While inline as you show would work (and is arguably more secure), some folks prefer to have the appliance's interfaces both connected to the internal switch on an "inside" and "outside" VLAN.
That is a bit easier to implement and, should it ever need to be taken offliner it can be done with simple switch configuration vs. moving cables.
I wonder if you also need to protect a DMZ with IPS?
As Marvin said, injecting an IPS inline to the path serves as the best protection as each every traffic in the path would be analyzed. The only issue with your IPS model accompanied with inline mode is, there is a lack of hardware inline bypass. But , it supports software bypass.
yes y right, 2 Internet router (3825) 2 asa 5520 2 ips 4240 2 core 4500, acting as core
Pls vivek can u draw the topology for me for the IPSs,routers,ASAs at the Internet edge that describe the physical connectivity of the devices
frankly speaking i didn't find diagram matching the described topolgoy so i seeking ur help