3Com NBX 100 Administrator's Manual - page 330
330
C
HAPTER
12: V
IRTUAL
C
ONNECTIONS
■
VTL connections cannot be configured to run through firewalls or NAT
routers.
■
When you calculate the number of devices on a system, do not
include the number of VTLs.
There are two implementation techniques you can use: unique extension
ranges (see the next section) or site codes (see
page 331
).
VTL Connections
Using Unique
Extension Ranges
If you can restrict the extension ranges on each of the systems so that
they do not overlap, you can configure the dial plans to route calls based
only on the extension that is being dialed. The caller does not have to dial
any digits to specify the site.
Assess your growth plans for each site to verify that as you add
telephones you do not exceed your defined extension ranges.
Figure 20
depicts a configuration that uses unique extension ranges.
Figure 20 Multi-site Network using Virtual Tie Lines
In the sample network shown in
Figure 20
, each site is set up to use a
unique range of telephone extensions. The dial plan on each of the
systems is configured so that whenever a call is made to an extension not
located at the local site, the system sets up a VTL connection to the
appropriate site.
To make a call to a user in Dallas, a user in Chicago dials a Dallas
extension (3000 through 3999). The dial plan on the Chicago system is
WAN
Chicago
System
Extensions
1000 – 1999
Atlanta
System
Extensions
2000 – 2999
Dallas
System
Extensions
3000 – 3999