On Tue, Nov 25, 2008 at 1:04 PM, Luigi Iannone <[EMAIL PROTECTED]> wrote: > symmetric routing: your data packet and your ack do not pass necessarily > through the same LOCs (which limits the capacity of discover the broken > link). Am I wrong?
Luigi, I had not intended that the acks be required use the same locator set as the forward traffic, no. What makes you think this impairs broken link discovery? 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. 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. What's the problem? Regards, Bill Herrin -- 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
