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revision 1.88 by hemppah, Thu Feb 27 09:21:00 2003 UTC revision 1.89 by hemppah, Thu Feb 27 09:38:48 2003 UTC
# Line 234  Gnutella \cite{gnutellaurl} is well-know Line 234  Gnutella \cite{gnutellaurl} is well-know
234  other Peer-to-Peer networks, no Peer is more important than any other Peer in the network.  other Peer-to-Peer networks, no Peer is more important than any other Peer in the network.
235  The construction and maintenance of Gnutella network is extremely ad hoc, since participating  The construction and maintenance of Gnutella network is extremely ad hoc, since participating
236  peers can form the overlay network based on local knowledge. Figure \ref{fig:gnutella_overlay}  peers can form the overlay network based on local knowledge. Figure \ref{fig:gnutella_overlay}
237  illustrates how Peers can form an overlay network. Initially, peer 1 creates the overlay, since  illustrates how peers form an overlay network. Initially, peer 1 creates the overlay, since
238  it's the first participating peer. Then, repeatly new peers join the network and connects to  it's the first participating peer. Then, repeatly new peers join the network and connects to
239  other nodes in a random manner. Thus, gnutella can be considered as a \emph{random graph}.  other nodes in a random manner. Thus, gnutella can be considered as a \emph{random graph}.
240    
241    \begin{figure}
242    \centering
243    \includegraphics[width=6cm, height=6cm]{gnutella_overlay.eps}
244    \caption{Basic loosely structured overlay's ad hoc connectivity graph}
245    \label{fig:gnutella_overlay}
246    \end{figure}
247    
248    
249  In Gnutella, each participating peer maintains local index of its own shared content. Also,  In Gnutella, each participating peer maintains local index of its own shared content. Also,
250  each peer has a few connections to other peer, i.e., peer's \emph{neighbors}. Basic gnutella  each peer has a few connections to other peer, i.e., peer's \emph{neighbors}. Basic gnutella
251  data lookup works as follows: peer broadcasts a query request to its neighors, which in turn  data lookup works as follows: peer broadcasts a query request to its neighors, which in turn
# Line 249  $T$ (e.g., 7), where T is the system-wid Line 257  $T$ (e.g., 7), where T is the system-wid
257  are TTL hops away from the query originator will forward the query or respond to the query.  are TTL hops away from the query originator will forward the query or respond to the query.
258  In Gnutella network, search results are fast, because breadt-First traversal sends queries to  In Gnutella network, search results are fast, because breadt-First traversal sends queries to
259  every possible neighbor. On the other hand, this method wastes resources and doesn't scale well.  every possible neighbor. On the other hand, this method wastes resources and doesn't scale well.
260    Figure \ref{fig:gnutella_query} shows the query lookup process of Gnutella network.
261    
262    \begin{figure}
263    \centering
264    \includegraphics[width=8cm, height=6cm]{gnutella_query.eps}
265    \caption{Basic Gnutella query}
266    \label{fig:gnutella_query}
267    \end{figure}
268    
269  According to \cite{lv02searchreplication}, Gnutella's way to perform data lookups, \emph{flooding}, has  According to \cite{lv02searchreplication}, Gnutella's way to perform data lookups, \emph{flooding}, has
270  following limitations. First, choosing the approriate TTL in practice is not easy. If the  following limitations. First, choosing the approriate TTL in practice is not easy. If the
# Line 256  TTL is too high, query originator may un Line 272  TTL is too high, query originator may un
272  low, the query originator might not find the desired data even it's available somewhere  low, the query originator might not find the desired data even it's available somewhere
273  in the network. Second, there are many duplicate messages generated by flooding, especially  in the network. Second, there are many duplicate messages generated by flooding, especially
274  in high connectivity graphs. It is obvious that with these limitations, flooding creates  in high connectivity graphs. It is obvious that with these limitations, flooding creates
275  significant message processing overhead for each query. Furthermore, as a result,  significant message processing overhead for each query. Furthermore, flooding may increase
276  flooding may increase the load on participating to the point, where it has to leave the network.  the load on participating to the point, where it has to leave the network.
