I have a Cisco 1801 VPN router (using PPPoA) which I currently have one PC attached to the Fe0 port which in turn picks up a DHCP address from the local pool within the router.
I am now planning to add a few more PC?s to the site and I was looking to use the extra 8 switchports available on the router.
Up until now I have been using a 2950 switch and hanging it off the Fe0 port so that I can also extend the subnet.
When I try to plug a PC into the extra switchports no DHCP address is obtained. From what I can tell I will have to create a VLAN on the router to assign the switchports too. However when I do this I am unable to extend the subnet from the Fe0 port onto the switch module as I receive a ?Subnet already in use? message from the CLI.
The reason you are seeing the error is because you are trying to use the same subnet for the fe0 interface and the vlan interface.
Usually the switch ports are used to connect hosts together and the fe0 port is for WAN connectivity. Therefore, I recommend you use the 8 ports on the switch for your hosts, by removing the ip address off the fe0 and placing it on the vlan interface. You could also place the 2950 onto one of those switch ports as well.
However, if you really need that extra port you can configure a bridged virtual interface and assign it to the vlan and the fe0 port. However, I do not recommend doing this as i've had a few problems in the past with customers trying to do this.
Let me know if you still want to do the BVI thing, otherwise try to stick with switchports for all hosts.
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...