I have a Cisco 1700 series router and a PIX 506 configured on the network. Both devices have interfaces directly connected to the LAN and WAN.
Although I would like to configure the PIX as the default gateway I am unable to due to the fact that there are routes on the 1700 router that wouldn't be accessible to the clients (same interface traffic on the PIX etc). But at the same time I would like all internet traffic to pass via the pix and the GRE VPN tunnel traffic to pass via the router. The CPU utilisation is often quite high on the router due to the GRE VPN traffic, which is why I want to avoid passing general internet traffic through it.
I have configured the router as the defatlt gateway, however, I have changed the default route on the router to use the PIX. My question is this, is there a performance issue with this setup? My understanding of this is that the router should send an ICMP redirect for all the internet traffic which should then pass via the PIX? If the router is running particularly slow, is this setup going to impact general internet traffic?