VERITAS Storage Foundation 4.1 for Oracle RAC HP Serviceguard Storage Management Suite Extracts, December 2005

Storage Foundation for Oracle RAC Communications
Storage Foundation for Oracle RAC Communications
The communications package for Storage Foundation for Oracle RAC consist of LLT and
GAB.
Low Latency Transport (LLT)
LLT provides fast, kernel-to-kernel communications, and monitors network connections.
LLT serves as a high performance replacement for the IP stack and runs directly on top of
the Data Link Protocol Interface (DLPI) layer. The use of LLT rather than IP removes
latency and overhead associated with the IP stack. LLT has several major functions.
Traffic Distribution
LLT distributes (load-balances) inter-node communication across all available private
network links. All cluster communications are evenly distributed across as many as eight
network links for performance and fault resilience. If a link fails, LLT redirects traffic to
the remaining links.
Heartbeat
LLT is responsible for sending and receiving heartbeat traffic over network links. This
heartbeat is used by the Group Membership Services function of GAB to determine
cluster membership.
6 VERITAS Storage Foundation for Oracle RAC Installation and Configuration Guide