Two 8 port 10Base-T hubs Linked to one 24 Port...

Ryan J Standish <r @acsu.buffalo.edu> writes:

Correct.  This is chaining hubs together.  It has two disadvantages over
using a proprietary stacking scheme (or just getting a bigger hub):

1: A packet that travels through both hubs gets delayed more
2: Packets that travel through both hubs go through two repeaters,
   instead of one.  The Ethernet spec has a limit to the number of
   repeaters you can have in a single LAN segment (4, I think).

If you use a straight (non-crossover) cable, you should connect one
normal port to one "uplink" port.

If neither hub has an "uplink" port, or if they're already in use, you
can use a crossover cable and connect two normal ports to each other.

-- David

OK.  Then I was mistaken about the repeater limit.  I thought it was
only 3.

My point is that connecting hubs via crossover cables (or straight
cables with a crossover port) is not really stacking.  It's just
chaining together more repeaters, which adds packet latency and moves
you closer to the repeaters-per-segment limit of the Ethernet spec.

Hubs that are attached with proprietary stacking ports act as one single
repeater, and usually transfer packets between the hubs faster as well.

-- David

that is correct, it is nothing more than  a crossed over port

Not really, you can stack upto 4 hubs per segment via this method, (using the
crossover that is)

Hope this helps

Khash Sajadi

Charlie,

That sounds nice and straight forward, BUT i have two hubs that i want to link
to the
BayStackHub and there is only ONE uplink port. Have you any ideas??

Emil Bjorsell

Sorry everyone my mistake, I understand NOW that i have to connect the cable into
the
up link port on the two 8 port hubs and then into any two regular ports on the
BayStackHub.

Thanks to everyone who replied to my question. I appreciate it greatly. ;-)

Best Regards,
Emil Bjorsell

Sure, plug in a cable from the uplink port on each of the 8-ports to a
regular port on the 24, and you're there.  Make sure the uplink port is
switched to uplink mode if it's switchable.

--

--John

Reply to jclarke at eye bee em dot net.

ROF,L.  BAY NETWORKS JUST WENT OUT OF BUSINESS?!?!?!??!.  More like they
just _bought_ half the network hardware manufacturers in the universe.

--

--John

Reply to jclarke at eye bee em dot net.

Are you sure this is as you describe?  The fact that you connect the
"link" port to a normal Ethernet port on the other hub tells me that the
link port is nothing more than a normal Ethernet port with the wires
crossed.  In other words, it's no different from using a crossover
cable, except that it lets you use the straight cables that are easier
to find in stores.

Using this technique, a computer on one hub, sending to a computer on
the other hub, is sending his signal through two repeaters.

When he was referring to "stacking" hubs, I assumed he meant something
like what 3Com, SMC, Intel and other vedors do.  They have proprietary
connectors on the hub (the 3Com LinkBuilder FMS on my desk has a pair of
50-pin micro-D connectors on it.  Other hubs have other kinds of
connectors).  Special cables (and sometimes terminators) are used to
connect several of these hubs (mine supports 4.  I've seen some that
support 8 or more) so that they all act as a single repeater.

Three 12-port hubs connected via proprietary stacking connectors will
behave as a single 36-port hub (meaning there's always one repeater hop
between any two ports).  These same hubs, connected via their Ethernet
connectors will not act in this fashion, and there may be as many as
three repeater hops between two ports.

Unfortunately, the original poster has not yet described what kind of
connector his "uplink" connectors are.

-- David

Emil,

In the days gone by, to connect 2 hubs together, we used to use a
cross-over cable. However, in the last year or 2, companies have
been providing the same functionality as a cross-ver cable via a
'cascade' or 'uplink' port on hubs.

