That is by design. The only instance when CAM will know that your PC is not on the network anymore (if it's behind an IP phone) is when a new MAC address is noted on the port. For this to work you have to use MAC-NOTIFICATION, and not the LINKUP-LINKDOWN traps on the CAM
In the upcoming 4.8 release you'll have an option of notifying the CAM when you logoff the machine, but that is not out yet.
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...