[c-nsp] Loopback/VLAN question

[Mikael Abrahamsson]

On Tue, 15 Dec 2009, Frank Bulk - iName.com wrote:

> Looks like I will be creating separate L3 domains.

If you can live with knowing what part of the IP pool belongs in what vlan 
then you can (this works with static addresses (no dhcp) anyway) route the 
individual parts of the unnumbered subnets to the vlan interface in 
question.

A static route to an interface means the ARP(s) will be done on that 
interface, so in conjunction with "local-proxy-arp" (which you seem to 
have missed in your conf?) you can do this:

int lo20
ip addr 192.168.1.1 255.255.255.0
int vlan10
ip unnumbered lo20
ip local-proxy-arp
int vlan20
ip unnumbered lo20
ip local-proxy-arp

ip route 192.168.1.0 255.255.255.128 vlan10
ip route 192.168.1.128 255.255.255.128 vlan10

Now you've split this subnet into two vlans and there is still full 
communication between them. How this interacts with dhcp, I don't know. 
You should try your original conf with added "ip local-proxy-arp" anyway.

-- 
Mikael Abrahamsson    email: swmike at swm.pp.se