Network Native

  Network address translation, or more commonly NAT, is most often used to do source NAT or destination NAT. In rare instances, SNAT or DNAT isn't enough to get ip packets to their destination. Enter twice nat. While twice NAT isn't a function I've needed often, it was a function drilled into me while studying for various Cisco exams. I used to watch Christian Matei explain it over at INE and it really helped me to understand what twice NAT is and how to configure it on Cisco devices. Previous to my time working with NSX-T, I'd only utilized twice NAT once. A few years back, a customer wanted to build and IPsec tunnel from the organization HQ to a branch office. The private ip space used by HQ and the branch used overlapping ip space. We used twice NAT to NAT the source and destination ip address in a single NAT rule ( similar to this guy ) before shoving it all into an IPsec tunnel. Previous to working with NSX, circumstances requiring twice NAT were uncommon.  While w...