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Can't ping vlan 1

Hi I have a Cisco 1801 router connected to layer 2 switch on fa0 using the interface as a dot1q encapsulation trunk.

On both devices I have setup vlans 30 and 40 and the communication works fine between them.  The respective subnets of either vlan can be reached on switch and router and my laptop when plugged into respective vlan interfaces on the switch or router.

But...

The native vlan 1, which I've given the IP of 172.16.17.1/28 on the Cisco and 172.16.17.2/28 on the switch, is not reachable on either device when pinging from the console of either.

For vlan 30, I set up the sub interface as:

int fa0.30

encap dot1q 30

I set up vlan 40 the same but with relevant changes.

Would need to specify int fa0.1 also?

Any help appreciated.

1 Accepted Solution

Accepted Solutions

paulstone80
Level 3
Level 3

Hi,

Have you specified the native vlan on the trunk interface on the switch?

Can you post the sh run interface xxx for the switch uplink to the router?

You also need to specify a sub interface on the router using encapsulation dot1q 1 native. Assign the IP address for vlan 1 to this sub interface.

HTH

Paul

Sent from Cisco Technical Support Android App

HTH Paul ****Please rate useful posts****

View solution in original post

4 Replies 4

paulstone80
Level 3
Level 3

Hi,

Have you specified the native vlan on the trunk interface on the switch?

Can you post the sh run interface xxx for the switch uplink to the router?

You also need to specify a sub interface on the router using encapsulation dot1q 1 native. Assign the IP address for vlan 1 to this sub interface.

HTH

Paul

Sent from Cisco Technical Support Android App

HTH Paul ****Please rate useful posts****

I read the response from Paul to say that it is required to configure a subinterface to have the router process vlan 1 as the native vlan. I do not agree with this. If the physical interface is configured with an IP address then that interface will process frames that do not have a vlan tag.

I would agree that configuring a subinterface for the native vlan is a good practice. But I do not believe that it is a requirement.

I agree that we need to see how the interfaces are configured on both devices. I think it would also be beneficial to see the output of show cdp neighbor detail from the router and switch. And the output of show interface trunk from the switch might be helpful.

HTH

Rick

HTH

Rick

get_rthym
Level 1
Level 1

Can you please post "sh int vlan 1" and sh vlan

Lake

Sent from Cisco Technical Support iPhone App

Thanks for the responses everyone.

My initial thoughts were correct. Paul Stone also got it.

I had to specify

int fa0.1

encap dot1q 1 native


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