You can see a very limited static view of the Tx and Rx bytes for a fiven IPSec Lan-Lan tunnel in ASDM Monitoring. See the screenshot below (click on it for larger view).
The Netflow analysis tool ntop is free and runs on a Linux server (free OS) which you can even build on an existing PC using something like Virtualbox (also free) of you don't have an available Linux host.
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...