Strange things...

[billmania]

I have an interesting question for the masses.

This is the setup. I ran new cables to some existing printers. I was replacing the current cable because it was visible in the basement. We are building offices and we need to get the cable above the drywall. The new cables were punched down into new jacks and into the patch panel. When i tested the cables they tested fine.

Here is the issuse. When I plug them into the 24 port switch they don't connect. I have switched from a straight thru or a crossover doesn't matter. Still nothing. I've switch to the cable that the existing printer is on and nothing. This is the part I don't understand, when I plug them into a 5 port Netgear switch and plug a cable into the 24 port switch they work. Why do I need the extra switch when the orginal one didn't? Would the wire punch downs effect this? Could it be the punch panel? I just don't know why this is so. Can anybody shed some light on this?


Bill

[Variable]

Assuming all your cables are good... I think the problem lies in you have a mix of cables with cat 5 or cat 6e and they are pinned differently. Again, based on my understanding of how you explained it, the problem is not resolved until there are two switches in the loop. Switches are generally intelligent; you are using two different wiring types to both devices and connecting the two devices together. The devices are correcting your mismatch by crossing the relevant pairs. Ethernet wiring is pretty simple. 568-b is the most common. Wire pairs for 568-b are OW O, GW BL,BLW G,BRW,BR The wires are used in pairs to receive and transmit. In the above example you are using 1 and 3 and 2 and 6. 568-a reverses them so you have GW G, OW BL, BLW O,BRW BR. Again only 1 and 3 and 2 and 6 are used. Switches will try and sense what is needed and if they can they will swap the wires.

Think of the packet, as it moves along from the printer to the switch, as a train on a trip to the country. It will simply follow the "path" you have created. In this case it is will take #1 train line to the number #3 terminal, as it passes through the city it goes over many rail switches. The train should stay on the #1 line all the way till it enters the terminal. If the train gets switched over to another line during the trip, it needs to get switched back before it hits the terminal or it will crash into the wall and everyone will be destroyed. When you take this trip on your existing railroad everyone dies. When you take two small trips, stopping at two terminals, everyone lives and gets to see grandma. It is failing because the train station managers (switches) realize you are on the wrong track and put you on the right track without you knowing, thus saving all the passengers from fiery dismemberment.

If you have a cable tester that shows the 4 wires used and you make a couple of little cables you can test if the pairs are switched. Both ends should be in 568-b (or “a” it doesn’t matter - just has to be consistent) so the lights should blink 1,2,3,4 on both sides; if they are switched you will see 1,3,2,4 on the other end.

If you do a google search on how to make 568-b cable you will find lots of color pictures to explain it. But obviously you have aptitude if you are doing this your self. You just need to follow one standard for straights and one for x over. Make your own cables - less headache when doing network jobs. I would use machine made cables for patch panel to switch. Just make sure they are the same standard as you use everywhere else.


V

[billmania]

I usually make my own cables and I normally make them 568-A. Would it matter what the jack is punched down to if it goes into a patch panel? So if the jack is 568-B then the cord from the patch panel going to the switch needs to be 568-B also. If this is true then why when I plugged it into the 24 port switch with a manufactured cord it was using before did it not work. When I change the punch down at the jack from A to B or B to A it didn't work?


Bill