TMS zl Management and Configuration Guide ST.1.2.100916

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Overview
HA Clusters
Figure 1-21. Active-Standby Mode
HA Cluster Operation Rules
The TMS zl Modules in an HA cluster synchronize their connection state
information by sending messages over the HA VLAN, which must be dedicated
to HA traffic. The HA VLAN is configured on the modules’ internal port 2,
which must be dedicated to HA traffic.
The modules in an HA cluster can be installed in the same switch chassis or
in different switch chassis.
If the modules are installed in different switches, the two switches must have
a Layer 2 connection on the HA VLAN. HP recommends that the switches be
directly connected with redundant links. This precaution minimizes the risk
that two functioning modules lose their connection with each other, which
can cause both to assume the master role, creating problems in filtering and
forwarding traffic. In addition, both host switches must support all TMS
VLANs. Otherwise, the participant cannot properly provide failover.