[Tfug] Switch problem

[erich]

So far so good,

       I've rearranged the two switches, and they are powered up 24-7, and
no problems have showed up. Thus far only one of my machines registers
"full duplex" that is 2000Mbps. It's brand new. I have another machine
that's relatively new, and I'm wondering why that's not also full duplex.
I'm thinking that the intervening 50' cable might be de-rating it.

Erich

Bexley Hall wrote:
> Hi Louis,
>
> On 3/17/2013 12:37 PM, Louis Taber wrote:
>> I set up a test bed in my shop with 600 ft of Cat-5.  It
>> quite happily auto-negotiated to 100MBit/sec, but would move no data at
>
> OK.  So you came to this conclusion from empirical data.  I
> was hoping there was something I hadn't noticed in the written
> specification that would have clued you in on this scenario... :<
>
>> all.  Put an old hub at one end to force it to 10MBit/sec and it worked
>> fine.  See: 
>> http://en.wikipedia.org/wiki/Autonegotiation#Electrical_signals
>
> OK, so in each case, you get a "go" for the "Link" (LED) but the
> first case just leaves you with no *legitimate* signal at the far
> end.
>
> So, in Erich's case, the machine can think the link "up" and just
> never see any "in band" data (e.g., DHCP traffic)  (?)
>
> In which case, forcing the interface to a specific configuration
> (my original suggestion) should work?  I.e., don't *let* the switch
> "think" the link (end to end) is capable of anything that it *isn't*!
>
> [Though he stated that the slower/older NIC's seemed to be manifesting
> the most problems...  :-/ ]
>
>> A side note: I have contended for years that the SOHO market needed to
>> handle miss-wired cables and mid-x to reduce returns and customer 
>> service
>> costs.
>
> I think AutoMDIX adds another set of issues.  E.g., I suspect that was
> the problem I was having with my two Gb switches (separated by 8 ft
> of cable).  Powering them up *singly* would work but if they both
> came up together, they just sat staring at each other...
>
> But I agree with your observation.  A wise manufacturer would design
> in a way that would discourage the user from even *suspecting* the
> kit (assuming it most usually is NOT the culprit!).  Or, at the very
> least, provide a reassuring means by which the user can convince
> himself that the kit *is* or is *not* the (part of) problem!
>
>> Fiber will always be wonderful in the right environment.  2 miles off 
>> the
>> paved road 15 miles from Ukiah is not the place for a 1200 foot 
>> link.  The
>> fiber is not usually the problem.  It is the connectors on the ends 
>> of the
>> fibers.  If you have a fusion splicer, it is not a problem.
>
> I can recall watching the glass ends being meticulously polished for
> individual cables.  Woe be unto he who cuts said cable "accidentally"!
>
>> Oh, then there
>> is the cost of the NICs.  The original plan was to get rid of a second
>> satellite link costing about $100 a month.  Low data rates anyway.  They
>> currently are using a long haul Wi-Fi connection down to Ukiah.  The
>> 10Base-T connection has been in place about ten years now.
>
> I have several fibre interfaces that I have set aside for a run
> out to the back yard (looking for the extra isolation that they
> afford)
>
>> So far as "pushing-my-luck"  --  from Wikipedia:  (
>> http://en.wikipedia.org/wiki/10BASE-T#Cabling)
>
> Yeah, but 100 (or 150... or 200) meters of cable IN A BUILDING
> is different from a geographical span of that same distance!
>
>> Note there is no specific distance in the 10Base-T specification 
>> (150m is
>> about 500ft).  The location, being will off the grid&  on the ocean 
>> side of
>> the ridge, also provided a very low noise environment.
>
> I'd be more worried about its exposure to lightning strikes
> (not *direct* but, rather, *induced*) over such a long distance.
> The galvanic isolation afforded by the coupling transformers
> would be no match for an induced voltage spike from such a strike
> (No idea how far into the machine any potential damage would
> propagate).  I've lost (wired) phones from nearby strikes (the
> surge takes out the protection diodes across the line) -- and
> you *know* the phone company designs with this sort of thing
> in mind!
>
> But, I'm typically overly pessimistic about these things.  I
> don't like *fixing* things if I can figure out a way to prevent
> them from *breaking*, instead!
>
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