I don't think 802.15.4 allows nodes to form routing tables and I don't think Acks are implemented in 802.15.4, only error checking and destination checking.
On Tue, Sep 22, 2009 at 8:37 PM, Varun Jain <[email protected]> wrote: > I think IEEE802.15.4 already sends beacons to its neighboring nodes to > form their Routing tables, I am digging into the internals to do that… Also > I think software Acks are already implemented when packets are delivered > from the originating node to the next hop… > > > > Your example makes perfect sense because the other way I was thinking of > implementing it was using Collection in my application where I can send a > packet (with just uint8_t data) every few minutes. Then if the ROOT does not > see a packet from a particular node for a particular time, say continuously > for 30 minutes, then it can inform the User/Manager about the node being > Dead….. but I want a more instant reaction if the node is being turned off. > This kind of application level implementation adds unnecessary memory usage > so I was wondering if it can be done from the already existing code > structure of MAC layer?? > > > > My testbed of 40 nodes is already sending 2 kinds of sensor data to the > Root node continuously but it is event/status driven so I can’t use those > data packets as a “status check” because sometimes status doesn’t change in > particular nodes for days… the problem is that we can’t really send a “power > off” status from the node that has turned off so it has to be done by a > neighboring node and I am pretty sure by working out from the Routing > tables…. > > > > Cheers, > > Varun Jain > > > > *From:* Mohammed Billoo [mailto:[email protected]] > *Sent:* Wednesday, 23 September 2009 10:15 AM > *To:* Varun Jain > *Cc:* [email protected] > *Subject:* Re: [Tinyos-help] Using CTP to detect Node Status?? > > > > Here's a suggestion, I don't know if it meets your requirements. What if > you not use CTP and just make your own app to check if nodes are alive or > not. Create two types of packets (three if you want to send actual data). > One packet should have a data field that has certain bytes (lets say decimal > 3). This packet is used to send acknowledgement requests and this packet at > a certain time interval. So, if a node wants to know which other nodes in > its neighborhood are alive, it sends this acknowledgment request. A node > receiving this packet checks this request using some sort of simple if > statement, and sends an acknowledgment, which tells the node that sent the > initial acknowledgment request that it is still alive. > > > > Then, you could do some sort of averaging to figure out that if an > acknowledgment was not received after a certain number of intervals, then > the node is probably dead. > > > > Let me know if that makes sense. > > > > Cheers, > > On Tue, Sep 22, 2009 at 7:35 PM, Varun Jain <[email protected]> > wrote: > > I need to tell the ROOT/BaseStation node in the network about a particular > node being turned off. As the neighboring nodes have information about a > particular node and they receive constant beacons from each other, I am > wondering that if I can work out that a beacon has not been received then > one of the neighboring nodes should be able to send a message to the Root > node telling that a node in its routing table is not there anymore. But then > due to changes in ETX values Nodes might be changing their Routing tables, > so a change in the Routing table entry in one of the neighboring nodes is > not a sure shot way to find out the status of nodes. If my reasoning is > correct, then how can we achieve this??? > > > > Cheers, > > Varun Jain > > > > *From:* [email protected] [mailto: > [email protected]] *On Behalf Of *Mohammed > Billoo > *Sent:* Wednesday, 23 September 2009 6:21 AM > *To:* [email protected] > *Subject:* [Tinyos-help] Using CTP to detect Node Status?? > > > > Hi, > > > > Do you want to tell the same node that it has been turned off or do you > want to tell another node in the network that a particular node has been > turned off ? I read the TEP on CTP and didn't see any form of Acks being > used so that you could determine whether a node is turned on or off based on > these Acks. Maybe you could integrate an Ack method with CTP to figure out > if a node is on or off. > > > > Regards, > > -- > Mohammed Billoo > > > > Hi, > > If I want to know that a node has been turned off in the network, is > there a way that the neighbor nodes can inform it?? I know there is an > application called "Antitheft" which uses sensors to do that but I do > not want to use sensors, I want to use the routing information available > with the neighboring nodes to inform this. I was thinking if it can be > done from within the CtpRoutingEngine???? > > > > To understand better about the CTP protocol, could someone explain what > can be possible effects of the "etx" bug fixed recently (Sep 21,2009) in > CtpRoutingEngine and CtpRoutingPacket if we do not commit the fix in our > code. I just want to understand the misbehavior that the bug can cause > (if not fixed) in the network?? > > > > Thanks, > > Varun Jain > > > > > -- > Mohammed Billoo > -- Mohammed Billoo
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