I have two cisco pix 515e in two different buildings. They do not have csu/dsu interfaces. They each have two ethernet interfaces. The ethernet interfaces go to cisco 2600 routers which has csu/dsu interfaces (not owned by us). At the core in each building we have Cisco 6509 Catalyst switches.The 6509 switches are directlyh connected to each other via gigabit fiber. We have a T1 in each building going to the internet. I need to know how to configure the cisco pixs or the cisco 6509s to use redundant routing in the event of a T1 failure. For example, if one T1 fails, I need the user to still be able to get out to the internet. Keep in mind we do not have access to the 2600 routers or their CSU/DSUs (They are the ISPS).