ZyXEL Communications X6004 Manual Do Utilizador

X6004 User’s Guide

This chapter shows you how to combine two or more X6004s to expand your IP PBX 
capabilities and utilize a failsafe mechanism in case of a breakdown. 

A ZyStack is the aggregation of multiple X6004s under a single management IP address. A 
ZyStack provides two major advantages. Firstly, it allows you to pool the resources of 
individual X6004s. Secondly, it provides a failsafe mechanism in case of a breakdown of one 
of the X6004s in a ZyStack.
When you create a ZyStack, the X6004s can take on a role of a master or a slave. There can 
only be one master X6004. You can manage the configuration of the master and slave X6004s 
by logging into the LAN or WAN IP address of the master X6004. 

In order for ZyStack to work you must follow these guidelines:

• All the X6004s should use the same interface, either LAN or WAN, to create a ZyStack. 

The setting on the master X6004 determines which interface the X6004s should use.

• All the X6004 should be on the same subnet. This is necessary for the X6004s to be able to 

backup each other. The failsafe mechanism utilizes IP alias. IP alias allows the X6004 to 
communicate via two IP addresses. The first is the IP address assigned to the X6004 itself 
and the second is the IP address of the X6004 that has failed. This feature is limited to a 
single routing domain.  

In the active mode failover all the X6004 participating in the ZyStack are also actively 
participating in the processing of phone calls. The ZyStack forms a ring with each X6004 
serving as a backup for the X6004 one step higher in its hierarchy. The hierarchy is organized 
in the order that each X6004 joined the ZyStack. The first X6004 is the master and it is backed 
up by the X6004 that was the second member of the ZyStack. The second member is backed 
up by the third and so on. Finally, the master serves as a backup to the last member to join the 
ZyStack. The following figure illustrates the active mode failsafe.