how to distribute traffic between ADSL lines

[n.sebastian]

We have a senario, A router with one FE and 4 ADSL WIC connected to the internet. Each ADSL gets ip address Dynamically form the same ISP. Can I load balance outgoing traffic to the internet with this 4 ADSL connection?. The FE port of the router is connected to a firewall, hence the outgoing traffic comes from a single source.

Can someone help me.

[pkhatri]

Hi,

You certainly can do so. As long as you have four routes (each of them equal cost) pointing out each of these interfaces, then CEF will load-balance over these interfaces automatically, on a per-destination basis. It does not matter that all your traffic is coming from the same FE interface.

If you are using default routes, you can use something like the following:

ip cef

ip route 0.0.0.0 0.0.0.0 atm0.32

ip route 0.0.0.0 0.0.0.0 atm1.32

ip route 0.0.0.0 0.0.0.0 atm2.32

ip route 0.0.0.0 0.0.0.0 atm3.32

Hope that helps - pls rate the post if it does.

Paresh

[n.sebastian]

Hi Pkhatri

How can NAT be handled?

[pkhatri]

Use a config such as the following (you will need to add IPs etc)

int FastEthernet0

ip nat inside

!

interface atm0.32

ip nat outside

!

interface atm1.32

ip nat outside

!

interface atm2.32

ip nat outside

!

interface atm3.32

ip nat outside

!

ip nat inside source route-map NATMAP1 interface atm0.32 overload

ip nat inside source route-map NATMAP2 interface atm1.32 overload

ip nat inside source route-map NATMAP3 interface atm2.32 overload

ip nat inside source route-map NATMAP4 interface atm3.32 overload

!

ip cef

ip route 0.0.0.0 0.0.0.0 atm0.32

ip route 0.0.0.0 0.0.0.0 atm1.32

ip route 0.0.0.0 0.0.0.0 atm2.32

ip route 0.0.0.0 0.0.0.0 atm3.32

!

route-map NATMAP1 permit 10

match interface atm0.32

!

route-map NATMAP2 permit 10

match interface atm1.32

!

route-map NATMAP3 permit 10

match interface atm2.32

!

route-map NATMAP4 permit 10

match interface atm3.32

!

Using the above config, each packet's source address will be NATed based on which interface it is switched out of, in a dynamic fashion.

Hope that helps - pls rate the post if it does.

Paresh

[n.sebastian]

Thanks