Absolutely, use PAT! PAT can handle much, much, much more than 250 users. What happens is, the pool is used in consecutive order. Which means, when PAT can no longer use the first address, it moves on to the second, and the third, and so on for the pool. If you only have 250 users, then they will always be using the first address, and you would be wasting the other addresses away, because they would never be used.
For example, I had 225 users on my network with a pool of 15 IP Addresses for NAT. If I were to have every one of those users hit a web page at the EXACT time, that web page would show the IP Address of that user being the first address. You would never roll over to the second.
When I learned of this, I removed my pool, and overloaded my interface with a single NAT entry. I still did not get any perfomance decrease.
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...
[toc:faq]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 and UDP are I...