Load Balancing problem with Cisco 1811

[stefv]

I use a Cisco 1811 to load balance two DSL lines on a LAN.
If I use the configuration described on Document 99427 (IOS NAT Load-Balancing for two ISP Connections) on cisco web site, it works fine if the two DSL line have IP address on different subnets (the IP adress are fixed).
But sometimes, we have sites with 2 DSL lines with IP address on the same subnet. And the 1811 does not allow to have IP from the same subnet on 2 different FastEthernet interfaces.
The only way that I found to make it work (but that is not an acceptable solution) is to use another router to NAT one of the IP to another subnet.
Is there a way to solve this problem without any additional equipement ?

 

[burtsbees]

Well, you could make it look like two different subnets, if the addresses are right---like subnet them into two /30 subnets, or you may be able to use /32, I am not sure. It may be worth a try...

What class are the IP addresses, and what is the last octet (don't need the first three)?

Burt

 

[stefv]

For some sites, I can use different subnets. But for some others, it's not possible (example x.y.z.42 and x.y.z.43).

Any other idea ?

 

[burtsbees]

Maybe true for a /30, but why not /32?
Shot in the dark here, I have never tried, but I don't see why it would need a nw address and broadcast address...

Burt

 

[dtrtel]

So you are connecting two DSL modem/routers to two Fastethernet interfaces on your 1811. So are the DSL modem/routers doing PPPoE/DHCP and passing a private address to the 1811 Fastethernets? Or are they in bridge mode so you do are doing PPPoE/DHCP at the 1811?

You will want your 1811 Fastethernet interfaces to be assigned the outside global (public IP) addresses from your ISPs.

It makes a big difference.


--jeff

http://linkedin.com/in/JeffLynch