Subject: RE: [P2Prg] RE:MANETS and P2P

From: "Ayyasamy, Senthilkumar \(UMKC-Student\)" <[email-masked]>
Date: Sat, 16 Aug 2003 06:18:22 -0500

>I'm not sure that DHTs and MANETS have a very good fit. 

DHT is not something new. The concept was originally introduced 
in landmark hierarchy for ad-hoc networks. Back in 1980s, LH was 
proposed by Paul Francis for self-configuring an ad-hoc network
into a routing hierarchy. It employs a function (assured dest
binding- ADB) to map the identifier to address; which is 
essentially a DHT. Some recent MANET routing proposals achieve 
scalability by way of landmark routing (e.g.LANMAR). 

The MANET WG has adapted two routing proposals (AODV/DSR);which 
suffers from scalability problems. DHT can provide indirection
service to achieve scalability. 

>This is because DHTs generally require that every node can address 
>every other node, in principle. In a MANET direct addressing 
>is only possible for individuals within broadcast range of each other,
>which may or may not be the individuals to whom you need to forward 
>your message for DHT routing.

DHT based overlay routing delivers requests for a given key to the 
node _currently_ responsible for that key. So, assumption is that 
their is NO permanent mapping of keys to nodes. Similar to multi-hop 
hierarchical routing done in MANETS, routing proceeds in a multi-hop 
fashion. Also, nodes maintain address for  only a small set of 
neighbors, and routes messages to the neighbor that is closer to the 
destination. So, the base message forwarding principle is same for 
both DHT-based  and MANET-based multi-hop routing.

> Keen to hear if you've found a way round this, though ;) We could 
> try it out with  SWAN (our hash-based routing mechanism, see 
> http://www.cefn.com/cefn/index.php?inventor), and the MANET 
> simulator we have.

Purdue has simulation results and work-in-progress prototype for DHT 
(pastry) + DSR = Dynamic P2P source routing. 

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From: Scott Michel <[email-masked]>
Date: Tue, 19 Aug 2003 10:53:08 -0700

You can go back even further into hypercube routing. DHTs advance science by 
routing on digit groups instead of single bits.

-scooter

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From: "Serguei Osokine" <[email-masked]>
Date: Thu, 21 Aug 2003 22:21:40 -0700

On Saturday, August 16, 2003 Ayyasamy, Senthilkumar wrote:
> Back in 1980s, LH was proposed by Paul Francis for 
> self-configuring an ad-hoc network into a routing
> hierarchy.

	Do you know if the original landmark hierarchy
paper can be found anywhere on the net? All I seem to
find is references...

	Thanks -
	Oso.
	21 Aug 2003.

[email-masked]

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From: Scott Michel <[email-masked]>
Date: Fri, 22 Aug 2003 14:38:25 -0700

It was originally published as:

P. F. Tsuchiya, "The landmark hierarchy: A new hierarchy for routing in very 
large networks," ACM Computer Communication Review, vol. 18, no. 4, August 1988.

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From: Scott Michel <[email-masked]>
Date: Fri, 22 Aug 2003 14:48:55 -0700

IIRC, the original paper wasn't proposing an ad hoc routing system (but it's 
been a while since I've looked at it.) Mario Gerla and his lab did some 
relatively recent research into landmark routing applied to ad hoc networks, 
with mixed results.

-scooter