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Community Member

trunk port disables all vlans in switch

Dear Sir,

i'm working with 2 cisco 3750 G series switches.testing bed is as follows:-

1) 2 different VLANs are working in both switch.

2) Trunk port is enabled.

3)2 vlans are working fine in each switch and communicating to each other well.

4) When i connect trunk port through a crossover cable,all ports of one swtch( which configured as vtp client)go DOWN and it never UP.

Again i have to reset switch and configure.

I have two questions:-

1) Why all ports go down when i connect crossover cable in trunk ports in both switches.

2) Is it necessary to configure one switch as a vtp client and one as a server.

a)If i will use both switches as vtp server, then what happened?

b)If i will not configured vtp domain SAME in both switches, then what happened.

Regards,

Siddhartha

3 ACCEPTED SOLUTIONS

Accepted Solutions
Hall of Fame Super Gold

Re: trunk port disables all vlans in switch

Hi Siddhartha,

What should i have to do if i will configure "vtp server" on both switches?

There are a significant few of us who will caution you with this. I have witnessed the danger and damaged when a long list of VLANs were deleted because a new switch, configured as VTP Mode Server, was attached to the network. Use this method with extreme caution and prejudice.

Community Member

Re: trunk port disables all vlans in switch

Hi~ siddindia

I prepared a simple example that I didn't test below lap.

However, I believe that it will be up and run.

※ Additional configuration.

1. Etherchannel configuration.

- Because of 2 lines(1/0/23-24)

※ Deleted configuration.

1. Routing configuration.

- If you have only just this lab, it isn't necessary to communicate the data between the SW1 and the SW2.

switch-1

================================================

switch(config)#vlan 100

switch(config-vlan)#name account

!

switch(config)#vlan 200

switch(config-vlan)#name hrd

!

switch(config)#int vlan 100

switch(config-if)# ip add 155.4.6.100 255.255.255.0

switch(config-if)#no shut

!

switch(config)#int vlan 200

switch(config-if)# ip add 155.8.6.100 255.255.255.0

switch(config-if)#no shut

!

switch(config)#int vlan 1

switch(config-if)# ip add 170.100.100.1 255.255.255.0

switch(config-if)#no shut

!

switch(config)#int range gigabitethernet 1/0/1 - 12

switch(config -if-range)#switchport mode access

switch(config -if-range)#switchport access vlan 100

switch(config -if-range)#no shut

!

switch(config)#int range gigabitethernet 1/0/13 - 21

switch(config -if-range)#switchport mode access

switch(config -if-range)#switchport access vlan 200

switch(config -if-range)#no shut

!

switch(config)#int range gigabitethernet 1/0/23 - 24

switch(config -if-range)#switchport

switch(config -if-range)#channel-protocol pagp

switch(config -if-range)#channel-group 1 mode desirable

switch(config -if-range)#switchport mode trunk

switch(config -if-range)#switchport trunk encapsulation isl

switch(config -if-range)#no shut

!

switch(config)#vtp domain bel

switch(config)#vtp mode transparent

Switch-2

========================================================================

switch(config)#vlan 300

switch(config-vlan)#name mkt

!

switch(config)#vlan 400

switch(config-vlan)#name business

!

switch(config)#int vlan 300

switch(config-if)# ip add 155.5.6.100 255.255.255.0

switch(config-if)#no shut

!

switch(config)#int vlan 400

switch(config-if)# ip add 155.4.8.100 255.255.255.0

switch(config-if)#no shut

!

switch(config)#int vlan 1

switch(config-if)# ip add 170.100.100.2 255.255.255.0

switch(config-if)#no shut

!

switch(config)#int range gigabitethernet 1/0/1 - 12

switch(config -if-range)#switchport mode access

switch(config -if-range)#switchport access vlan 300

switch(config -if-range)#no shut

!

switch(config)#int range gigabitethernet 1/0/13 - 21

switch(config -if-range)#switchport mode access

switch(config -if-range)#switchport access vlan 400

switch(config -if-range)#no shut

!

switch(config)#int range gigabitethernet 1/0/23 - 24

switch(config -if-range)#switchport

switch(config -if-range)#channel-protocol pagp

switch(config -if-range)#channel-group 1 mode desirable

switch(config -if-range)#switchport mode trunk

switch(config -if-range)#switchport trunk encapsulation isl

switch(config -if-range)#no shut

!

switch(config)#vtp domain bel

switch(config)#vtp mode transparent

Community Member

Re: trunk port disables all vlans in switch

Good morning! Siddhartha

In my configuration scenario, I'm clearly sure that all VLANs will be communicated with each other without a dynamic routing.

