Etherchannel design will work with interface pair as well ,provided the design is appropriate to take care of the asymmetry.
Coming to your design, if i understand the requirement correctly, you wish to create etherchannel between 3750 stacked switch and the pair of CAT6K. Enabling VSS on the pair of CAT6K switches and then creating etherchannel should help.But the flow symmetry will not be guaranteed ( meaning the same IPS may not see the forward and the reverse packets of the flow).
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...