Re: NHRP specification comments

["James V. Luciani" <[e-mail]>]

> Section 6.2.1 ("Caching Requirements") - in the paragraph relating to
> caching at "Transit NHSs" - currently this says that cache information
> MUST be discarded when it has exceeded its holding time.  It also says 
> that this information may be used to form a reply to a non-authoritative 
> request. 
> 
> I believe that the negative effects of caching at intermediate NHSs can 
> be substantially reduced if hold time returned in a non-authoritative
> response MUST be the result of decreasing the original hold time by the
> elapsed time since initially caching the information.  This information
> is either immediately available or easily derivable (depending on your
> implementation) and limits the length of time that stale information can
> persist in the system to approximately that intended by the original
> responder.
> 
> I would be interested in whether or not this is a commonly-held opinion.
Hmmm...  I hope so but you have a good point...  I should make this explicit.
You should return the remainder of the Holding time here.  WE could waffle on
this and say that you send only "holding time you want"/2 in registration
so that you have worst case of 
2*"holding time specified"+reply delay
but I think that is kinda hokey...  So I am inclined to just say return
the timer value remaining.
> 
> Section 6.2.2 ("Dynamics of Cached Information") contains a note (at the
> end of the subsection entitled "NBMA-Connected Destinations" that might
> be interpreted as meaning that it is okay to cache information contained
> in a Next Hop Resolution Request (as opposed to Reply) because it is 
> considered stable.  Is this what you mean to imply here?
No. You SHOULD NOT cache source information. If you cache source information 
then expect to get burned eventually.  Thanks for pointing this out.  This
is along the lines of the discussions of a few weeks ago on the list
so I will include this tidbit with the information from those discussions.

--JIm