Hi Philip,
Thank you very much!
With your suggestion, I furthered tried the lossy model to output a loss topology of a 10 by 10 grid, with 50 foot spacing, and change the loss rate to be 0.0, and write it to the file "10_10_50_lossless.nss". I hope to achieve the effect that every node has at most 4 neighbors (all neighors are of no communication error) so that the interference in the network will be less and hence has the property of scalability.
The .nss file is of the form:
0 0 0.0 0.0 0.0
0 1 0.0 0.0 0.0
0 10 0.0 0.0 0.0
1 0 0.0 0.0 0.0
1 1 0.0 0.0 0.0
1 2 0.0 0.0 0.0
1 11 0.0 0.0 0.0
0 1 0.0 0.0 0.0
0 10 0.0 0.0 0.0
1 0 0.0 0.0 0.0
1 1 0.0 0.0 0.0
1 2 0.0 0.0 0.0
1 11 0.0 0.0 0.0
...
However, when i run TinyDB with 30 nodes with "./build/pc/main.exe -r=lossy -pf=10_10_50_lossless.nss 30", the parents of all nodes are 0xffff (broadcast address), so they assume the network topology hasn't been initialized? After around 2 minutes, it seems that a topology has been set up and parent of node are of a less than 30 value. However, the parent-child relationship doesn't agree with the topology file i put in. For example, node 24's parent is 20, while node 23's parent is 9, and node 28's parent is 0.
I am wondering why the topology file doesn't take effect. To confirm that the topology file has actually been read, i tried to give an illegal filename under "pf=" and error messages come out. Hence, i assume that the topology file has been read...
Why the toplogy file doesn't take effect? How should i simulate a network in which only the nodes within 50 feet of each other can communicate without affecting other nodes out of range to receive packets and drop packets? Any help is greatly appreciated!
Best wishes,
Shili
On 12/6/05, Philip Levis <[EMAIL PROTECTED]
> wrote:
On Dec 5, 2005, at 7:51 AM, Shili Xiang wrote:
> Dear all,
> I am trying to run TinyDB in TOSSIM, but when i submit query to a
> network with even just 20 nodes, the query fail to be disseminated
> throughout the network to be executed correctly, with errors below:
> 10: Error : 14 at line 955
> 10: Error : 14 at line 955
> Error 14 stands for err_MSF_ForwardKnownQueryBusy, which is due to
> radio busy. So i am thinking that maybe i didn't set radio model
> appropriately.
Or maybe TinyDB is trying to send packets faster than the radio can?
If you have 20 nodes in a cell, then each node can send ~2 packets
per second. When TinyDB tries to flood a query, it could definitely
run into a situation where it has a big surge in traffic.
>
> Hence, it seems to me that in "lossy" model, the radio of any node
> can still reach any other node, and the lossy.nss is defining
> whether the packet transmission is successful or not.That is,
> although the lossy model file defines the topology, it doesn't mean
> that the radio can only reach the nodes that are within the
> interference range.
>
It all depends on how far apart the nodes are spaced. I think the
manual goes into this. Nodes < 50 units apart can hear each others
signals, although at 50 there will be 100% loss.
Phil
-------
"We shall not cease from exploration
And the end of all our exploring
Will be to arrive where we started
And know the place for the first time."
- T. S. Eliot, 'Little Gidding'
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