Port down when i force in speed 100 3

[crocodanser]

Hi,

I have a Cisco 3560. I must plug a XLAN link on a port. This port must be forced at 100Mb full duplex to enable the connexion.

When i forced the port, the interface become down...

Why?

If i let the config in auto negociation, the switch negociate a half duplex and i have missmatch duplex error.

Here, the configuration of this interface :

interface GigabitEthernet0/24
description Vers le XLAN
switchport trunk allowed vlan 60,63,65-68
speed 100
duplex full
!

here, the show version :

Cisco IOS Software, C3560 Software (C3560-IPSERVICES-M), Version 12.2(25)SEE3, RELEASE SOFTWARE (fc2)
Copyright (c) 1986-2007 by Cisco Systems, Inc.
Compiled Thu 22-Feb-07 14:40 by myl
Image text-base: 0x00003000, data-base: 0x0109B76C

ROM: Bootstrap program is C3560 boot loader
BOOTLDR: C3560 Boot Loader (C3560-HBOOT-M) Version 12.2(25r)SEE4, RELEASE SOFTWARE (fc1)

TR-3560-HDV-3-1 uptime is 53 minutes
System returned to ROM by power-on
System image file is "flash:c3560-ipservices-mz.122-25.SEE3/c3560-ipservices-mz.122-25.SEE3.bin"

cisco WS-C3560G-24PS (PowerPC405) processor (revision F0) with 118784K/12280K bytes of memory.
Processor board ID FOC1034Y24L
Last reset from power-on
7 Virtual Ethernet interfaces
28 Gigabit Ethernet interfaces
The password-recovery mechanism is enabled.


Thx a lot for your help.

Best regards,
Olivier Legras

 

[ADB100]

With the newer switches (2960, 3560, 3760) the hardware on the copper ports have Auto-MDIX capability - i.e. you don't need cross-over cables to connect two DCE devices together (I assume XLAN device is a DCE - i.e. you can connect a PC directly to it without a cross-over cable?). When you force the speed or duplex on an Auto-MDIX port it also disables the Auto-MDIX feature so you will have to use a cross-over cable.

I also noticed you are using this interface as a trunk but haven't hard-coded the trunking configuration. By default the interface will attempt to negotiate a trunk using the Cisco propeitary DTP protocol. If the neigboring device doesn't support this then a trunk won't be established. You should hard-code this if it is indeed to be used as a trunk:

switchport trunk encapsulation dot1q
switchport mode trunk
switchport nonegotiate

HTH

Anyd

 

[crocodanser]

thx a lot for your help. i will try this later.

Best regards,
Olivier Legras

 

[crocodanser]

i tried your answer but that does'nt work... My question was not clear.

The problem come from the duplex and the speed. The interface become down when i use this command :
speed 100
duplex full

And not when i type the trunk command. When i withdraw trunk commands, and i use speed 100 and duplex full, the interface stay down.

Have you got another idea?

Thx a lot

Best regards,
olivier Legras

 

[ADB100]

My comments regarding the trunk commands were a side issue; these will have no effect on the physical functioning of the interface. Ignore these comments if you are happy with the VLAN Trunk configuration.

I understand your issue is with hard-coding a 10/100/1000 Gigabit Ethernet Interface to 100Mbps Full Duplex. My original comments still stand though - What type of cable are you using between the two devices? I assume it is a straight cable.
Have you tried using an Ethernet cross-over cable between the two devices when you hard-code the Cisco end as 100Mbps/Full-Duplex? A standard Ethernet 10Mbps or 100Mbps UTP cross-over cable is wired:

1 - 3
2 - 5
3 - 1
5 - 2

The other pins do not need connecting.

Andy

 

[crocodanser]

i use cross over cable. And this cable works fine with my 3750 switch actual. I want to replace it by this 3560.

Thx a lot for your help,

Best regards,
Olivier legras

 

[crocodanser]

Another Idea?

 

[ADB100]

Another Idea?

Sorry no. You could try upgrading the IOS on the 3560 to a later release as that version is quite old now - latest is 12.2(46)SE. However I doubt this will help. I have never seen the behaviour you describe so I can only assume there is something weird with the XLAN (what ever it is?) or you are doing something wrong.

Andy

 

[crocodanser]

ok i'll try to upgrade ios.

Thx a lot

 

[vipergg]

I think it s a mdix issue also . It may work with your 3750 but that may be running mdix also . I don't think the IOS version has anything to do with it .

 

[ADB100]

Yeh, it sounds weird. Both the 3560 & 3750 default to Auto-MDIX being enabled - forcing the speed or duplex obviously disables this feature. The only thing that I am not too sure about is if there is any peculiar behaviour with the ports being 10/100/1000. He didn't mention if the 3750 it was to replace was 10/100.

Andy

 

[burtsbees]

Physically, what device is connected to gigabitethernet 0/24?
If it's another Cisco, can you show the config for it on that interface? Maybe a sh run on both devices to see anything extra?

Burt

 

[crocodanser]

Hi,

Ok i can answer now.

This problem came from cross over cable. I used cross over cable since the begining. I tried just one time with a straight cable but with the command speed 100 and the problem was always here.

Yesterday, i tried with a straight cable and just forced the duplex in full and not the speed.

And.... That's worked fine!!

So thx a lot! I Love you!! lol

Kind regards;

Olivier legras

 

[ADB100]

OK, so it was an Auto-MDIX issue as we originally thought. The XLAN is obviously a DTE device, however this was masked by the cross-over cable you used and Auto-MDIX correcting it for you. When you forced the speed & duplex the Auto-MDIX functionality was disabled and therefore it 'broke' the fix it was doing previously.

Glad you got it working in the end.

Andy