On Fri, Jul 25, 2008 at 3:22 PM, fatima zohra <[EMAIL PROTECTED]> wrote: > > 2008/7/25 Omprakash Gnawali <[EMAIL PROTECTED]>: >> >> On Fri, Jul 25, 2008 at 7:37 AM, fatima zohra <[EMAIL PROTECTED]> >> wrote: >> > >> > >> > 2008/7/25 Omprakash Gnawali <[EMAIL PROTECTED]>: >> >> >> >> On Wed, Jul 23, 2008 at 11:45 AM, fatima zohra <[EMAIL PROTECTED]> >> >> wrote: >> >> > >> >> > >> >> > 2008/7/23 Omprakash Gnawali [EMAIL PROTECTED]: >> >> > >> >> >> >> >> >> If you put sequence numbers in the packet, you can find out which >> >> >> packets were not received. For example, you sent sequence numbers 1 >> >> >> through 10 but and received 1,2,3,4,6,7,8,9,10 then you know exactly >> >> >> how many packets were not received. >> >> >> >> >> >> - om_p >> >> > >> >> > actually this isn't my scenario; >> >> > here is an example of my protocol mechanism: >> >> > we assume Node1 neighbor of nodes 2 & 3, and these two nodes are >> >> > neighbors >> >> > of source S (S will send 10 msgs for example) >> >> > if 3 crashes so node 1 won't receive any more packets from 3. which >> >> > means if >> >> >> >> You said there is one source but why is node 3 sending packets? >> > >> > because node 3 will forward what the source is sending in order to reach >> > the >> > sink (let's say for example sink = node1 to make it easier) >> >> >> >> > S sends messages (from numSeq = 5 to 9) node A will never notice >> >> > that >> >> > he >> >> >> >> Node A is mentioned here for the first time. Is it node A or 1 or 2 or >> >> 3? >> > >> > sorry, it's node 1 (which isn't a "direct" neighbor to the source S) >> >> >> >> > missed the 5 last nodes (because he doesn't communicate with S >> >> > directly >> >> > , >> >> >> >> Nodes or packets? >> > >> > sorry again, it's "packets" >> >> >> >> > and node 3 is turned off for ever and node 2 won't help him to know >> >> > what >> >> > node 3 lost as messages (from S or other sources) because seq number >> >> > is >> >> > unique and different for each node (the 5th seqNum for node 2 may be >> >> > the >> >> > 1st >> >> > message of the source S) >> >> > now i wonna to calculate packet loss rate in my network since i have >> >> > a >> >> > set >> >> > of nodes who crash and will lose some sent messages. >> >> > am i clear now ? if yes, how to handle this situation. >> >> > thanks in advance. >> >> > best regards. >> >> >> >> Your description has some typos and could use some clarification. >> >> >> >> - om_p >> > >> > i mention in addition of what was said that: this simulation is done to >> > study the behavior of the network after some nodes crash. >> > so, first i choose some faulty nodes, then , turn them off for the rest >> > of >> > simulation (they won't receive any packet in the future). in the end of >> > my >> > simulation, i calculate my packet loss rate (i.e number of sent messages >> > but >> > not received by faulty nodes once they are stopped). >> > is it clear now ? >> >> Almost. >> >> So you have a topology that looks like this: S --> 3 --> 1 but 3 is >> turned off so 1 is not receiving any packets but you want to find the >> loss rate on the link 3-->1? >> >> - om_p > > that's it, > but S-->3-->1 is just a piece of my topology (i just noticed it to clarify , > my topology is larger than that). > let's work with this small scenario. > what's the way to find the packet loss rate ?
Considering your scenario and objective, you should have each node send packets periodically just for link estimation. Then you will be able to estimate link quality even in the absence of data packets. - om_p _______________________________________________ Tinyos-help mailing list [email protected] https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
