I've a limited public IP address so I need to use PAT which all the internal LAN users able to access out to the internet.I would like to know is there any limit how many internal IP can be translated thru the single public IP and will cause slow down compare to NAT.
Theoretically you could have 2^16 connections on one ip, but since people may have multiple connections outbound concurrently, you probably could have 1 to 10k users behind a PAT and have it work. It really depends on the number of connections though - if you had 10k users who don't send much email (thus generating conns as your mail servers send out) or surf the web, you could be fine. But if you have 1k users, and host a heavily trafficked website, you could possible have problems.
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...