Han
How can we possibly know since you don't tell us what the setup is and personally i have no idea what the E-Commerce module is ???
As a general answer to your question. If you put the exposed hosts into a separate vlan you then mitigate L2 DoS attacks as the packets would need to be L3 switched to get to the hosts. You could also use acls on the vlan interfaces to limit the traffic.
That is about all that can really be said based on the description you have given.
Jon
