[c-nsp] Load balancing via 2 ISP + NAT

[Sorin CONSTANTINESCU]

Hi,

I have an implementation for a customer which peers with 2 different
ISPs. The customer doesn't have an AS number and uses for the LAN
addresses from one of the provides. When traffic goes through the
interface of the second ISP, the source address is NATed.
                                   -----ISP1
(10.0.0.1/30)---------------------------
                                 /
LAN -- (nat inside) Router
(10.0.2.1/24)               \
                                   -------ISP2 (10.0.1.1/30)(nat outside) ------

There are 2 BGP feeds receiving ~1500 prefixes and a default route via ISP2.

The problem i'm facing is that when i receive a packet for the LAN
(10.0.2.10) from an IP address reachable via ISP2, the packet is
rewrited by NAT with the source address 10.0.1.1 (ISP2), this breaking
the connections initiated from outside.

I know the setup is really weired, but we had to find something
suitable for load balancing over 2 ISP without PI address and public
AS.

Do you know how i can avoid this problem?

TIA
-- 
Sorin CONSTANTINESCU
consta at gmail.com
Linux Registered User #222086