ISR 2921 interface trunking

[darren.g]

Folks.

I've got (unfortunately) a third party installing some new networking kit for me, and I can;t get the connection to work.

Basically, it's a 2921 connected to an ISP MPLS network on one port with a link into a switch on the other.

Because we wanted to plan in advance for the days of VoIP, we asked them to put in two VLAN's - one for data, one for voice. For now, we've only activated one of them.

The port config looks like this

interface GigabitEthernet0/1

no ip address

duplex auto

speed auto

!

interface GigabitEthernet0/1.10

description DATA VLAN

encapsulation dot1Q 10 native

ip address 10.50.70.254 255.255.255.0

My question to you leaned gents is - do they need the "native" statement on the end of the dot1q config line?

The switch connecting to the router is a cheap-arse netgear, but it *is* VLAN capable, and supposedly capable of dot1q - and I've configured it with a single VLAN on the port in trunk mode - but I can't get the workstations hanging off the switch to connect.

Does the "native" keyword mean the trunk passes ONLY untagged traffic (I.E. strips the VLAN tag from the traffic) which originates in VLAN 10 on the router, or does it mean that the port passes VLAN 10 traffic *and* untagged traffic?

Thanks for any input.

[Reza Sharifi · Accepted solution]

My question to you leaned gents is - do they need the "native" statement on the end of the dot1q config line?

They don't need the native keyword unless they want vlan 10 to be the native vlan (untagged) instead of vlan 1.

Does the "native" keyword mean the trunk passes ONLY untagged traffic (I.E. strips the VLAN tag from the traffic) which originates in VLAN 10 on the router, or does it mean that the port passes VLAN 10 traffic *and* untagged traffic?

Correct, with native keyword, the trunk only passes the untaaged vlan and not both tagged and untagged.

you can only have one statement under the interface

encapsulation dot1Q 10 native

or

encapsulation dot1Q 10

and not both. after adding the first one if you add the second one it will replace the first one and vise versa.

HTH

[darren.g]

Thanks Reza, that was what I needed to know.

Now I just have to fly 900k's to fix the stuff up. :-)