If you want to use the dynamic routing,

Trunk configurations don't need anymore.

However several another configuration need in the SW1 and SW2.

Have a good day!

Regards,

Kwangwon

16 REPLIES
Hall of Fame Super Gold

Re: trunk port disables all vlans in switch

Switch 2 ...

You have VTP Mode CLIENT but you are creating VLAN 300 and VLAN 400. You can't "create" a VLAN when you are in this mode.

Please rate when applicable and/or helpful.

Hope this helps.

Community Member

Re: trunk port disables all vlans in switch

ok.

Then what i have to do? when i have to implement two vlans in each switch.

Regards,

Siddhartha

Community Member

Re: trunk port disables all vlans in switch

You need to do the following:

switch(config)#ip routing

switch(config)#vtp domain bel

switch(config)#vtp mode server

switch(config)#vtp password 1234

However before making the change make sure the VTP revision is higher than your other switch otherwise your other switch will overwrite your vlan's with one's that it is aware of. Additionally I would add the other vlan's on the other switch to this switch before connecting the two switches together.

If your other switch is configured as a VTP server. Then don't make the change I mentioned above. Instead add the vlan (vlan 400) to the other switch prior to connecting the switches together.

Please rate.

Dan

Community Member

Re: trunk port disables all vlans in switch

Thank Dan for your esteemed response.

But i'm really confused,in which switch what need to change for vlan communication in my senario(two different vlans in each switch). I need right help step by step.Please do needfull.Kindly answer my questions also in my previous post.

Regards,

Siddhartha

Community Member

Re: trunk port disables all vlans in switch

Can you run the command "show vtp status" on each switch and paste output here.

Community Member

Re: trunk port disables all vlans in switch

Sorry DAN,

i can not. setup is some other location, where problem is rising.

But i'm sure that i have not use-

"router(config)#version 2"

in vtp domain command.

Can i recover this problem with only use "router(config)#version 2" with vtp domain command in a switch?

Why all ports of other switch which is in this time configured as vtp client, goes down, when i connect trunk ports through crossover cable.

Regards,

Siddhartha

Hall of Fame Super Gold

Re: trunk port disables all vlans in switch

In VTP Server, you can create, save, delete VLANs.

In VTP Client, the switch can't create or save any new VLAN changes.

So in your situation, may I recommend you create, delete and make VLAN changes to Switch 1, which is running on VTP Mode Server?

Thanks.

Community Member

Re: trunk port disables all vlans in switch

ok..

It means, i have to create VLANs 100,200,300 and 400 in switch1(which is configured in "vtp server" mode) and applied on gigethernet ports which i want to take in VLANs 300 and 400.But, there is any requirement in to change in "dynamic routing" in any switch.

What should i have to do if i will configure "vtp server" on both switches?

One mmore confusion in my mind that why all ports go down in this condition(configuration is given in first posting.).

Regards,

Siddhartha

Hall of Fame Super Gold

Re: trunk port disables all vlans in switch

Hi Siddhartha,

What should i have to do if i will configure "vtp server" on both switches?

There are a significant few of us who will caution you with this. I have witnessed the danger and damaged when a long list of VLANs were deleted because a new switch, configured as VTP Mode Server, was attached to the network. Use this method with extreme caution and prejudice.

Hall of Fame Super Gold

Re: trunk port disables all vlans in switch

Hi Siddhartha,

I am happy to see we have solved your issues and thanks for the rating.

Hall of Fame Super Gold

Re: trunk port disables all vlans in switch

Whoopsie! Wrong post! :P

Community Member

Re: trunk port disables all vlans in switch

switch-1

switch(config)#int range gigabitethernet 1/0/23 - 24

switch(config -if-range)#switchport mode trunk

switch(config -if-range)#switchport trunk encapsulation dot1q

switch(config -if-range)#no shut

Switch-2

switch(config)#int range gigabitethernet 1/0/23 - 24

switch(config -if-range)#switchport mode trunk

switch(config -if-range)#switchport trunk encapsulation isl

switch(config -if-range)#no shut

!

Hi~ siddindia

First thing ,

Do you happend to know that the trunk have 2 protocols which are ISL and IEEE 802.1Q.

I think that you should configure the same protocol like "dot1q / dot1q" or "isl / isl"

I hope to solve your problem.

