The Medium Network WAN

The SMR Blueprint actually does not address this module in much detail, but there isn't a great deal to the module: an ingress router that connects directly from the Frame Relay/ATM network to the Campus module. It serves to provide ingress/egress filtering, QoS management, and routing protocol updates with peers beyond this network. The filtering mitigates against IP spoofing, and access controls on the router protect it from unauthorized access.

If there is some concern regarding the confidentiality or privacy that is actually obtained over the private circuits, an alternative would be to encrypt data transiting the WAN (use IPSec tunnels). Likewise, if the ACLs seem insufficient for the traffic encountered , a stateful firewall could be added to the router (via the Firewall Feature Set).