[SensorNetArch] Two idea for today

[Cheng Tien Ee]

Isn't Jerry working on something very similar to this right now? Perhaps 
he would like to discuss what he's doing?


David Culler wrote:

> The degree of flexibility in this naming scheme is the size of each 
> sibling field >= ceiling(number of children).  For any subtree, the 
> root of the subtree can take on children as long as the number doesn't 
> exceed the field size that the root of that subtree established.  If 
> that bound is exceeded, the entire subtree must be renamed.
>
> Subtree renaming is always possible without affecting the rest of the 
> tree.
>
> A parent change causes the entire subtree to be renamed.
>
> Gilman Tolle wrote:
>
>> So, you've built this trivial network. C's name is then 011001. How,
>> then, will this name remain valid when the network becomes
>>
>> D -> B -> C
>> 10   10    01
>>
>> C's routable name is now 101001, and any messages sent to 011001 will
>> be delivered to the wrong node.
>>
>> I'm definitely interested in finding a way around this...I just don't
>> see it right now.
>>
>> Perhaps nodes could "cover for each other", by maintaining some state
>> about each others' previous child numbers. Or, parents could maintain
>> some "historical" references, to delay the need for renumbering until
>> it is absolutely necessary.
>>
>> But, if the messages to be routed are infrequent enough, adaptivity is
>> not really necessary. A rough tree could be built quickly, and then
>> used to route messages, and then a new tree could be built again
>> later.
>>
>> Gil
>>
>> On Mon, 07 Mar 2005 17:10:16 -0800, Philip Levis 
>> <pal at eecs.berkeley.edu> wrote:
>>
>>> On Mar 7, 2005, at 4:17 PM, Gilman Tolle wrote:
>>>
>>>
>>>> Because this is such a popular idea (I've worked on it also), the
>>>> question then becomes "why aren't we using it?".
>>>>
>>>> Establishing the names is easy -- just build a tree and set up the
>>>> numbering. Adaptation is hard. Responding to the fact that changing a
>>>> parent requires renaming all descendants, and changing the number of
>>>> bits used to represent children requires renaming all children's
>>>> descendents.
>>>>
>>>
>>> While adaptation can cause a node's name to change, it might not need
>>> to be aware of this, as its name is in relation to another. E.g.,
>>> imagine this trivial network:
>>>
>>>  A -> B -> C
>>> 01   10   01
>>>
>>> Where A has root name 01, B has child name 10 and C has child name 01.
>>>
>>> All C needs to know is that it is a child of B and its name is 01. If B
>>> changes its parent (say, to D), then C does not need to know this. When
>>> does C need to know its network-wide name? All routing/naming decisions
>>> are resolved locally... generating a node's fully name is just storing
>>> the route taken up the tree.
>>>
>>> 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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