Regards,

Kwang won

Community Member

Re: trunk port disables all vlans in switch

Hi Kwang won,

encapsulation is differ in both swithces by mistake.You are absolutly right that same encryption should be in both side of switches.

What are thinking about my testing scenario:-

Two L3 switches with two different VLANs on each switch.Can you send me proper configuration specially VLANs and VTP at each switch?

You can take my configurations in my first post.

Regards,

Siddhartha

Community Member

Re: trunk port disables all vlans in switch

Hi~ siddindia

I prepared a simple example that I didn't test below lap.

However, I believe that it will be up and run.

※ Additional configuration.

1. Etherchannel configuration.

- Because of 2 lines(1/0/23-24)

※ Deleted configuration.

1. Routing configuration.

- If you have only just this lab, it isn't necessary to communicate the data between the SW1 and the SW2.

switch-1

================================================

switch(config)#vlan 100

switch(config-vlan)#name account

!

switch(config)#vlan 200

switch(config-vlan)#name hrd

!

switch(config)#int vlan 100

switch(config-if)# ip add 155.4.6.100 255.255.255.0

switch(config-if)#no shut

!

switch(config)#int vlan 200

switch(config-if)# ip add 155.8.6.100 255.255.255.0

switch(config-if)#no shut

!

switch(config)#int vlan 1

switch(config-if)# ip add 170.100.100.1 255.255.255.0

switch(config-if)#no shut

!

switch(config)#int range gigabitethernet 1/0/1 - 12

switch(config -if-range)#switchport mode access

switch(config -if-range)#switchport access vlan 100

switch(config -if-range)#no shut

!

switch(config)#int range gigabitethernet 1/0/13 - 21

switch(config -if-range)#switchport mode access

switch(config -if-range)#switchport access vlan 200

switch(config -if-range)#no shut

!

switch(config)#int range gigabitethernet 1/0/23 - 24

switch(config -if-range)#switchport

switch(config -if-range)#channel-protocol pagp

switch(config -if-range)#channel-group 1 mode desirable

switch(config -if-range)#switchport mode trunk

switch(config -if-range)#switchport trunk encapsulation isl

switch(config -if-range)#no shut

!

switch(config)#vtp domain bel

switch(config)#vtp mode transparent

Switch-2

========================================================================

switch(config)#vlan 300

switch(config-vlan)#name mkt

!

switch(config)#vlan 400

switch(config-vlan)#name business

!

switch(config)#int vlan 300

switch(config-if)# ip add 155.5.6.100 255.255.255.0

switch(config-if)#no shut

!

switch(config)#int vlan 400

switch(config-if)# ip add 155.4.8.100 255.255.255.0

switch(config-if)#no shut

!

switch(config)#int vlan 1

switch(config-if)# ip add 170.100.100.2 255.255.255.0

switch(config-if)#no shut

!

switch(config)#int range gigabitethernet 1/0/1 - 12

switch(config -if-range)#switchport mode access

switch(config -if-range)#switchport access vlan 300

switch(config -if-range)#no shut

!

switch(config)#int range gigabitethernet 1/0/13 - 21

switch(config -if-range)#switchport mode access

switch(config -if-range)#switchport access vlan 400

switch(config -if-range)#no shut

!

switch(config)#int range gigabitethernet 1/0/23 - 24

switch(config -if-range)#switchport

switch(config -if-range)#channel-protocol pagp

switch(config -if-range)#channel-group 1 mode desirable

switch(config -if-range)#switchport mode trunk

switch(config -if-range)#switchport trunk encapsulation isl

switch(config -if-range)#no shut

!

switch(config)#vtp domain bel

switch(config)#vtp mode transparent

Community Member

Re: trunk port disables all vlans in switch

Dear friend,

Thank you so much for your excellent response.

Actaully in my scenario, all VLANs musht be communicated with each other,Thats why i was using dynamic routing.

In your configuration, Is it possible that all VLANs will communcate with other.If Not, what should i do for that in your configuration?

In your configuration scenario, what will actually happen between VLANs?

REgards,

Siddhartha

Community Member

Re: trunk port disables all vlans in switch

Good morning! Siddhartha

In my configuration scenario, I'm clearly sure that all VLANs will be communicated with each other without a dynamic routing.

If you want to use the dynamic routing,

Trunk configurations don't need anymore.

However several another configuration need in the SW1 and SW2.

Have a good day!

Regards,

Kwangwon

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