277    
278    
279    
# Line 267  and scalability. Adamic et. all \cite{ad Line 283  and scalability. Adamic et. all \cite{ad
283  networks\footnote{In power-law networks only a few peers have high number of neighbor  networks\footnote{In power-law networks only a few peers have high number of neighbor
284  links and major of peers have low nuber of neighbor links.} and they have found that by  links and major of peers have low nuber of neighbor links.} and they have found that by
285  instructing peers forwarding queries to select high degree peers the data lookup's  instructing peers forwarding queries to select high degree peers the data lookup's
286  performance increases signficantly. However, it's not clear whether this algorithm  performance increases signficantly. As a result, some of the most recent loosely
287  is scalable or not.  structured Peer-to-Peer system have adopted this method with some modifications
288  .  \cite{gnutella2url}, \cite{shareazaurl}, \cite{fasttrackurl}, \cite{morpheusurl},
289    \cite{kazaaurl}. Figures \ref{fig:gnutella_overlay_supernodes} and \ref{fig:gnutella_overlay_cluster}
290    illustrated two possible variations of power-law overlay networks. However, it's
291    not clear whether this algorithm is scalable or not, as majority of the query
292    request are sent only to the high degree peers, making them stress the overhead
293    of nearly entire system.
294    
295    
296  \begin{figure}  \begin{figure}
297  \centering  \centering
298  \includegraphics[width=6cm, height=6cm]{gnutella_overlay.eps}  \includegraphics[width=8cm, height=6cm]{gnutella_overlay_supernodes.eps}
299  \caption{Basic loosely structured overlay's ad hoc connectivity graph}  \caption{Power-law network overlay with super peers.}
300  \label{fig:gnutella_overlay}  \label{fig:gnutella_overlay_supernodes}
301  \end{figure}  \end{figure}
302    
303    \begin{figure}
304    \centering
305    \includegraphics[width=10cm, height=6cm]{gnutella_overlay_clusters.eps}
306    \caption{Power-law network overlay with 2-redundant super node clusters}
307    \label{fig:gnutella_overlay_cluster}
308    \end{figure}  
309    
310    
311    
312    
313    
314  power-law disribution  power-law disribution
# Line 360  Small worlds \cite{adamic99small} Line 388  Small worlds \cite{adamic99small}
388  \cite{nips02-Kleinberg}  \cite{nips02-Kleinberg}
389  \cite{ganesan02yappers}  \cite{ganesan02yappers}
390  \cite{gnutellaurl}  \cite{gnutellaurl}
391  \cite{gnutella2url}  
 \cite{shareazaurl}  
 \cite{fasttrackurl}  
 \cite{morpheusurl}  
 \cite{kazaaurl}  
392  \cite{jxtaurl}  \cite{jxtaurl}
393  \cite{jxtaoverview}  \cite{jxtaoverview}
394  \cite{botros01jxtasearch}  \cite{botros01jxtasearch}
# Line 375  Small worlds \cite{adamic99small} Line 399  Small worlds \cite{adamic99small}
399    
400  \subsection{Super peers and Super peer clusters}  \subsection{Super peers and Super peer clusters}
401    
 \begin{figure}  
 \centering  
 \includegraphics[width=8cm, height=6cm]{gnutella_overlay_supernodes.eps}  
 \caption{Loosely structured overlay's ad hoc connectivity graph with super nodes}  
 \label{fig:gnutella_overlay_supernodes}  
 \end{figure}  
402    
 \begin{figure}  
 \centering  
 \includegraphics[width=10cm, height=6cm]{gnutella_overlay_clusters.eps}  
 \caption{Loosely structured overlay's ad hoc connectivity with 2-redundant super node clusters}  
 \label{fig:gnutella_overlay_cluster}  
 \end{figure}  
403    
404    
405  \begin{figure}  
 \centering  
 \includegraphics[width=8cm, height=6cm]{gnutella_query.eps}  
 \caption{Basic Gnutella query}  
 \label{fig:gnutella_query}  
 \end{figure}  
406    
407    
408    

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