NAtive VLAN?what is the use of vlan?VLAN in trunk link?

[vasanth77]

what is the use of native VLAN in trunk links? where should i change native vlan from vlan1 to another?

what is the use of untagged native VLAN frame?

[Madhukrishnan Gopinathan Nair]

Hi Vasanth,

By defauly native vlan is 1 and if you wish to change it you have to change it under your trunk interface (both side link)

(config-if)#switchport trunk native vlan <vlan #>

Ideally we dont want any packets coming as untagged over a trunk interface and as a best practice you can configure the native vlan as an unused vlan on your switches.

Hope this helps and grade my post if it is useful.

Thanks,

Madhu.

[Guru Mysoruu]

HI Vasanth,

 802.1q defines packet tagging to differentiate between different Vlans

The one without Tagged are identified as native Vlan Traffic 

Hope you go it

Regards,

Gurudath K S

[Madhukrishnan Gopinathan Nair]

Vasanth,

Does this answer your questions. If you have further questions please feel free to ask, else i request you to mark this questions as answered.

Thanks,

Madhu

[vasanth77]

i got it,

you are saying that packet out of the trunk will be tagged,

but why should they  are implemented native VLAN as untagged?

if tagging all packets out of trunk port is good then native VLAN too?

my question is where would i take advantage of untagged traffic?

where untagged traffic is used?

[Madhukrishnan Gopinathan Nair]

Hi,

On ethernet, you can connect more than one device to a port. So when you configure a port as trunk, it expects a vlan tag to arrive. But some times there are devices which dont have the capability to tag the packet and still they need to connect to network. So they can use native vlan to have connectivity. It is not a usual situation, but it helps on some situation where multiple devices connected on a trunk and not all have ability to send tagged frames. Hope this helps.

Please do remember to rate all useful posts.

Thanks,

Madhu

[Madhukrishnan Gopinathan Nair]

Also you can refer to this posts for some more information.

https://supportforums.cisco.com/discussion/10811246/why-native-vlan-exists-trunk

Thanks,

Madhu.

[Madhukrishnan Gopinathan Nair]

Hi Vasanth,

Do you have any more questions?

Else i request you to rate posts and mark the question as answered.

Thanks,

Madhu.