from
The Free On-line Dictionary of Computing (8 July 2008)
hello packet
<networking, communications> An {OSPF} {packet} sent
periodically on each {network interface}, real or {virtual},
to discover and test connections to neighbours. Hello packets
are multicast on physical networks capable of {multicasting}
or {broadcasting} to enable dynamic {router} discovery. They
include the parameters that routers connected to a common
network must agree on.
Hello packets increase network resilience by, e.g., allowing a
router to establish a secondary connection when a primary
connection fails.
(1999-11-02)