Figure 251 Zystack - Standby Mode - ZyXEL Communications X6004 User Manual

Chapter 22 ZyStack

Figure 251 ZyStack - Standby Mode

Again, the backup cannot recreate the extensions created for analog phones of the X6004 that
is down, nor can it recreate the outside lines via the FXO ports. FXS and FXO links are
physical connections to an X6004 and can't be duplicated by a backup X6004. FXS extensions
and FXO connections must be recreated in order to be used again.
ZyStack Internal Call Routing
When an IP phone is a SIP client of one X6004 (A in the figure) and it calls a telephone that is
a SIP client of another X6004 (B in the figure). The default behavior of the X6004 (A) is to
process the call and connect it to the X6004 (B) on which the SIP client is configured. This
telephone call is illustrated by the solid line in the following figure. Note that the processing
resources of both X6004s are being utilized throughout the duration of the call.
The X6004s can handle internal calls more efficiently if you specify the local subnets which
can connect to other ZyStack members. The dotted line shows the same phone call after it has
been redirected to X6004 B. In this scenario the subnet 192.168.1.0/24 was configured as a
local subnet. When A receives a call from a SIP client that matches the local subnet and the
destination of the client's request is a phone connected to another X6004 (B), it then redirects
the call to B.
Figure 252 Internal Call Routing
192.168.1.1
192.168.1.2
A
B
192.168.1.102
192.168.1.101
In this first example all the devices reside on the same subnet. A single subnet configuration is
recommended for ease of use and management. This, however, is not always possible in your
network.
275
X6004 User's Guide