Load sharing using BGP

[kjanakiraman]

I have Cisco 3640 which is multihomed with two isp's using bgp. I have one fast ethernet interface which is connected to cisco pix and behind which is my internal lan. I have configured the pix outside as x.x.x.x which is the ip provided by isp 1 and all the webservers and internal systems are NAted and PATed using the network x.x.x.x. Now what i want to achieve is when the the isp 1 load is more than 50% the load should be shared to the isp 2 which has provided me with the network y.y.y.y. Is this possible?

Can anyone advice me in this.

Thanks in Advance

[thisisshanky]

It would be much better, to utilize both the ISPs at the same time, since you are paying for the service for both. You can do this by NATing your local address to ip address from both pools, x.x.x.x and y.y.y.y. on the pix firewall. You can add multiple nat commands to perform this.

You can configure load balancing to the same destination (in the internet) using the command "maximum-paths 2" command.

[kjanakiraman]

Thanks a lot for your reply. But the Cisco Pix does not have routing capabalities so i could do nat for a different isp since i can have only one outside and global configuration in the cisco pix.

Thanks in Advance

[thisisshanky]

You can split your local address using two nat/global commands.!

nat (inside) 1 10.1.1.0 255.255.255.128 ( 126 hosts will be nated)

nat (inside) 2 10.1.1.128 255.255.255.128 (next 126 hosts willl be nated)

global(outside) 1 x.x.x.x

global (outside) 2 y.y.y.y

This might of help

[kjanakiraman]

Thanks a lot. One more lost question. Is it ok if i have one outside statement that points to x.x.x.x like

nat (outside) x.x.x.x1

global(outside)1 x.x.x.x2

global(outside) 2 y.y.y.y2

Will the gloabl outside will make sure it send the packets designated to it to the other isp?

Thanks in Advance