On 23 Nov 1997 22:55:06 -0000 
 explorer@flame.org wrote:

 > When I turn on PMTU discovery, I get lots of clutter:
 > 
 > Destination        Gateway            Flags     Refs     Use    Mtu  Interface
 > pm300-36.tr.net-li near-gw.cygnus.com UGHD        0      247   1006  de0
 > pm300-39.tr.net-li near-gw.cygnus.com UGHD        0      224   1006  de0
 > pm301-14.tr.net-li near-gw.cygnus.com UGHD        1     2148   1006  de0
 > pm301-29.tr.net-li near-gw.cygnus.com UGHD        0     4226   1006  de0
 > pm301-46.tr.net-li near-gw.cygnus.com UGHD        0      405   1006  de0
 > 
 > Note that only one of these hosts is really in use.  Shouldn't
 > the others expire when the reference count reaches zero, or
 > at least after a timeout after the ref count reaches zero?

Yes, they should expire, like ARP entries do.  However, the ARP entries
are currently special-cased in the routing code.  Kevin has plans to
generalize route timers, but that's a bit of work.  So, basically, this
is a known bug, and one of the reasons PMTU discovery is disabled by
default.

Jason R. Thorpe                                       thorpej@nas.nasa.gov
NASA Ames Research Center                            Home: +1 408 866 1912
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