And Bob, for your pressing for the answer, I'll honor you by taking out the trash tonight :)
On Thu, Mar 11, 2010 at 3:51 PM, Robert West <robert.w...@just-micro.com> wrote: > This is why I love this list. > > Lawrence, you are the "Dude of the day". > > In my home we shall honor you this evening as we dine and argue about my > uselessness. Useless yes, but now I posses knowledge that they do not and > that, my friend - thanks to you - will make all the difference. > > My hat is off to you. If I wore one, that is....... > > Bob- > > > > -----Original Message----- > From: wireless-boun...@wispa.org [mailto:wireless-boun...@wispa.org] On > Behalf Of Lawrence E. Bakst > Sent: Thursday, March 11, 2010 3:38 PM > To: WISPA General List > Subject: Re: [WISPA] Ethernet LEDs > > The link LED and all other LEDs for Ethernet Jacks/Connections are driven by > the Ethernet PHY chip or the Ethernet chip itself the PHY is integrated. > > Link is turned on by the PHY sensing the LIT (link integrity test) in > 10BaseT which I believe has become part of the auto-negotiation protocol in > later standards. This is part of the Layer-1 (Physical Later) protocol in > the spec. > http://en.wikipedia.org/wiki/Autonegotiation > > So to be clear it's not just a LED hooked up to one of the wire via a > resister or some analog hack like that. The PHY knows that their is another > PHY on the other side of the cable and if the PHY sees the other PHY it > turns on the LINK light. PHYs often provide other lines to show collision, > speed, and duplex and these can be tied into other individual LEDS or > bi-color LEDs. > > If the link lights are on at both ends the connection is good. It still > might be the case that a duplex mismatch or bad auto-speed negotiation could > cause problems. Both of these problems show up from time to time, especially > on older gear. For both cases the cure is often to fix the speed or duplex > on one side and that prevents the auto-negotiation from failing. > > One cause of not getting a link light is that a MDI/MDI-X mismatch. Most > newer chips have auto MDI/MDI-X which prevents the problem in most cases. > > leb > > At 12:52 PM -0500 3/11/10, Robert West wrote: >>Yeah, but which circuit? The transmit, receive or maybe the unused pairs? >> >>That got me wondering also. >> >>Anyone know what pair triggers the light??? >> >>Bob- >> >> >>-----Original Message----- >>From: wireless-boun...@wispa.org [mailto:wireless-boun...@wispa.org] On >>Behalf Of Justin Wilson >>Sent: Thursday, March 11, 2010 12:15 PM >>To: WISPA General List >>Subject: Re: [WISPA] Ethernet LEDs >> >>Simple terms it's the completion of a circuit. >> >>--- >>Justin Wilson <j...@mtin.net> >> >>On Mar 11, 2010, at 11:29 AM, Cameron Crum <cc...@dot11net.com> wrote: >> >>> This may be a little out there, but does anyone know what causes the >>> "link" light to show on an ethernet jack when the cable is plugged in? >>> Is it as simple as just attaching an led to one of the signal wires, >>> or >>> is there some logic in there. Just curious. >>> >>> >>> --- >>> --- >>> --- >>> --- >>> -------------------------------------------------------------------- >>> WISPA Wants You! 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