Should a 568A to 568B Patch Panel run be changed?

Posted on 2010-08-15
Last Modified: 2013-11-09
I am the IT department for our small K-12 school.  I have done a lot of re-wiring over the last few summers and am pretty knowledgeable about wiring protocols and best practices.  I use the 568B standard exclusively, mainly because that was what was in place when I started.

The problem:  I had to add another cable to one of my top-layer patch panels last summer and discovered that both top-layer panels are wired to the 568A standard.   (I wired them.  I don't remember doing so and don't know what I was thinking, but I am the culprit.)  These two panels are absolutely the only 568A wired devices on the network.  I can't recall when I put them in, but it has been at least 3 years and I have not noticed anything that looks like a wiring-related performance issue.  

So my question is, "is this a problem?"   I have sort of an OCD need to fix it, but it will be a pain in the neck and I would just as soon not fix something that doesn't need fixing.  

My thought is that though everything still works, it might work better if I put everything on the same standard.  Is that correct thinking?
Question by:srsdtech

Expert Comment

ID: 33441262
The difference appears to be one of color on the wires only, so no functional difference:  
Comparing 568A and 568B
By looking at the first two specifications we see that the only difference is that the green and orange pairs are terminated to different pins, there is no difference as to what signal is used on what pin, only what colour wire is terminated onto it. So technically the standards are the same, they operate in the same manner and neither one is technically superior to another when used in Ethernet applications.

It is when an Ethernet system and a phone system are combined that the difference really becomes apparent.

Author Comment

ID: 33441413
So if you have a cable wired with the 568A standard on the main patch panel and terminated using the 568B standard in the wiring closet there should be no problem?

Expert Comment

ID: 33441591
If one end is 568A and the other is 568B, then you have a crossover cable. (They are very handy when you want to transfer data between two pc's without using a switch. I keep a red one in the car for just that.)  Many  switches can automatically detect crossover and compensate for it.  
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Author Comment

ID: 33441701
I know what a crossover cable is.  I also know about the pair switching on 568A and B.  If you read my post, I mentioned being pretty knowledgeable about wiring in general, which was my way of saying I already know all that information you can get from a 5-minute Google search.  But a 5-minute Google search does not shed light on my specific issue, which is why I am asking it in this forum.

Let me try to explain the situation differently.

What I have is a typical, small network with 4 servers, a main server room, 4 wiring closets, and about 175 drops.  Due to its location, the main server room also acts as a fifth wiring closet, with numerous close drops wired directly there.  Each closet has a couple switches and a couple patch panels.  An up-link runs from each switch in each closet to the main switch room, where it terminates on a patch panel, and then exits the network through my level one switch.  Every drop is run from a patch panel in one of the wiring closets to a Cat 5e keystone jack.  In this setup, we have patch panels, patch cables, and keystone jacks, all of which needed to be made or wired by me.  (I did purchase a few patch cables, but made most of them.)

Every one of these three types of devices (keystone jacks, patch cables, or patch panels)  is wired to the 568B standard WITH THE EXCEPTION OF the connections on two patch panels in the main server room.  The connections on the two patch panels are either remote up-links or local drops.  So what I have coming off those two patch panels is some connections that run from:
1.  switch to 568A patch panel  to 568B PP to switch
2.  switch to 568A PP to 568B keystone jack to Device

Everything still seems to work.  

My question:  is there any reason I should rewire the 2 switches to the 568B standard?

In other words, would I see a performance increase or would such a change be only for aesthetics?

Expert Comment

ID: 33442222
Sorry.  The short answer is that you get no benefit from rewiring.
LVL 27

Accepted Solution

Steve earned 500 total points
ID: 33442250
switches and many network devices automatically detect if they are on 568a or 568b wiring (this is often used as a way to detect switch>switch connections for example)

In many cases you wont notice if a panel is wired to the wrong standard, particularly if the patch panel in question is patched to itself or another device wired to the same standard.

If this panel is connected directly to something wired in the other standard then you may find problems.
This may occur if you patch one of the ports on a 568a panel to a port on a 568b panel, as this would connect the wrong wires together.

As you dont currently have a problem I assume most of the connections on the panel in this standard are either to network devices with autosensing or to items in the same panel.

Its good practice to maintain a single standard across your systems but it isnt a requirement and is unlikely to provide any particular improvements to your system.

Expert Comment

ID: 33442297

In example 2, it would seem that you are in fact reversing transmit and receive but auto MDI/MDIX is detecting the link and configuring it. Although no performance would be gained by rewiring, I would think that there is always the possibility that an older switch or system could be deployed and might not connect. In addition, I believe that in some cases if speed and duplex are hard set, auto MDI/MDIX will not function so I could see a config mistake causing a potential issue..

Just a thought..
LVL 79

Expert Comment

ID: 33453133
Changing what you have may not technically do much more than fulfill your OCD needs to be consistent, but consistency itself can be of value. What happens if you get hit by a bus and the poor schmuck that gets stuck in  your job can't figure out what is going on somewhere down the road?
On one hand - if it ain't broke, don't fix it.
On the other hand - it ain't broke now, but what about next guy?

Author Comment

ID: 33504264
Okay.  It sounds like there is not a lot to be gained by rewiring, other than some peace of mind and a feeling of thoroughness.  Both of which can be extremely satisfying.  I'll leave it for now, but will probably work in some way to fix it in the future.

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