Native Vlan

[rcasta]

Perhaps it's a nonsense question, though I'd like someone at this forum to explain (is if I were 4 =) ) what exactly is Native vlan !! (I think it's not the same as default vlan , isn't it?) ..what is it for ...if not defined then what?? and lastly, how to know what ID or which Vlan to assign as native vlan.

thank you in advance !

 

[marks66]

The Native VLAN on Cisco 5000/29xx etc switches is by default VLAN1. However if you use Dynamic Trunk Protocol to negotiate encapsulation etc the Native VLAN must match and be trunked to all switches within the same VTP Domain. For example if you do not trunk the default VLAN to all switches then you will have to make the Native vlan one that is.

Hope This answers you question.

Cheers

Mark

 

[krr]

Simply put, on a trunk all packets are tagged with their VLAN id except for the native VLAN which goes through untagged.

This is the reason why the native or untagged VLANs must match on both ends of a trunk. Both ends assume that untagged packets belong to the native VLAN.

Other vendors let you set VLANs as tagged, untagged or excluded on a port (and btw. they use the term trunk for something completely different, comparable e.g. to Cisco EtherChannel).

Cheers *Rob