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Another cabling question - BNC

Posted on 1998-05-12
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Last Modified: 2013-12-23
There should be a General Networking topic area!

I have a small NT network that spans between two buildings via a coaxial backbone. One building is wired with Cat5 10bt, the other building has a bus system using the backbone to connect to four PC workstations, one LINUX box for my UUCP gateway, and 5 Amiga 2000 systems. All I want to do is take the PC's off the coax, drop a hub in the place of one of the PC's, and install 10BT cards/cabling. I want to leave everything else alone. The problem is that once everything is installed my 4 PC's (that are plugged into the hub) can only see each other and the rest of the network cannot see them.

I have made sure my cards work by plugging the PC's in from a different area, I swapped the hub with another hub to make sure it worked. I've tested the cables. Everything seems to be in order. Also, when the hub is plugged in, the other PC on the bus can still see the whole network as usual.

Can anyone help with this????
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Question by:honnonc
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Expert Comment

by:amarko
ID: 1561472
Honnonc
           Do you have the two ends of the cozx cable terminated properly?

Amarko
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Expert Comment

by:TimCaturaHouser
ID: 1561473
This sounds too familar!

The challange I faced in this was identical, except for nothing but PC's. The bottom line was the hub did not support 'cascading'. I changed to a new (now very inexpensive) hub, and life was good.
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Author Comment

by:honnonc
ID: 1561474
Hmmm, this has crossed my mind! I am using these inexpensive, 16-port BocaHub's but can't find anything regarding cascading in the literature. I have a 3com SuperStack II without the BNC port. Maybe I will purchase the BNC port and see how that goes.
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Expert Comment

by:TimCaturaHouser
ID: 1561475
My experience has been if they don't mention cascading, they don't do it. :-(
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Expert Comment

by:squint
ID: 1561476
How far apart are the buildings?  Have you exceeded the maximum recommended cable length?  

If so, the signals are just too weak to be split over the hub.  You can use a repeater, or you could just route with your Linux box.
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Author Comment

by:honnonc
ID: 1561477
Tim, you're probably right. These are cheap hubs!

As far as the distance between the buildings - this is an addition to an existing, working system. The workstations in the other building have been running on this bus system for two years. I would have to assume that the distance is fine for that reason. I have to admit that I think it is sketchy - the buildings are on opposite sides of the street, diagonally. But, like I said, it's been working! I am more inclined to agree with the cascading problem.

Oh, also - the hub is an active hub. It doesn't simply split the signal, it acts as a repeater. It would be interesting to play around with the LINUX box as a router though :-)
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Expert Comment

by:ycs
ID: 1561478
Just a thought, but if cable run length is not an issue, I would be inclined to look at trust relationships between domains - this is only a suggestion but if one domain does not trust another perhaps this could responsible.
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Expert Comment

by:TimCaturaHouser
ID: 1561479
great thought, if he had NT running.... I still believe the hub age is eating him..... This challange will show up in the aug issue of MCP mag, horror stories.... it is one paragraph of the ugliest time I have had in the '90's. Only one uglier was in the '80's.

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Expert Comment

by:paulnic
ID: 1561480
honnonc,

Does the Boca hub have any signal lights for the BNC port?  What do they show?

Also...would it be worth a test with the hub replacing JUST ONE of the coax-connected PC's, leaving three still on the bus?  I'm not sure what you're doing with the "loose ends" when disconnecting four from the coax....

Peace^^Paul
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Author Comment

by:honnonc
ID: 1561481
I DO have NT running, but it's a single domain. The BNC port LED does not show any activity - the Boca Hub doesn't use it for that purpose (<sarcasm> very helpful). The BNC and AUI LED's is only used to check LINK status.

I think the answer is probably that the Boca hub doesn't allow cascading via the BNC port. It DOES however allow me to use the 10bt port to cascade. I tried cascading the two haubs side by side on my panel and it still wouldn't work.

Tim - I bet I'm repeating your headache. I will look for that article in MCP magazine!
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Expert Comment

by:seychell
ID: 1561482
10base-10 and COAX do the same job, but at different frequencies.  You will nead a BNC port on your hub.  You can get a balast that is RJ45 at one end and BNC at the other. This will rextify your problem, fairly cheaply, bit these are hard to find, unless you know how to convert a transever to do the job.

So at the end of the day you probably better with a new HUB.  ACCTON have a HUB, it was $200.00 (Australian) - 8 port with one BNC. It will do the trick. So does D-Link.

Just to make sure before you go playing with cables - are you sure you can't ping anything on yor network ?
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Expert Comment

by:paulnic
ID: 1561483
honnonc,

1. When you tried cascading two hubs via 10BT, what if anything was connected to the BNC connectors?   Also, you know that a "crossover" switch, cables or port is needed to connect hub-hub or NIC-NIC in 10BT, yes?

2.  Have you tried putting the BNC hub in place of JUST ONE PC?  It's hard for me to imagine someone adding a BNC port to a 10BT hub that will not allow you to connect 10BT to a BNC backbone.  This seems to be what you want, and it's usually the main reason for the BNC or AUI port in the first place!  Which reminds me...is there a setting (maybe even inside, hope not!)  to switch between BNC and AUI?

3.  FYI, seychell, i'm not sure a balun or ballast will do what you want...10BaseT uses four conductors and requires active repeater circuitry on each port; coax uses two conductors and does not require repeaters.  Here in the states you can get an 8x10BT+BNC hub from Compex for, would you believe, $39.95 USD?
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Author Comment

by:honnonc
ID: 1561484
seychell: I have to reopen the question as it doesn't sound like you read all of the comments.

I can ping all of the workstations before I add the hub and I can ping the workstations NOT connected to the hub AFTER the hub is installed. The workstations I connect to the hub can only see each other (via Net. Nbrhd.) but aren't getting an IP assigned by my DHCP server. There is definitely NO exchange of data via the BNC port.

Also, I'd like to repeat that I attempted to cascade the hubs on my panel with just three feet of cable and with both ends terminated from the rest of the backbone; still got nothing. I am looking for more information regarding this particular hub and it's BNC cascading features.

Paulnic - Yes, I know about the X-switch; I don't have any problems connecting one hub to another via 10bt. I DID try connecting only one PC and terminated it from that point back. Also, each of the Boca Hub's work fine individually. I have tested three of them on the BNC backbone and they all work great, one at a time. For this reason I have to go back to the idea that they may not be cascadable via the BNC port or something. I think I have ruled out everything else.
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Expert Comment

by:adelator
ID: 1561485
Are you sure the bnc port is working on the new hub?  you can cable 1 ws to it via coax, and another to a 10bt port and see if they can "see" each other.  That way at least you'll know the coax port is working.


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Accepted Solution

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paulnic earned 100 total points
ID: 1561486
You say,

     For this reason I have to go back to the idea that they may not be cascadable via
     the BNC port or something. I think I have ruled out everything else.

From looking at the manual, with various multihub diagrams but NONE using the BNC between two hubs, I'd have to agree with you and Tim about the BOCA 16+.

What to do?  How about a look at http://www.cpx.com/mh8.htm

The Compex MicroHub 8 w/cascadable BNC (up to 30 hubs can cascade off coax backbone) is $39.95 plus shipping from DataComm Warehouse, 1-800-328-2261.  Lifetime warranty.  Unless the policy has changed recently, DataComm Warehouse will take it back in 30 days if you don't like it.

Besides handling your PCs directly, it'll give you 10BT to cascade to your Bocas.

Peace^^Paul

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