passive hub , 66block whats the difference?

Discussion in 'Computing and Networks' started by Mathematics!, Apr 20, 2011.

  1. Mathematics!

    Thread Starter Senior Member

    Jul 21, 2008
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    Hi, I am wondering is it possible to create one of these devices just by
    using a 66block and punching all the cat6 wires down on it.

    I am also wondering if I did that what would happen would the computers beable to share the line's if I ran another line back to the router with all the computers connected together by the 66block?

    I am think the answer would be yes provided that you have some built in CDMA/CD software working on each computers NIC. Correct me if I am wrong though.
     
  2. mjhilger

    Member

    Feb 28, 2011
    119
    16
    What phys protocol? Strictly speaking the answer would be NO except for a very limited type of phys connection. I think you are trying to implement something similar to the old ethernet on coax. This has many problems, which is why it is not used anymore. The token ring protocol was capable of using a passive hub, but you need to be able to switch connections in and out. So even punching down on token ring would require all computers powered up and active to work properly. Good luck on finding a router using this protocol!

    There are other protocols that could share connections, but they would not be cost effective nor fast compared to 100M ethernet or 1G ethernet, so why go down this road? You would need the specific NIC and drivers to work in your computer to make any of these others work. Then, you might be limited as to the high level protocol (like TCP/IP) that is available (drivers/software) to work with that phys connection.
     
  3. Wendy

    Moderator

    Mar 24, 2008
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    I had an active Ethernet hub using coax. It fried, but it was similar in configuration to the 10BaseT versions (Cat 5) by 3M (I had examples of both). The main problem with 10Base2 (coax) is network cards would occasionally die in a mode nicknames "screaming", with the card being a "screamer". Basically it would start transmitting without listening, and disable that network line for any other cards on the network.

    Strictly speaking it was not a token ring, as it did not loop back in any form. Both ends haveto be terminated with a 50Ω load to prevent reflections, and this impedance was critical. You can disconnect the BNC T connector without bringing the network down (mine is still active) but what good does that do, it is the insertion of new coax that will kill the network for the duration.

    I'm slowly getting out of the mode, but my house still has 10Base2 used in it. Most old network hubs (I have several) have one BNC connector and 9 10BaseT, with the new stuff coax is a memory, which is why I still have several hubs in storage. Me and my brother were buying network cards before it was popular, or known, for a multihub BBS. That's why I still have ARCnet hardware (the precursor to Ethernet, only 2.5Meg/sec) in my garage, and it had passive hubs. However, I used active hubs for it too.

    Far I know there have never been passive hubs for Ethernet 10Base2, and I've looked. Impedance and signal levels are too finicky for that. I'm not sure, but I suspect 10BaseT (T is for twisted pair) has the same problems. As cheap as powered hubs and switchers (the new standard) are I wouldn't mess with it.

    My house network, active since 1983 or so, has working examples of 10Base2, 10BaseT, 100Mhz Ethernet (from the Verizon hub), and wireless. I'm no expert (that was my brother when he was alive), but I have a long history with them.
     
    Last edited: Apr 29, 2011
  4. BillO

    Well-Known Member

    Nov 24, 2008
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    I am assuming you are talking about 10 base T.

    In that case no. 10 base T has transmit and receive signals on different pairs. If you just parallel all the lines on a connection block you just end up with all the transmits together and all the receives together. No communication will take place because nothing will 'hear' what anything else is 'saying'.

    You can create a cross-over cable for a 2 node system, but that is the limit.

    10 base 2 does not require hubs within the specs for a single segment. It transmits and receives on the same circuit using carrier frequencies. Collisions are frequent and there are physical limits to the number of nodes on a segment. Typical throughput is about 30% of bandwidth. Segments must be connected via a hub, and the hubs must be active in order to match impedance between segments and to allow for proper timing, even if the segments are much shorter than the maximum length.

    Hubs, even switches cost less than an egg sandwich these days, so I have to beg the question, why do you want to avoid using one?
     
  5. BillO

    Well-Known Member

    Nov 24, 2008
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    Ethernet is not a token passing protocol. Packet collisions are allowed and are arbitrated (or not) by the layer 2 protocol.

    BTW, the ring in token ring (an IBM protocol) is logical, not necessarily physical, although I suppose that is also possible.
     
  6. mjhilger

    Member

    Feb 28, 2011
    119
    16
    BillO is 100%. Ethernet 10 base T or 10 Base 2 and Token Ring are different phys protocols. Token ring was an IBM thing during the PS/2 days originally in 4Meg then 16 Meg. Token ring hubs were passive but had relays internal that would switch the node in or out as power was supplied by that node - hence somewhat capable of being punched down with many constraints.
     
  7. Wendy

    Moderator

    Mar 24, 2008
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    I was disagreeing with the previous statement it was a token ring, if you read what was written.

    Old ethernet 10BaseT used 2 twisted pairs (4 wires). Old 10Base2 was a single coax line. I still have a lot of old hardware for it, such as Tees.
     
  8. BillO

    Well-Known Member

    Nov 24, 2008
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    I've got dozens of those BNC 'T's too. I use them as a kind of Leggo set and make weird things with them.
     
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