vpn - ipsec usually takes something like 50 odd bytes of extra header and so you might want to reduce mtu so that it is fragmented in the first try and ensure correct packet delivery and reoder instead of retransmission due to fragmentation on the way, this way it helps in improving speed
also sometimes there are servers on which the mtu is hard set to something like 1300 or 1200 and in those cases we usually play around with mtu
but having said that, i have not seen many playing around with mtu unless there is an issue
if you want you can change mtu to 1400 which should be safe for most applications
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...