as far as I know the PIX does not provide any traffic shaping capability, but it supports QoS in the sense that it preserves the ToS field value of an IP packet while forwarding the packet to its destination.
This same feature is supported also when encryption is enabled (it is a standard IPSec feature which Cisco implements on every VPN-capable device/software, with the only exception of VPN software clients).
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...