Unable to hard code the ports of cisco 3750x series switch

[EZRA SHYAM]

hello,

I have tried with hardcode to 1000 7 Full on the ports which are connected to another switch.

After changing the port to auto from one side of the switch port came up. Is there any solution to make port up when both sides are hard coded to 1000 & full duplex.

Simple Words:

Switch 1 --> Switch 2 --> Hard coded to 1000 & Full --> Down.

Switch 1 --> Switch 2 --> Auto on one end to Switch 1  --> Up.

Switch model:

Switch 1 Cisco 3750x (Gi Switch)

Switch 2 Cisco 3750 (Gi Switch)

Regards,

Ezra.

[Leo Laohoo]

After changing the port to auto from one side of the switch port came up. Is there any solution to make port up when both sides are hard coded to 1000 & full duplex.

Let me guess ... the cable you are using is a straight-through cable? 

If this is the case, then hardcoding the ports to 1 Gbps and full duplex will disable MDI/MDI-X.  This will cause your ports to go down.

Besides, why do you want to  hardcode the speed and duplex settings between two Cisco switches?

[EZRA SHYAM]

yes correct.. I'm using striaght cable.

as per our standard we need to hardcode the ports.

How to resolve the issue using with stright cable? Is it possible without cross cable?

[cmarva]

Ezra,

as per the 1000baseT (IEEE 802.3ab) standard, it is an autonegotiate media. I have seen some ports locked at 1000 and mostly have problems although I have seen a few that have worked. But I generally have not seen gig ports locked, and generally have had bad experiences when they are locked. Particular to 1000baseT ports, locking speed and duplex probably isn't the best approach. Leo makes a good point also about the MDI feature.

just my opinion - chris

[Joseph W. Doherty]

Disclaimer

The  Author of this posting offers the information contained within this  posting without consideration and with the reader's understanding that  there's no implied or expressed suitability or fitness for any purpose.  Information provided is for informational purposes only and should not  be construed as rendering professional advice of any kind. Usage of this  posting's information is solely at reader's own risk.

Liability Disclaimer

In  no event shall Author be liable for any damages whatsoever (including,  without limitation, damages for loss of use, data or profit) arising out  of the use or inability to use the posting's information even if Author  has been advised of the possibility of such damage.

Posting

Yes, it's possible without a straight through cable, enable auto/auto both sides.    Otherwise you'll need a cross-over cable.

BTW, if your standard is hard coding copper gig ports, for speed and duplex, you might consider bringing your standard up to date.  Copper gig standard went much further in how auto/auto is supposed to work.  By disabling auto/auto, I believe, you're also disabling some error monitoring too.  Generally, all the major players, e.g. Cisco, would recommend auto/auto for copper gig Ethernet.

[Leo Laohoo]

as per our standard we need to hardcode the ports.

What standard are you talking about?  CURRENT standards or "best practice" recommends auto/auto. 

How to resolve the issue using with stright cable? Is it possible without cross cable?

Not possible.  If you want to hard code speed and/or duplex you also disable MDI/MDI-X feature.  If you want to hard code speed and/or duplex then you must use cross-over cable.  You can't have it both ways.  This is the main reason why I've stated the so-called "standards" your network is using is an OLD standard which pre-dates MDI/MDI-X features. 

[EZRA SHYAM]

Why auto/auto is best practice? can you please explain more on this?

If i disabled MDI/MDI-X feature on the switch, wht will be the disadvantages?

[Leo Laohoo]

If i disabled MDI/MDI-X feature on the switch, wht will be the disadvantages?

You would be NUTS if you disable MDI/MDI-X.  I am not saying this in jest.   Read what is MDI/MDI-X and tell me if you would still consider disabling this feature.

Why auto/auto is best practice? can you please explain more on this?

Let me turn this question around.  What is the benefit of hard coding speed and duplex? 

[EZRA SHYAM]

There will be no negotation traffic if we hardcode the ports.

[Leo Laohoo]

There will be no negotation traffic if we hardcode the ports.

Not precisely.  If you hardcode speed and duplex, obviously, when you connect a client to your switch and router, speed is set and duplex is set.  However, like I said before, this is OLD SCHOOL.  Do this now between two appliances and you'll also see the "ugly" side in forms of line erros, like CRC line errors.   In the "wild", if you hard code speed and duplex settings, you have to also MAKE SURE that the client is the same as your settings.  What happens if you hard code a port for speed 1000 and someone replaces this client with something else and will not talk speed 1000 but speed 100? 

And then you disable MDI/MDI-X.  Let me ask you this:  How many cross-over cables do you have in your office?  I have >900 switches in my network.  You want to know how many cross-over cables I have in our office?  I will tell you the answer:  ZERO. 

Whoever has made a decision to hard code speed and duplex settings need to go out of his comfy office and look around. 

[Leo Laohoo]

Rule of thumb when it comes to speed and duplex:  Leave both to "auto" and set only in extreme conditions.

[Leo Laohoo]

If i disabled MDI/MDI-X feature on the switch, wht will be the disadvantages?

If MDI/MDI-X is bad then how come every wired NIC nowadays support MDI/MDI-X?  From switches, routers, PC's, printers, servers ... ALL OF THEM.