Subject: Re: Message aggregation?

From: [email-masked]
Date: Fri, 10 Sep 1999 09:33:17 -0700

*> From [email-masked] Tue Sep  7 11:21:41 1999
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  *> Date: Tue, 07 Sep 1999 17:31:42 +0200
  *> To: [email-masked]
  *> From: Gume Gabor Feher <[email-masked]>
  *> Subject: Message aggregation?
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  *> Hi!
  *> 
  *> I measure RSVP performance with the latest Linux ISI implenetation. I found 
  *> that if a refresh message hits the router on a port, then it is emitted 
  *> more later on the other port.
  *> 
  *> Does RSVP play with refresh messages? Is it some kind of aggregation? I 
  *> suspect it. Even with PATH messages that not addressed to the router.
  *> 
  *> If I measure new reservation setups, then this effect does not apear at all.
  *> 
  *> Any help?
  *> Gume
  *> 

This is a feature of RSVP.  Refresh messages do not travel end-to-end.
Each hop can independently determine the appropriate refresh interval
for that hop, so each hop clocks refreshes out as it sees fit.
Furthermore, reservation refreshes necessarily are unsynchronized
across hops because of the necessity of merging.

State *changes* -- adding, modifying, or tearing down state -- should
immediately be forwarded (though not necessarily to the end, because
of merging); but normal refreshes are not.

Bob Braden