Cisco Support Community
Community Member

many-to-many dynamic NAT?

I (and many others, i think) have the following issue:

2 always-on ISP connections, for example Cable and ADSL, both with 1 public IP address. No routing protocol available with these ISP's. Both interfaces addresses have public addresses but can be on completely different subnets.

I would like to do some form of bandwidth teaming. Both ISP connections should be used to distribute outgoing TCP connections.

It seems to me this should be possible with a Dynamic NAT mechanism that uses 2 public interfaces, instead of multiplexing everything to 1 public interface.

I realize that it won't speed up large file transfers since these can only go over 1 interface. And there are other issues like browser http sessions that go partly out over one (translated) ip address and partly over the other public ip address, which might confuse web servers / firewalls etc.

It seems to me this is a 'hot item' since more and more private homes and companies (at least here in the Netherlands) have a choice of cable, adsl, always-on isdn and even 802.11b/g wireless connectivity to the Internet.

Community Member

Re: many-to-many dynamic NAT?

How may ‘inside’ IP addresses are you working with on your LAN? If you are doing this to service more than 1 or 2 systems on the LAN, you could simply use static routes to route some IP addresses to outside interface 1, and some IP addresses to outside interface 2.


Lance Wantland

Community Member

Re: many-to-many dynamic NAT?


Thanks for your reply. I already considered separate static routes (and am using my 2 ISP connections now as such). In my situation this is only for 1 or 2 systems. I would like some kind of dynamic load sharing or ISP connection teaming between the 2 public interfaces.

What i was thinking of is a nat overload setup that uses more than one outside interface, and a nat mapping mechanism that uses a round-robin mechanism to translate the internal tcp sessions to 2 (or more) outside addresses. I don't believe that can be done with current IOS, although i must say that i have yet to explore all nat/pat options.

CreatePlease to create content