To connect them properly, connect one end of you network cable to
a 'normal' on you BayNetworks hub, and then connect the other end
to a 'uplink' port on your compaq hub. Note that on some brands
of hubs that have 'uplink' ports, the 'uplink' port is used
INSTEAD of the port next to it. eg. If the port next to the
uplink port on the hub has wording or a diagram indicating some
sort of link, then you lose the functionality of the other port.

eg on my smc hub - Adjust to monospace font to see correctly

+---+---+---+---+---+---+---+-­--+---+
|   |   |   |   |   |   |   |   |   |
+---+---+---+---+---+---+---+-­--+---+
  1   2   3   4   5   6   7   8  link
                              +---+

Here I can have either 8 ports on one segment, or 7 ports (port 1
to 7) + a link to the next hub (via the 'link')

if your hub does not indicate any relationship between the
'uplink' port and any others, then you get the use of all of your
ports

Darren

Nope, Bay Networks is still going strong. Just check out NYSE for the
BAY symbol....

Charlie Clemmer
Bay Networks

I was wrong.  They're still in business, but they're going through some
kind of merger with Nortel.

Sorry for accidentally spreading misinformation.

-- David

Emil,

The uplink ports on the Compaq hubs should be electronically crossed
over so that you can use a typical straight through patch cable in order
to link two hubs together. This would be the same type of patch cable
you are using to connect PCs to the BayStack hub.

Nothing special needs to happen, just use regular patch cables to
connect the uplink ports on both Compaq hubs to regular ports on the
BayStack hub. Make certain that you are within the distance restrictions
for 10BaseT, but that's about it.

Charlie Clemmer
Bay Networks

In article <35CEEEE6.25802 @tinet.ie>,
  Emil Bjorsell <e @tinet.ie> wrote:
Emil,
Just connect the hubs from the uplink port back to any port on the Bay hub.
Most hubs have a port marked MDI/MDIX (Possible uplink??) which is either
autoswitching or has a small button to reverse polarity to enable the hubs to
communicate. A simple cross-over cable would also do the same thing. The
smaller hubs just appear as a extention of the large one.

--
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This should work.  
  The uplink ports should be fine if you connect them to the regular
ports of the main hub.  If not, try using a crossover cable on the two
hubs.

Connect the uplink ports of the 8 port hubs to regular ports of the 24 port
hub.

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In article <35CEEEE6.25802 @tinet.ie>,
  Emil Bjorsell <e @tinet.ie> wrote:

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This is not really an NT problem, so I doubt you'll get much help from
those newsgroups.  The fact that computers running NT are connected to
your network "hubs" doesn't change anything.

I would suggest contacting Bay, but I think they recently went out of
business.  I don't know about Topware.  You can probably get some useful
information out of Compaq.

I don't know any details about the devices you mentioned, but they have
fiber-optic connectors labeled "uplink", then this is probably not going
to be useful for stacking.  Boxes like that are probably Ethernet
switches, with the uplink port intended for connecting it to an ATM (or
some other kind of) switching network, for creation of virtual LANs
(VLANs) - meaning you won't be able to directly attach them together (at
least not using the uplink ports).  You'd have to attach each box's
uplink port to a network switch of the appropriate type, and then
configure VLANs using whatever method is appropriate for each box.

Of course, I could be wrong about this, since I'm just guessing.  If the
uplink ports are not fiber-optic, but multi-connector electical cable
connections (perhaps looking similar to micro-SCSI connectors), then
they are probably not ports for uplinking to a switching network.

They might be hubs (that is, repeaters) or Ethernet switches, or
bridges.  I've never heard of a hub/switch/bridge that can be stacked
with another vendor's device.

What you can do, if the hubs are truly hubs and not switches or bridges,
is connect the hubs via their Ethernet ports.  You can use a crossover
cable to connect an Ethernet port on one hub with the port on another
hub.  Just make sure you don't extend this chain to more than three
repeaters (or was it four?) or you'll end up violating the Ethernet spec
(maximum number of repeaters per Ethernet segment), and the network
won't work properly.

If these "hubs" are actually switches or bridges, then connecting them
via Ethernet probably won't work.  Many such devices have a hardware
limit to the total number of devices that can be attached to a single
Ethernet port (related to the ASICs learning source MAC addresses of the
attached device).  This limit is often very low - four or less, and the
switch/bridge will start behaving strangely if you exceed it limit.

You are really going to have to locate the documentation for your
devices and do some reading to find out what your options here really
are.

-- David