User manual

4300T User Manual Edgewater Networks, Inc.
Version 1.7 12
Configuration Guide For IP Centrex Applications
A typical 4300T installation for an IP
Centrex application requires no
external router or firewall. The 4300T
WAN port is connected directly to the
T1/E1 line and the LAN port(s) are
connected directly to enterprise devices
and/or Ethernet switches.
VoIP signaling is performed in the
service provider network via a
softswitch and the 4300T acts as a
proxy for the voice devices installed in
the enterprise LAN. In this
configuration a single public IP address
is used to proxy for all of the IP phones
and to route to multiple PC’s installed
on the LAN.
The 4300T performs the following functions in this application:
 WAN/LAN IP routing.
 Traffic shaping and priority queuing to guarantee high quality voice 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 automatically given to traffic coming
from IP phones and other devices using the 4300T’s Application Layer
Gateway function.
 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.
 Static NAT entries. This enables the customer to use a WAN public IP address
for data servers (web, mail, ftp, etc.) connected behind the 4300T. These
servers can then be configured with private IP addresses for additional
security.
 A “VoIP” aware firewall. A full Layer 7 gateway for voice traffic and a stateful
packet inspection firewall for data traffic.
 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.
 DHCP server and TFTP relay. These features are used to simplify and
expedite the IP configuration of phones and PC’s. This also includes VoIP
signaling gateway information (MGCP, SIP, H.323 and SCCP).
 Call quality monitoring (using MOS, jitter, latency, packet loss and much
more) and test tools.
 VoIP survivability. Provides call switching to an LAN based PSTN gateway
during WAN outages.