Access ports an Native Vlans

[gservicios]

Hello,

we have a router with access port on native vlan and a switch with access port on vlan250, the switch native vlan is still vlan 1.

Now my doubt is if the switch permits only vlan250, how is it possible that the traffic is flowing to and from the switch and the router? it is because native vlan trafic is untagged?

Here is the config:

Switch:

int gi1/0/25

switchport acces vlan250

switchport mode acces

on Router:

int gi0

no ip address

Regards

[Joseph W. Doherty]

". . . how is it possible that the traffic is flowing to and from the switch and the router?"

Because the switch port isn't defined as a trunk port.  As an access port, all its traffic is untagged.  (Ditto for your router port, which, BTW, doesn't use VLANs, but can use tagged frames if such assigned to subinterfaced, which, in your posting, it does not.)

"it is because native vlan trafic is untagged?"

We use the term "native VLAN" for a (Cisco) trunk port VLAN's frames that are untagged.  Again, your posted switch port is configured as an access port.

[MHM Cisco World]

same as PC connect to SW, 
PC send untag frame 
if this frame need to forward via trunk 
the SW check the VLAN assign to this port and add tag to frame and forward it via trunk.