Step 3 – plan your configuration
Suggested Deployment
A typical 4300T installation uses the integrated CSU/DSU in the 4300T to terminate a
T1 WAN connection. The LAN ports of the 4300T are then used for connection to
PCs, servers, IP phones or other layer 2 ethernet switches. The diagrams below
show typical deployments for both service provider and enterprise applications.
In these examples a single public IP address on the WAN is used to proxy for all of
the IP phones and to route to multiple PC’s installed on the LAN.
The 4300T provides the following services:
•
WAN/LAN IP routing
•
NAT/PAT translation for IP phones and PC’s. This allows a single public IP
address to be used on the WAN link to represent all of the private IP
addresses assigned to the LAN IP phones and PC’s.
•
A “VoIP” aware firewall. A full layer 7 gateway for voice traffic and a stateful
packet inspection firewall for data traffic.
•
Traffic shaping and priority queuing to guarantee the quality of VoIP traffic.
These mechanisms protect voice and data traffic from contending for the
same network resources to guarantee low latency and the highest call quality
possible for VoIP traffic. At the same time they ensure the best utilization of
WAN bandwidth by enabling data traffic to burst up to full line rate in the
absence of voice calls. Precedence is given to traffic for the range of
addresses reserved for the IP phones.
•
Call Admission Control (CAC). CAC uses a deterministic algorithm to decide
when there are insufficient network resources available to adequately support
new calls and then return the equivalent of a “fast busy” to new call requests.
