Chapter 1 Introducing the ISG50
ISG50 User’s Guide
30
provides the VoIP services listed in the previous scenario, and the USG provides the security
services. Here is an example.
Figure 3 DMZ Installation
1.1.3.3 Parallel to a USG
Connect the ISG50 to the Internet and a USG model’s LAN to give the VoIP a physically separate
Internet connection to keep bursts of data traffic from impacting voice quality. The ISG50 provides
the VoIP services listed in the previous scenario along with firewall protection and VPN and WAN
fail-over for the VoIP services. The USG provides additional WAN fail-over protection for the VoIP
services. Here is an example of using the ISG50 along with a USG.
Figure 4 Installation Parallel to a USG
FAX
ITSP
PSTN/ISDN
ISG
DMZ
LAN
A
C
Headquarters
B
D
WAN1
WAN2
USG
FAX
ITSP
PSTN/ISDN
ISG
DMZ
LAN
A
C
Headquarters
B
D
WAN1
WAN2
USG
WAN2
WAN1
