Quick question out of the 10/8 are you using all of the 16 million addresses??. If not - you need to work out how many subnets you are using, you know how many they are using ... 1 /9 and 1/11 looks like the other company implemented a planned ip subnet design.
Then I think the easiest thing you should do is nat on a summary boundary.
Table of ContentsIntroductionVersion HistoryPossible Future
UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
Types used with Twice NAT / Manual NAT and Network Obje...
Table of Contents Introduction:This document describes details on how
NAT-T works. Background: ESP encrypts all critical information,
encapsulating the entire inner TCP/UDP datagram within an ESP header.
ESP is an IP protocol in the same sense that TCP an...