We have a customer which currently have an ASA source NAT traffic going into a VPN tunnel to an IP different than the WAN IP. They are migrating to MX and I know that MX don't do SNAT, but I think the same end result can be achieved using the following:
On the MX I will create a flow preference which points the interesting traffic to the secondary WAN interface on the MX, this interface will be configured with the IP address that the ASA previously used as the source NAT address.
I'm also concerned how much of an performance impact this configuration will have on the MX device.
If anyone can confirm this to work it would be great.