| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 1981.1 | DS900EF can use SMF via HUB-one MX | STKHLM::WEBJORN | Gullik Webj�rn Network Advisory | Thu Mar 14 1996 10:33 | 6 |
|
If you use the HUB-one MX, you can add a SMF pmd to one or two of
the FDDI ports. Is the customer running FDDI at the other site ?
Gullik
|
| 1981.2 | Only link between remote and local site is FDDI | 43406::GREID | All that is, was and will be... | Thu Mar 14 1996 11:27 | 9 |
| Gullik,
I understand that they plan to have the SMF route to another
DECSwitch 900 EF at the remote site, providing UTP at the remote
side and the local DECSwitch here will have the SMF converted to
AUI and then connected into the Switch. A DECrepeater 900 providing
UTP to the space also connected to the local Switch.
Giles.
|
| 1981.3 | | STRWRS::KOCH_P | It never hurts to ask... | Thu Mar 14 1996 12:26 | 10 |
|
You're mixing your metaphors here.
If you want to create an FDDI ring between two DECswitch 900EFs,
they'll have be standalone. If they are, purchase 2 DEChub One MX power
supplies and two SMF PMDs (DEFXS-BA) and the connect the two power
supplies togther with the SMF. This gives the customer a single FDDL
ring with 6 Ethernet ports at each site.
|
| 1981.4 | More on mixing metaphors..... | NETCAD::BATTERSBY | | Thu Mar 14 1996 12:35 | 7 |
| To follow Teds thread Giles, I think the AUI to fiber device you
are thinking of is the DEFLM fiber-optic to AUI 10baseFL Transceiver.
The fiber side of this device with ST connectors on it *will not*
work with FDDI. The fiber media intended for this device is 10baseFL.
The way to connect 2 EF's is as Ted described.
Bob
|
| 1981.5 | Clarification of Topology | 43406::GREID | All that is, was and will be... | Fri Mar 15 1996 05:08 | 34 |
| Ok,
This is getting confusing now, heres the topology of the link
setup, all comments welcome.
Ethernets
+-+ Converter +-+ Ether'
--------| | +-+ +-+ UTP +-+ | |
--------| |----| |-----------| |----[]-----------[]----| |----| |-------
--------| | +-+ +-+ SMF +-+ | |
+-+ Zenith Zenith Zenith +-+
DS900EF Modem Modem Modem DS900EF
(remote) (local)
This is part of the configuration I have been shown, I have no idea
what the Zenith Modems are but I will find out. Basically the customer
(which is also the Internet provider Telecential), believes they can
use the converters to change SMF into UTP or 10Base5 to then connect
into the DECSwitch. The AUI 10BaseFL is not the DEC one but a third
party one by the looks of it, which "converts AUI Ethernet output from
an Ethernet PC Adaptor card or terminal server into 10BaseFL optical
ethernet signal, the single mode version extends the distance to 6km."
I think they are getting the wrong impression here, and that in fact
the fibre is just being used to link the DECSwitches, not meant as a
proper ring and probably the OneHub MX with SMF mod pmds is the way
forward.
Thoughts ?
Giles.
|
| 1981.6 | | 43406::GREID | All that is, was and will be... | Fri Mar 15 1996 05:10 | 7 |
| A slight mistake in the previous note should not have three Zenith
modems in but two with the one on the extreme right not being a Zenith
modem but just the converter.
Sorry for any confusion,
Giles.
|
| 1981.7 | the problem is really long-haul ethernet over fibre | MARVIN::RIGBY | No such thing as an alpha beta | Fri Mar 15 1996 10:05 | 47 |
| I've been involved peripherally with the project that Giles refers to.
The company is a cable service provider and, as such, has large amounts of
single-mode fibre all over the town. They need to link a number of sites which
have Ethernets together and at least one site that has an FDDI backbone.
One problem they have is that the distances involved are reasonably large, upto
10km and they have little space anywhere to have any equipment between these
points.
The bandwidth they need between the sites is only 10Mb so they would be happy
with an ethernet but none of the ethernet-over-fibre adapters could cope with
the distance because of the flight time. They don't want to go to FDDI over the
long-haul because either it means they have to have the long-hauls in their
rings (using something like the mx900 with some SMFs and some MMFs) or have an
FDDI-FDDI bridge or router. They are worried about reliability of the backbone
with the former and cost with the latter.
This project is very cost and lead-time sensitive, they would like cheap kit to
solve their problem yesterday!
How we'd proposed setting up their main site was a group of 900EFs on the ring
with UTP directly connected servers and UTP repeaters to get the dozens of PCs
connected up. This all works fine on the one campus but then the remote sites
are a bit of a problem.
Don't worry about the Zenith modems, they are broadband ethernet 'repeaters'.
So, the whole setup is:
remote ethernet -- broadband -\
remote ethernet -- broadband -- head station - ethernet--..........
remote ethernet -- broadband -/ :
:
:10km SMF
:
:
900EF :
/ \ :
PC -utp- repeater-900EF=fddi=900EF-ethernet--......................
PC -utp-/ /
PC -utp-\ /
PC -utp- repeater-/
PC -utp-/
and the most important question is, what connects those two ethernet ports?
|
| 1981.8 | But it's so simple... | STKHLM::WEBJORN | Gullik Webj�rn Network Advisory | Mon Mar 18 1996 06:11 | 8 |
|
Even if the customer only needs 10 Mbit, maybee the simples and most
cost effective way is to actually use the FDDI ports as a simple fiber
link. No extra equipment is nessecary, and the fiber plugs straight
into the DS900. Range will be 40 km or ~ 25 miles with no intervening
equipment.
Gullik
|
| 1981.9 | Or maybee PEswitch | STKHLM::WEBJORN | Gullik Webj�rn Network Advisory | Mon Mar 18 1996 06:15 | 9 |
|
Also, forgot, if you are chasing costs, if the customer only needs a
few addresses 'at one end' the PEswitch 900 in a DecHUB one MX is even
lower, but reduces 'remote mac addresses' to 64.
You could still have SMF pmd at the back....
Gullik
|
| 1981.10 | 2x900ef just to get longhaul ethernet? | MARVIN::RIGBY | No such thing as an alpha beta | Mon Mar 18 1996 09:10 | 31 |
| Gullik,
are you therefore proposing...
remote ethernet -- broadband -\
remote ethernet -- broadband -- head station - ethernet--900EF(SMF)
remote ethernet -- broadband -/ :
:
:10km SMF
:
:
900EF :
/ \ :
PC -utp- repeater-900EF=fddi=900EF-ethernet--............900EF(SMF)
PC -utp-/ /
PC -utp-\ /
PC -utp- repeater-/
PC -utp-/
Can't live with a 64 address restriction. Can't use one of the 900EFs on the
main campus because there are all connected to the campus FDDI already. Two
900EFs seems a remarkably expensive way of connecting an ethernet over 7.5km.
The 900EF at the headstation would be easy to justify, there was one there in
the upgrade plan anyway (or at least a PS900> for the intended multiple
broadband LANs, a concentrator at the main campus might then be a better
solution to get 100Mbps to it from the head station.
The ideal solution would probably have been a two port ethernet bridge with SMF
on one side capable of operating Full-Duplex point to point. If such a beast
existed I wonder how its cost would compare to a 900EF.
|