On Tue, Nov 25, 2008 at 3:06 PM, William Herrin <[EMAIL PROTECTED]> wrote: > Lets look at it a little more concretely: > > Machine 1 has locators A, B and C. > Machine 2 has locators D, E. > > The path from E to B is broken and delivers no packets. The others are > working normally. > > So, machine 1 sends a sequence of packets. They travel: A->D, B->E, > C->F, A->E, B->F, C->D and so on. The acks and any payload from > machine 2 come back D->A, E->B (dropped), D->C, E->A, D->B, etc.
That would be A->D, B->E, C->D, A->E, B->D, C->E and so on. I originally gave machine 2 three locators but figured it would make a better example if the locators were mismatched. > Over time, machine 1 sees a roughly even spread of lost packets > because because the acks don't come back when sent on the E->B path. > Since the spread is even, no path gets a preference over the other. > > At the same time, machine 2 notices that packets sent E->B never come > back and it notices that packets acked with the E->B link are > retransmitted by the source. It depreferences the EB pair so that > they're used less often until they reach some threshold and are cut > entirely due to being non-operable. > > Granted the system has a mildly stochastic nature, but it should > converge on the "best" working paths for any given communication > session. > > Of course if E->B is less broken and actually returns an unreachable > message the algorithm can shortcut and eliminate that path from use > immediately. -- William D. Herrin ................ [EMAIL PROTECTED] [EMAIL PROTECTED] 3005 Crane Dr. ...................... Web: <http://bill.herrin.us/> Falls Church, VA 22042-3004 _______________________________________________ rrg mailing list [email protected] https://www.irtf.org/mailman/listinfo/rrg
