The ASA doesn't support load-balancing or policy-based routing, so no you can't load-balance between two ISP unless you know the destination of the traffic you want to send across the second link. For example, you can send VPN traffic across one ISP and non-vpn traffic across another because we know the destination of the traffic, but you can't send http traffic through one link and non-http traffic through the other.
With two ISPs you can do high-availability and have ISP failover. Here is a link to that.
Re: ASA FIREWALL CONFIGURE TO HAVE TWO ISP INTERNET ACCESS?
As we are implementing two isp, one isp is main and the second is the back up. Our condition is to utilize also the second isp link, Multiple context mode is helpful but it iseems that we cannot change our setup for the firewall which is single mode. Is it possible say that the main isp link will utilize 65% of the traffic and the remaining traffic will be handled by the second isp?
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...