I do not think that attempting load balancing using PIX firewalls connected to different parts of your network will work. With PIX deployed, the path taken by a packet coming in should be the same as that which was taken by the corresponding packet going out. This might not always happen in the topology you desire. Configuring Load Balancing and Redundancy with PIX firewalls is pretty different to doing the same using routers. To build redundancy, you will need to deploy 2 PIX firewalls in something called a failover pair. To do load balancing, you will need to configure the perimeter routers for the same or use PIXOS version 6.3, run OSPF and use Equal Cost Multipath Routes (ECMP). You can then load balance among a maximum of three peers on a single interface. More information on ECMP is available at http://www.cisco.com/univercd/cc/td/doc/product/iaabu/pix/pix_sw/v_63/config/bafwcfg.htm#1112559.
We have configured the outside and inside Interface with official ipv6 adresses, set a default route on outside Interface to our router, we also have definied a rule , which also gets hits, to permit tcp from inside Interface to any6.
In Syslog I also se...