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Old 05-30-2007, 08:06 AM
Martijn Lievaart
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Default Re: Low Cost Hub With Read-Only Ports?

On Tue, 29 May 2007 19:11:45 +0000, Vernon Schryver wrote:

>>Guess it's all a red herring and a hub is HDX. Period.

>
> When writing for netnews, you can nod to the old, correct terms, but if
> you want to be understood by (or helpful to) most readers, you must use
> the words they encounter in the trade rags and stores and from their
> friends.


True, but can an 10/100 multiport bridge be FDX or is it always HDX? That
was my question. I still fail to see how it can be FDX except in very
specific circumstances (which may still make sense). (I do see how a 2
port bridge can be FDX).

Even if it is theoretically possible, are/were those really made?

(Note that this is not an entirely academic question, I do encounter
"hubs" on our network on an almost daily basis. These are always
connected to switchports that are set to 10/HDX on one end and devices
that are set to auto/auto on the other end. We never encountered any
problems, but I want to be prepared).

>
> If you try to byy an "Ethernet hub" at a retail store, you will probably
> leave with a device that automatically handles connections to hosts and
> at least one other "hub" and at mixture of 10 and 100 MHz. It might
> even lack a special "uplink" socket with the TX and RX pairs swapped but
> instead switch pairs on any socket automagically. Only if you shop at a
> used equipment dealer can you hope to find a real 10-BASE T hub.


I still have several, especially for sniffing (but I never tried a rx-
only cable). As I have several 10/100 bridges.

> We recognize "10/100 hubs" as multi-port bridges, but if you try to buy
> any sort of "bridge" at the retail store, you are likely to be
> disappointed.


Yes, these are generally not on sale anymore :-)

> If you try to buy an "Ethernet repeater," you might get some flavor of
> 802.11 device that acts like a 2 port Ethernet bridge and is neither
> what the radio people used to call "repeaters" nor what the IEEE 802.3
> standards called "repeaters."


Interesting. Yes, IIRC the original repeaters were plain amplifiers. IIRC
(again) thick and thin ethernet both could do a certain length (1,5Km?
900mtrs?) based on the RTT of the frame, but needed amplification to
achieve those lengths.

Nowadays one can buy ethernet 10base-whatever repeaters (I DON'T mean
802.11 repeaters, I work with those daily and if I never see another one
it's way too late). I guess those repeaters are really just 2 port
bridges/switches. Is this correct?

TIA,
M4

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