2960x trunking issue on sfp ports

[n.bokhar1]

i have a 2960x that has this configurations ONLY i mean i haven't even added a host name

VTP mode off

spanning-tree mode rapid-pvst

spanning-tree vlan 1 root secondry

interface vlan 1

 ip add 10.1.1.2 255.255.255.0

----------------------------------------------------

and that is it

i also have a 3850 with this configuration:

vtp mode off

spanning-tree mode rapid-pvst

spanning-tree vlan 1 root primary

interface vlan 1

  ip adderss 10.1.1.1 255.255.255.0

interface gig 1/0/1

 sw mode trunk

----------------------------------------------

and thats it no more configuration

now when i connect my 3850 port 1 to ports 1-48 on my 2960x i have a fully functional trunking between them and i can ping but if i connect my 3850 to ports 49 and 50 on 2960 witch are sfp+ ports with cisco glc-t connected to them i cannot make trunking work and every thing fails and i dont know what the **bleep** is going on 

i have checked every thing

please help me i am pulling my hair right now

you also should know i have 7 other 2960x the same one that are working correctly but i have configured them all but this one had issues then and i couldn't fix it so i have erased my switch and now you know what is going on.

please help

[Reza Sharifi]

If the 2960x does not work with GLC-T, can you try connecting it to the 3850 using fiber?

HTH

[n.bokhar1]

1- i have 6 other 2960x the same model that are working with glc-t sfp modules

2- i have 6 other 2960x the same model that i have configured this way and are worknig correctly but this one even if i configure it wont work 

3- 2960 runs : 15.2(2)E6  and 3850 runs : 03.06.05E 

thank you all but i have tryed all of them and still i don't know why this is hapening on this switch if you want i can give you access to them 

[Derrick Hurley]

Have you tried the suggestions?  I understand that you have other switches that are configured the same and the configuration is working fine there.  What we're saying is the "auto" part might not be functioning right on this switch which could happen.  It's typically a best practice to hard code your trunk links as trunks to save some time and bring the links up faster without having to do DTP.

[Derrick Hurley]

You should hard code your trunk interfaces anyway instead of trying to rely on DTP. Add to your 2960X interface configuration:
switchport mode trunk

[Derrick Hurley]

You could also add the "switchport nonegotiate" command to the interfaces to disable DTP.

https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst2960x/software/15-0_2_EX/vlan/configuration_guide/b_vlan_152ex_2960-x_cg/b_vlan_152ex_2960-x_cg_chapter_0100.html#concept_F533C3ACF39C40A5A40469C9DB44984D

[Rich Uline]

Greetings,

Could you tell us what software versions you are running on the switches?

Also, DTP sometimes fails for a variety of reasons. Did you try setting the ports to trunk manually?

Swx3850(config)#int gig 1/0/1
Swx3850(config-if)#sw mode trunk
Swx3850(config-if)#sw trunk noneg
...
Swx2960(config)#int gig 1/0/49
Swx2960(config-if)#sw mode trunk
Swx2960(config-if)#sw trunk noneg

[Julio E. Moisa]

Hi

As it was mentioned previously, you can disable the negotiation or try with speed auto. 

[Georg Pauwen]

On a side note, I have looked around and it seems that there is a bug with certain IOS versions where the switch does not recognise the SFPs. When you do a 'show inventory' do you actually see them listed ?

Either way, the recommended fix is to downgrade the IOS to 15.0(2)EX3.

[n.bokhar1]

thank you guys but after manually configuring the trunk port nothing has changed and even a downgrade didn't help if any of you guys want I can give you all a remote access to both switches to check em out

[n.bokhar1]

thank you guys but after manually configuring the trunk port nothing has changed and even a downgrade didn't help

[n.bokhar1]

come on guys please help me I don't know what else to do

[Julio E. Moisa]

Hi

On the Switches 4948 you must specify the type of media, try to use this command on the 3850 or 2960x:

interface gx/x/x

metry-type <select the media>

or 

try the following

configuring auto the negotiation

conf t

default interface g1/1/1

interface g1/1/1

switchport mode trunk 

speed auto

duplex auto

no shutdown