As far as I know a host from one vlan where its L3 interface resides in the firewall cannot ping the default gateway of another vlan on the same firewall like you would in a non-firewall router .. this is the way it is on pix/asa and would expect the same behaviour-restriction in FWSM..
If I am mistaken on fwsm perhaps someone could correct.
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...