The Jargon File (version 4.4.7, 29 Dec 2003):

network meltdown
 n.

    A state of complete network overload; the network equivalent of thrash
    ing. This may be induced by a Chernobyl packet. See also broadcast storm
    , kamikaze packet.

    Network meltdown is often a result of network designs that are optimized
    for a steady state of moderate load and don't cope well with the very
    jagged, bursty usage patterns of the real world. One amusing instance of
    this is triggered by the popular and very bloody shoot-'em-up game Doom on
    the PC. When used in multiplayer mode over a network, the game uses
    broadcast packets to inform other machines when bullets are fired. This
    causes problems with weapons like the chain gun which fire rapidly ? it can
    blast the network into a meltdown state just as easily as it shreds
    opposing monsters.


The Free On-line Dictionary of Computing (30 December 2018):

network meltdown
meltdown

    (By analogy with catastrophic failure of a
   nuclear reactor) An event that causes saturation, or near
   saturation, of a network.  Network meltdown usually results
   from illegal or misrouted packets (see Chernobyl packet)
   and typically lasts only a short time.  It may also be caused
   by a hardware fault.  It is the network equivalent of
   thrashing.

   [Jargon File]

   (2004-02-17)