Switch Port Trunk

Answered Question

Hello All,

I having a interface which is configured right now as

interface gigabitethernet x/x/x

swicthport acess vlan xx

swicthport mode  acess

spanning - tree portfast

And I want it to change to the following

interface gigabitethernet x/x/x

swicthport trunk encapsulation dot1q

swicthport  trunk native vlan xx ( same vlan number as above )

swicthport mode  trunk

speed 1000

duplex full

spanning - tree portfast

  • Commands to make the changes
  • Is there anyway to copy the configuration from a interface which is running a similar  

Thanks in advance

Soofi,

Correct Answer by Leo Laohoo about 6 years 8 months ago

Try the following method:

default interface Gig a/b/c

interface Gig a/b/c

copy-n-paste the commands.

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Correct Answer
Leo Laohoo Tue, 06/01/2010 - 15:42

Try the following method:

default interface Gig a/b/c

interface Gig a/b/c

copy-n-paste the commands.

Leo Laohoo Tue, 06/01/2010 - 15:58

Copy and paste which commands ?

These:

swicthport trunk encapsulation dot1q

swicthport  trunk native vlan xx ( same vlan number as above )

swicthport mode  trunk

speed 1000

duplex full

spanning - tree portfast

Thanks seems like it worked. however I got this error message is it some thing critical ?

%Warning: portfast should only be enabled on ports connected to a single
host. Connecting hubs, concentrators, switches, bridges, etc... to this
interface  when portfast is enabled, can cause temporary bridging loops.
Use with CAUTION

%Portfast has been configured on GigabitEthernetx/x/x but will only
have effect when the interface is in a non-trunking mode.

Reza Sharifi Tue, 06/01/2010 - 16:36

Hi

Since this is trunk port you need to turn off portfast

no spanning - tree portfast

HTH

Reza

Hi Reza.

Thanks for the reply... It is connected to hpyer v terminal and it is Dell who has recomended the port fast.. Even thoug  it is not recomemended by Cisco.

I have another issue ...

Even Thought the above mentioned port is been trunkated for some reason  I am still unable to talk to other VLAN that includes the default  VLAN on the swicth.

-> Command to check as to which VLANs are allowed on a certain PORT

->  How to add a specific VLAN on certain PORTS.

-> Or any better suggestion are welcomed

Thanks,

Soofi

Reza Sharifi Wed, 06/02/2010 - 15:50

[email protected]

Hi Reza.

Thanks for the reply... It is connected to hpyer v terminal and it is Dell who has recomended the port fast.. Even thoug  it is not recomemended by Cisco.

I have another issue ...

Even Thought the above mentioned port is been trunkated for some reason  I am still unable to talk to other VLAN that includes the default  VLAN on the swicth.

-> Command to check as to which VLANs are allowed on a certain PORT

->  How to add a specific VLAN on certain PORTS.

-> Or any better suggestion are welcomed

Thanks,

Soofi

Hi Soofi,

Do a "show vlan" or "sh spanning-tree vlan x" to see the ports in a specific vlan.

You don't add vlans to ports.  You add physical ports to vlans.

You should not run portfast if you are connecting to another switch.  Portfast is for end user PCs, printer,etc,....

HTH

Reza

Even Thought the above mentioned port is been trunkated for some reason  I am still unable to talk to other VLAN that includes the default  VLAN on the swicth.

-> Command to check as to which VLANs are allowed on a certain PORT

->  How to add a specific VLAN on certain PORTS.

-> Or any better suggestion are welcomed

Thanks,

Soofi

Leo Laohoo Wed, 06/02/2010 - 17:02

Command to check as to which VLANs are allowed on a certain PORT

show vlan [brief] will show you which ports are assigned to which VLANs.

show interface trunk will show you which ports are configured as trunk and what VLANs are allowed on the trunk (among the outputs).

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