In a Cisco 877 (IOS 12.4(15)T11) there are two Vlan interfaces:
Vlan1 (default vlan) with ip address 172.26.1.1 mask 255.255.0.0
Now I would like to add a Vlan10 with ip address 172.26.16.1 mask 255.255.255.0
i.e. the Vlan10 is actually a subnet of the larger Vlan1 space.
The router refuses this assignment, complaining that the addresses do overlap. Of course this is true. But is it a real problem? Systems on Vlan10 don't need to communicate with Vlan1, but both Vlans are routed to another site over separate IPsec tunnels.
Is there a global config command that would allow this setup?