Conference netcad::hub_mgnt

    As far as I know, all our UTP/STP repeater products have "crossover"
    connectors on the front panel ports.  This is to allow the use of the
    more common straight through cables when connecting the front panel
    ports to stations.
    
    I can't speak for the bridge folks.
    
    							Marc

I have a draft version of the 10BaseT IEEE standard. In section
14.5.2 of my Draft 10 copy, it states the following.

"A crossover function shall be implemented in every twisted-pair-link.
The crossover function connects the transmitter of one MAU to the
receiver of the MAU at the other end of the twisted-pair-link.
Crossover functions may be implemented internally to a MAU or elsewhere
in the twisted-pair-link............etc.
When a twisted-pair-link connects a DTE to a Repeater, it is recommended
that the crossover be implemented in the MAU local to the Repeater.
.....etc.
Implicit implementation of the crossover function within a twisted-pair
cable, or at a wiring panel, while not expressly forbidden, is beyond
the scope of this standard."

I didn't include the entire section on the crossover function, just the
parts I thought relevant to the question.
Like Mark said, Repeaters have internal crossover (Repeaters will usually
be connected directly to end nodes). Likewise, the DECswitch 900TX is a 
workgroup bridge, and as such also has an internal crossover on its 6 UTP
ports, as it too is intended to be connected directly to an end node via
a commonly available straight through cable.
The DECswitch 900EF and EE are not considered work group bridges, and as
such its UTP ports were decreed by our Architect folks to not have internal
crossover on their UTP ports. Instead it is assumed that the UTP ports on
these bridges (oops switches), will connect directly to a MAU with internal
crossover. I hope this helps answer the question on crossover function.

Bob

    Thanks Marc & Bob for the info. It was just that one of our
    competitiors had told the cust that we did not conform the IEEE UTP
    standard regarding 'crossovers', which I found hard to believe -
    obviously they were talking crap.
    
    Thanks again much appreciated
    
    Rich.

    We ran into a LOT of flack at RPS because of this.  Basically it got an
    engineer called out and he spent a few hours troubleshooting it.  Over
    the past two months I've been called about 4 times because of it.
    
    We may conform to the standards but it really MUST be called out in
    BOLD print print in release notes or flier with the product to avoid
    panic calls from customers.  (Panic calls = people from Digital = $$$)
    
    Could we get the documentation updated to reflect, call this out.
    
    Also a reference to the standard is always good.
    
    Regards,
    j
    ^--who is copying Bob B's note for  the customer who really griped
    about it and...(won't repeat what THEY said....)

    Jon, I agree - we should document the crossover requirements well. 
    
    But I don't think that will always be sufficient - people often read the
    documentation as a last resort. The people who deal with installations
    and troubleshooting will have to be aware that when there's an X on the
    port, you use straight through cabling, and if there's no X next to the
    port, you use a crossover cable.

    Every one of the TP repeater installation and configuration manuals for 
    the new generation repeaters, from the DETMM, DETTM, DETMI on through the 
    DETPJ, has quite a good treatment of this subject.  Every manual also has 
    a postage-paid return card for suggestions on how to make the manuals 
    better.  So we're meeting the spec, and we're documenting what cables
    are required for various situations.
    
    							    Marc
    	           TP Repeater Installation and Configuration Manual Reviewer

    	The installation manuals for the DECswitches and the PEswitch also
    have detailed discussions about cabling. There are illustrations
    showing the cabling requirements from the switch to either type of node
    (internal crossover or straight-through). The switches are marked with
    an "X" at the connector if there is an embedded crossover. The only
    switch with an embedded crossover is the PEswitch 900TX. The DECswitch
    900 EE and EF are both straight-through connections.
    	In reference to .5, you have to know what type of connector is on
    the other node to determine the correct cable type rather than just
    noting the "X" or not. The basic rule is that three must be an odd
    number of crossovers in the path. It doesn't matter how this is
    achieved.

    
    	 Re .-1
    
    	"The basic rule is that three must be an odd number"
    
    			Good slip or is that pun?:-)
    
    						Bill

There must be a postulate documented in some old math book which can support
this statement.  :-)

Albert Einstein

    >We may conform to the standards but it really MUST be called out in
    >BOLD print print in release notes or flier with the product to avoid
    >panic calls from customers.  (Panic calls = people from Digital = $$$)
    
    Golly, (for lack of better or stronger words), I don't know how much
    CLEARER we can get on the above. On page 2 of the AA-Q2E8C-TE release
    notes for the DECswitch 900EF Firmware Version V1.4.0 approximately 
    7�" down from the top of the page (or 2�" up from the bottom), is a large
    BOLD FACED title with a 5 line paragraph underneath it as follows.....
    
    [as copied from the AA-Q2E8C-TE release note except I can't re-create
    the same words per line]
    
    -[start of text]
    10Base T Ports  (this is in large font bold type)
    
    The DECswitch 900EF 10Base T ports are straight-through wired station 
    ports. To connect a straight-through port to a crossover port (for
    example, a repeater port), use a straight-through cable. To connect a
    straight-through port to another straight-through port (for example, a
    station), use a crossover cable. See the DECswitch 900EF Installation
    manual for more information.
    
    [end of text from release note]
    
    >Could we get the documentation updated to reflect, call this out.
    
    As shown above, it's in there (like in the Ragu spaghetti ad)
    
    >Also a reference to the standard is always good.
    
    There is no mention or reference to IEEE standards in the release
    notes, and there isn't any list of the applicable IEEE document
    numbers in the installation guide itself. There is a short sentence
    starting about 4�" down on page 1 of the Introduction chapter
    which states the following.
    
    "The DECswitch 900EF standards-compliant technology (IEEE 802.1d,
    802.1h, 802.1i, 802.2, 802.3, and ANSI FDDI) ensures operability
    in multivendor networks."
    
    Alas, we are all guilty of not reading our owners manuals for our
    new cars, VCRs, TVs, stereos, microwave ovens, PCs etc. So...I guess
    it shouldn't surprise me that our customers *aren't* going to read
    our release notes or our installation guides.
    Far be it for me to say anything further on this... %-)
    
    Bob.....sigh

    RE: .8 and .9
    
    Ok, so I am not an expert typist. At least it proves I got your
    attention and that you read every word. :)
    
    Thanks,
    	Mike

    
    
    BTW, there is a company in New Jersey that sells UTP crossover
    adapters. It is a potted device with an RJ45 UTP male connector on
    one side, and a RJ45 UTP female connector on the other side, with
    a built-in crossover. One could look like a hero when walking into
    a customers installation, and being able to pull � dozen of these
    out of your briefcase to bail out a customer who has a handfull of
    "mission critical" UTP links that need to be up and running ASAP.
    The company name and address are as follows....
    
    Computer Crafts Inc.
    57 Thomas Road
    PO Box 644
    Hawthorne, NJ. 07507-0644
    (Tel) 201-423-0405
    (Fax) 201-423-1648
    
    Part number on the bag is CCI/3008090-01
    I don't have a cost in front of me, but I'll guess it's maybe about a
    $.90-$1.75 item. I've place a call into a local mfg's rep to get a
    ballpark price, and I'll post it when I get a call-back.
    
    Bob