breath-of-life packet n. [XEROX PARC] An Ethernet packet that contains
   bootstrap (see {boot}) code, periodically sent out from a working
   computer to infuse the `breath of life' into any computer on the network
   that has happened to crash. Machines depending on such packets have
   sufficient hardware or firmware code to wait for (or request) such a
   packet during the reboot process. See also {dickless workstation}.

   The notional `kiss-of-death packet', with a function complementary to
   that of a breath-of-life packet, is recommended for dealing with hosts
   that consume too many network resources. Though `kiss-of-death packet'
   is usually used in jest, there is at least one documented instance of an
   Internet subnet with limited address-table slots in a gateway machine in
   which such packets were routinely used to compete for slots, rather like
   Christmas shoppers competing for scarce parking spaces.


Source: The Jargon File