VCS uses two components, LLT and GAB, to share data over private networks among systems. These components provide the performance and reliability that VCS requires.

LLT (Low Latency Transport) provides fast, kernel-to-kernel communications, and monitors network connections.

GAB (Group Membership and Atomic Broadcast) provides the global message order that is required to maintain a synchronized state among the nodes. It monitors disk communications such as the VCS heartbeat utility. The /etc/gabtab file is the GAB configuration file.