Subject: [P2PSIP] comments on using DHTs in wireless ad hoc networks

From: "Victor Pascual Ávila" <[email-masked]>
Date: Tue, 20 Nov 2007 19:11:13 +0100

Hi all,
In "draft-bryan-p2psip-app-scenarios-00.txt", section 4.2 and 4.2.1.
identifies  "Ad-Hoc and Ephemeral Groups" application scenarios, and
can be read:

"Examples of such environment are isolated wireless ad-hoc networks
with no connection to the Internet or ad-hoc networks with limited
connectivity to the Internet in situations like outdoor public events,
emergencies, and battlefields."

In "draft-ietf-p2psip-concepts-01", section 5.1 describes "The
Distributed Database Function", and can be read:

"A class of algorithms known as Distributed Hash Tables
<http://en.wikipedia.org/wiki/P2P_overlay> are one way to implement
the Distributed Database.  In particular, both the Chord and Bamboo
algorithms have been suggested as good choices for the distributed
database algorithm.  However, no decision has been taken so far."

Problem of implementing a distributed hash table in wireless ad hoc
networks is well-known. Scarceness of resources and node mobility turn
routing into a problem.

Is there a consensus on using the same type of "Distributed Database
Function" (e.g. DHT) in all application scenarios? Are other solutions
or DHT adaptations (e.g. CHR) considered depending on application
scenario requirements?

Thanks and sorry if this was already discussed,
-- 
Victor Pascual Ávila
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---

From: <[email-masked]>
Date: Mon, 26 Nov 2007 12:18:24 +0200

Hi Victor

>Are other solutions or DHT adaptations (e.g. CHR) considered depending on application scenario requirements?

Yes, you are right DHTs may not be optimal for small ad-hoc overlay networks. Depending on the scenario it may be easier and more efficient (overhead) to implement an unstructured overlays.
 
The P2PP allows for unstructured overlays as well.

Marcin
 
>-----Original Message-----
>From: ext Victor Pascual Ávila [mailto:[email-masked]] 
>Sent: 20 November, 2007 20:11
>To: [email-masked]
>Subject: [P2PSIP] comments on using DHTs in wireless ad hoc networks
>
>Hi all,
>identifies  "Ad-Hoc and Ephemeral Groups" application 
>scenarios, and can be read:
>
>"Examples of such environment are isolated wireless ad-hoc 
>networks with no connection to the Internet or ad-hoc networks 
>with limited connectivity to the Internet in situations like 
>outdoor public events, emergencies, and battlefields."
>
><http://en.wikipedia.org/wiki/P2P_overlay> are one way to 
>implement the Distributed Database.  In particular, both the 
>Chord and Bamboo algorithms have been suggested as good 
>choices for the distributed database algorithm.  However, no 
>decision has been taken so far."
>
>Problem of implementing a distributed hash table in wireless 
>ad hoc networks is well-known. Scarceness of resources and 
>node mobility turn routing into a problem.
>
>Is there a consensus on using the same type of "Distributed 
>Database Function" (e.g. DHT) in all application scenarios? 
>Are other solutions or DHT adaptations (e.g. CHR) considered 
>depending on application scenario requirements?
>

---

From: "Mosiuoa Tsietsi" <[email-masked]>
Date: Mon, 26 Nov 2007 15:09:33 +0200

Hi all,

At MP2P Pisa '06, Heer et al presented their ideas on adapting DHTs for
MANETs, by building a DHT over a MANET underlay.  I didn't get the paper,
but I do have a copy of the slides they presented, so I may have this
muddled up, but it seems like they based their design on the need to
compensate for the cost of redundancy and overlay maintenance, by allowing a
single MANET to host several smaller but merged DHT rings, the goal being to
establish as few DHT connections as possible per ring.  They seemed to
indicate that it's possible but there are difficulties in working with two
heterogeneous routing layers.

Mos

On Nov 26, 2007 12:18 PM, <[email-masked]> wrote:

> Yes, you are right DHTs may not be optimal for small ad-hoc overlay
> networks. Depending on the scenario it may be easier and more efficient
> (overhead) to implement an unstructured overlays.
>