOTE: An IMB is just one use to which the backplane signals may be put;
the hub architecture allows arbitrary groupings of backplane signals
for future hardware designs. For example, while FDDI uses the same
sets of signals as Ethernet, it uses them in a different way that
allows it to send 100Mb/s over the same 6 signals (1 'channel').
There are plans for modules that use the signals in other groupings
(not sets of 6 signals) to permit higher backplane speeds.
The backplane _really_is_ technology independant.
> If ATM modules are available in the future, will it be possible
> to connect FDDI with ATM over bridges?
Yes, but don't start selling it yet...
|
| 507.9 | Per port switching, limited to 6 IMBs ? | JOCKEY::GREENR | Curiosity Killed The Cat | Mon Dec 20 1993 12:21 | 3 |
| I believe we are planning to incorporate Per port switching UTP
repeaters within the hub in future. Can someone please confirm that
these will not be limited to just the 6 IMB channels.
|
| 507.10 | | QUIVER::SLAWRENCE | | Mon Dec 20 1993 12:26 | 2 |
| There are proposals for modules that would support more IMBs.
|
| 507.11 | More Ethernet support needed | TKTVFS::TSUJI_TA | TSUJI_TA | Fri Jan 07 1994 02:23 | 33 |
| > There are proposals for modules that would support more IMBs.
Is there any plan to support following features?
* Each repeater supports 6 Ethernet as it is.
(Each repeaters have per port switching Capability in this case.)
* HUB and HUBwatch support more than 6 Ethernet in a HUB.
* A couple of repeaters support more than 6 as a total like a picture below.
I hope this becomes soon available. Otherwise we need to prepare more than
two HUBs at each wiring closet because the customer is preparing 11 Ethernet
backbone segments believing that Digital's HUB is supporting 14 Ethernet
segments.
HUB A +-----++-----++-----+ +-----++-----++-----+ HUB B
|- R >||- R >||- R >| |- R >||- R >||- R >|
+--+--++--+--++--+--+ +--+--++--+--++--+--+
Ethernet 1 ---+----- | ---- | --- - - - - - - - ---+----- | ---- | - Ethernet 1
| | | | | |
Ethernet 2 ---+----- | ---- | --- - - - - - - - ---+----- | ---- | - Ethernet 2
| | | | | |
Ethernet 3 ---+----- | ---- | --- - - - - - - - ---+----- | ---- | - Ethernet 3
| | | |
Ethernet 4 ----------+----- | --- - - - - - - - ----------+----- | - Ethernet 4
| | | |
Ethernet 5 ----------+----- | --- - - - - - - - ----------+----- | - Ethernet 5
| | | |
Ethernet 6 ----------+----- | --- - - - - - - - ----------+----- | - Ethernet 6
| |
Ethernet 7 -----------------+---- - - - - - - - -----------------+-- Ethernet 7
| |
Ethernet 8 -----------------+---- - - - - - - - -----------------+-- Ethernet 8
Building wiring
|
| 507.12 | | QUIVER::SLAWRENCE | | Fri Jan 07 1994 14:37 | 24 |
| As understand it, there are people looking at making repeaters that are
capable of using more of the flexible channels (12), but will still
only be able to use 6 at a time. So the number of Ethernets in the hub
would be higher, but not the number any one repeater can connect to.
None of this will happen in a span _I_ would describe as 'soon'. If
you have a customer expecting 14 backplane Ethernets soon enough that
they are cabling for it now, then someone had better correct thier
expectations right away - it is not happening.
I don't understand the diagram you drew in -.1.
It looks to me as though you are assuming that you have the (coming)
repeaters with port grouping so that the modules connected (+) to the
backplane lans (1-8) are each supporting separate lans internally.
What are the "- - - - -" you have labeled 'Building wiring'? If they
are just wires then you have diluted or eliminated the benefit of
segmenting the LANs anyway - you have connected the collision domains.
FYI - The hub and HUBwatch already could handle more backplane
segments (go ahead - create a screenfull; you won't get errors until
you try to _connect_ more than 6); the restriction is from the
repeaters, and is a hardware restriction (mostly cost-motivated).
|
| 507.13 | | STRWRS::KOCH_P | It never hurts to ask... | Mon Jan 10 1994 16:55 | 8 |
| Does the DEChub 900 have an AUI to connect it to a LAN or does the
customer need to buy a device to interconnect this to their existing
LAN?
The customer is purchasing a DEChub 900 + DECbrouter 90 for their
existing LAN. To my knowledge and after reading the product
description, I suspect I need a device to connect to their existing
LAN.
|
| 507.14 | No network i/f on 900 | QUIVER::SLAWRENCE | | Mon Jan 10 1994 17:18 | 20 |
| > Does the DEChub 900 have an AUI to connect it to a LAN or does the
> customer need to buy a device to interconnect this to their
> existing LAN?
The DEChub 900 is technology neutral; it has no network interface
(except its OBM port).
> The customer is purchasing a DEChub 900 + DECbrouter 90 for their
> existing LAN. To my knowledge and after reading the product
> description, I suspect I need a device to connect to their existing
> LAN.
Assuming that nothing else they were going to put into it will serve,
that is correct.
If the existing LAN is thickwire, then probably the best bet is either:
DECrepeater 90FA (hub-based) DEFAR-MA $525
or
DECbridge 90 (hub-based) DEWGB-MA $2,455
|
| 507.15 | a few of the new repeaters also have AUI's | DELNI::GIUNTA | | Tue Jan 11 1994 14:29 | 6 |
| Or, if they can wait a few months, the DETTM (DECrepeater 900GM) and
DEFMI (DECrepeater 90FS) both have AUI's on the front panel. It all
depends what else they need besides the AUI connector, and when they
need it.
Cathy
|