[olug] victory and defeat w/Linux router @work

[Charles Bird]

ya I was afraid of RF being involved because I "swore" I 
checked the pinouts over and over. I guess I missed it and 
needed a night of sleep to finally notice. 
I thought it mighta been the amp for our uplink dish which 
is not too far away from the start of the 100M run, I mean 
the waveguide plumming is about 5 ft away. Not my doing or 
control. I was so sure that there was some sort of 6.5Ghz 
RFI going on, but nope. Its all good now. 
Theres some low-end Linux machines gonna be making their 
home there soon hopfully. I'm stoked. 
 
 
 
----- Original Message ----- 
From: "Daniel Linder" <dan at linder.org> 
To: "Omaha Linux User Group" <olug at olug.org> 
Subject: Re: [olug] victory and defeat w/Linux router @work 
Date: Thu, 14 Oct 2004 11:03:51 -0500 (CDT) 
 
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> <quote who="Charles Bird"> 
> > Yep, cant get signal from cross over or straight on the 
> > 100m leg 
>  
> When you say "signal" do you mean a link-light, a 
tone-generator, a 
> continuity tester, or something else? 
>  
> Neither the tone-generator nor continuity tester prove 
much on an ethernet 
> connection other than you have connectivity from 
pin-to-pin. 
>  
> I have seen a number of cases where the link-light test 
is just about as 
> worthless.  Most NICs just check for a voltage across 
certain pins -- in 
> most cases the NIC on the far end will bring up the 
DC-voltage enough to 
> turn on the remote sides link light, but once you start 
sending the 
> modulated signal across the wire then the RF component of 
the wiring comes 
> into play. 
>  
> Here is the testing methodology I would try.  If posible, 
can you bring 
> the complete cable back to your desk?  This will help 
eliminate a lot of 
> unknowns.  If so, then try options 1 and 2... 
> 1: Using either a continuity tester or checking the 
colors on the 
> individual wires, ensure that your wiring is correct.  
Since a lot of 
> cable manufacturers have gone to the muted coloring on 
the strands, I like 
> the continuity tester -- that ensures there is an 
eletronic connection 
> from pin-to-pin. 
>  
> 2: Once the pin-outs are verified, try plugging each end 
into known good 
> devices (PC and switch, or PC-to-PC if it is a crossover 
cable). 
>  
> If you are able to bring up a good connection with this, 
then you'll have 
> to put the cable back in place and continue 
troubleshooting. 
>  
> 3: With the cable in place, do a visual inspection of the 
cable route. 
>  = Does it pass over/under/near any flourescent or 
high-voltage lighting? 
>  = How about near any non-grounded electrical frames or 
machines? 
>  = Does it pass near power cords or high-voltage 
powerlines? 
>  = Near any other electronic equipment that might have a 
large transformer 
> inside it (photo copiers, laser printers, etc)? 
>  
> If all this checks out, you might have to 
purchase/beg/borrow/steal a 
> decent cable tester (Fluke, WireScope, etc) to do 
in-depth testing. 
>  
> At my previous job (network engineer at IPRevolution.net) 
we had a 
> WireScope testing tool.  It was really nice, but I 
believe it had a cost 
> of around $20,000 for the base system.  It had two smart 
ends that plugged 
> into the RJ45 and the auto-test feature would test all 
aspects of the 
> cabling and give a certification as to the level the 
cable works (10bT, 
> 100bT, 1000bT, Fiber, etc).  These high-end tools will do 
the indepth 
> testing you might need, but are quite costly if you don't 
do this on a 
> regular basis. 
>  
> If this it turns out that RF is causing the problem, or 
the run is going 
> through an electronically uncontrolled environment (i.e. 
outside, in a 
> manufacturing plant, etc) you might want to look at 
running a fiber 
> connection.  Purchasing a 100+ ft fiber jumper 
(~$150.00), and two 
> Fiber-to-100bT transceiver/media-converter (~$60.00) will 
be in the 
> $300-$350 ballpark, and the benefit is that the bump to 
Gig speeds would 
> just require a replacement of the trancievers. 
>  
> Good luck! 
>  
> Dan 
>  
> Found this tranciever on TigerDirect for $60.00: 
> 
http://biz.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=548196&CatId=203 
>  
> - - - - - 
> "I do not fear computer, 
> I fear the lack of them." 
>  -- Isaac Asimov 
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