Two questions regarding NATIVE VLAN

[qiblatain1400]

Dear All,

I have configured VLAN2 as a Native Vlan by "switchport trunk native vlan 2" command.

I used the command "sh int trunk" to check the Native Vlan status. But I got the Vlan1 as a Native Vlan, not the Vlan 2.

Then I made a FastEthernet port on which I assigned the Vlan 2, as a trunk port by command "switchport mode trunk", I got the Vlan 2 as a Native Vlan by "sh int trunk" command.After making the FastEthernet port as a trunk, I was unable to ping another host in the same Vlan 2.

So, Now I have two questions regarding my scenario :

1) What is the exact command in order to verify the Native Vlan (In order to check, which VLAN is configured as a Native Vlan) ?

2) Is it required to have a trunk port in order to configure the Native Vlan other than VLAN 1 ? (e.g if 5 interfaces on Switch 1 are in Vlan 2 & we have to make Vlan 2 as a Native Vlan, Is it necessary to make these 5 interfaces trunk, on which Vlan 2 is assigned) ?

[Haris P]

1) What is the exact command in order to verify the Native Vlan (In order to check, which VLAN is configured as a Native Vlan) ?

show inerface trunk

2) Is it required to have a trunk port in order to configure the Native Vlan other than VLAN 1 ? (e.g if 5 interfaces on Switch 1 are in Vlan 2 & we have to make Vlan 2 as a Native Vlan, Is it necessary to make these 5 interfaces trunk, on which Vlan 2 is assigned) ?

Only you have to define the native vlan on trunk interface . Basically if a switch receives untagged frames on a trunkport, they are assumed to be part of the vlan that are designated on the switchport as the native vlan .

So if you have a trunk link between Sw1 and SW2 ....and if you put native vlan 2 ,then whatever devices connecting on the hub will be on VLAN 2 and this will hosts will be able to communicate with the VLAN2 hosts in SW1 and SW2

SW1.......hub......SW2

interface FastEthernet0/7
switchport trunk native vlan 2

Regards

haris

[qiblatain1400]

Dear Haris,

About my second (2) question, I am not able to get your point of view.

I have two switches, which are connected to each other by fastethernet 0/1 interfaces. Both interfaces on both the Switches are configured as a trunk.

Now I have fastethernet 0/2 on both Switches which are connected to the Hosts in the same subnet & have been assigned Vlan 2. Now I have configured this Vlan 2 on both Switches as a Native Vlan by "switchport trunk native vlan 2". But when I type "show int trunk", I get the Native Vlan as Vlan 1, not the Vlan 2.

I think you got my point.

So please if you clarify more..........

[cadet alain]

Hi,

Could you post output of : sh int x/x trunk, sh int x/x switchport, sh run int x/x, sh vlan br

Regards.

Alain.

[Haris P · Accepted solution]

Dear Naveed ,

What you need is the below config on both switches

interface FastEthernet0/1

description connected to other switch F0/1

switchport mode trunk

interface FastEthernet0/2

description connected to PC VLAN 2

switchport access vlan 2

switchport mode access

Now to have communication between this two PC's no need to change the native vlan on F0/1 .By default the trunk will carry all VLAN traffic.

The trunks carry only tagged frames and all untagged frames will go to native vlan 1 .

Also in some old switches you may need to put switchport trunk encapsulation dot1q on trunk interface .Also if the above config not working try adding "switchport trunk allowed vlan all "

Now if you configure like , your native vlan will be vlan 2 . and it should be same in both switches f0/1 . and in that case if you put show interface trunk it should show as native vlan 2

interface FastEthernet0/1

description connected to other switch F0/1

switchport trunk native vlan 2

switchport mode trunk

sh interfaces trunk

Port        Mode         Encapsulation  Status        Native vlan
Fa0/7       on           802.1q         trunking      10

[qiblatain1400]

Dear Haris,

I did configuration according to your post, It worked fine.

We have to configure the native vlan on the trunk interfaces of the Switches, which are connected to each other.

Thanks for you all for your support.