Polycom 4300T Benutzerhandbuch

User Guide V

2

IU 4300T Converged Network Appliance

3 - 6

• 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 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.

• 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 and test tools.

• VoIP survivability.  Provides call switching to an LAN based PSTN 

gateway during WAN outages.

System Configuration

configure LAN/WAN interface

Yes

set ethernet link rate

Optional

enable the DHCP server

Optional but 
recommended

configure SNMP

Optional

VoIP Configuration

enable the VoIP ALG

Yes

configure a VoIP subnet route

Optional

Data Networking Configuration

dynamic NAT

Optional but 
recommended

static NAT

Optional