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Network-aware P2P file sharing over the wireless mobile networks

Network-aware P2P file sharing over the wireless mobile networks. Chung-Ming Huang, Member, IEEE, Tz-Heng Hsu, and Ming-Fa Hsu IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, VOL. 25, NO. 1, JANUARY 2007 報告 : 羅世豪. Outline. Introduction Network-aware P2P File Sharing Architecture

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Network-aware P2P file sharing over the wireless mobile networks

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  1. Network-aware P2P file sharing over the wireless mobile networks Chung-Ming Huang, Member, IEEE, Tz-Heng Hsu, and Ming-Fa Hsu IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, VOL. 25, NO. 1, JANUARY 2007報告:羅世豪

  2. Outline • Introduction • Network-aware P2P File Sharing Architecture • P2P Network Construction • Resource Discovery Scheme • Performance Analysis • Conclusion

  3. Introduction • Two concerns that affect resource discovery and retrieval for P2P file sharing applications in wireless mobile networks are • Peers’ movements in wireless mobile networks • Peers’ join and leave in a P2P file sharing network.

  4. Introduction • A mobile P2P file sharing system needs to address the above issues. • A network-aware discovery scheme for mobile hosts to find new resource providing peers that share files in their currently resident wireless network. • A resource discover control policy for mobile hosts to obtain fresh status of peers, i.e., peers’ join and leave, in a mobile P2P file sharing network.

  5. Introduction • A novel network-aware P2P file sharing architecture that has • A mobility-aware file discovery control (MAFDC) scheme for • Obtaining fresh status of participant peers • Reducing the number of messages used to discover peers in the mobile wireless networks environment, • A resource provider selection algorithm for • Selecting a new resource provider when mobile peers encounter broken connections in wireless mobile networks.

  6. Network-aware P2P File Sharing Architecture • A peer u is an ordinary host that can join and leave a P2P file sharing network freely at any time. • The peer can search, publish, and retrieve files in the mobile P2P file sharing network. • A super-peer is a selected node that provides functions for peers to locate a specific file.

  7. Network-aware P2P File Sharing Architecture

  8. Network-aware P2P File Sharing Architecture • A new super-peer is created when the first peer joins a network-aware cluster Cl. • The super-peer maintains indexes of the shared files and indexes of peers’ location information in its network-aware cluster Cl. • When a requesting mobile peer u sends a lookup request to its own network cluster super-peer , the super-peer checks whether the desired file Ai is available or not.

  9. Network-aware P2P File Sharing Architecture • If the super-peer finds the desired file Ai, it sends a response message to the requesting mobile peer u. • If no such file can be found in the network-aware cluster Cl, the super-peer forwards the lookup request to its nearby network-aware clusters for finding the desired file Ai.

  10. Network-aware P2P File Sharing Architecture • Each lookup request has a Time To Live (TTL) field which is decremented by one at each queried cluster. • When the value of TTL reaches zero, the lookup request is stop forwarding. • Each lookup request has a 32 byte identifier to uniquely identify it on the proposed P2P network.

  11. Network-aware P2P File Sharing Architecture • When a lookup request is passed through a super-peer • The super-peer records the identifier of the lookup request. • If a super-peer receives a lookup request with the same identifier which it has received before. • The lookup request is ignored and is not forwarded. • By checking the identifiers of lookup requests, the proposed P2P network can • Prevent loops and indefinite propagation in whole network.

  12. P2P Network Construction • In the network construction phase, a bootstrap peer directs new peers joining the network to the appropriate clusters. • To find the corresponding cluster of a peer, the bootstrap peer maintains a cluster routing table. • Each entry in the cluster routing table represents a network-aware cluster for peers to join and leave.

  13. P2P Network Construction • Attributes in the cluster routing table are cluster identify number, the primary and backup network-aware cluster domains for that cluster, and a timer.

  14. P2P Network Construction • At the very beginning (no peer exists yet), the cluster routing table is empty. • When the first peer joins, the bootstrap peer determines its network-aware cluster using the BGP routing tables in nearby routers. • If another peer joins with the same network-aware cluster, the most powerful of the two will become the super-peer of the network-aware cluster.

  15. P2P Network Construction • To join the proposed network-aware P2P file sharing network, a peer u contacts one of the bootstrap peers x. • The bootstrap peer x identifies the most suitable network-aware cluster Clof the joining peer u and replies with a short message. • The message contains the address of the super-peer of the network-aware cluster Cl and its backup peer of the cluster Cl.

  16. P2P Network Construction • The joining peer u sends a join request to the super-peer of the network-aware cluster Cl. • The super-peer of the network-aware cluster Clreturns a list of the other super-peers that are participants of the network-aware P2P network. • Then, the joining peer u establishes a connection with the super-peer .

  17. P2P Network Construction • Over the connection time, the joining peer u sends information about its owned files Ai, ...,Amand its computing capacities to its super-peer . • The computing capacities are specified in terms of three resources: bandwidth, CPU, and storage. • The super-peer updates its index with the new peer u and its data.

  18. P2P Network Construction • A joining peer u may be promoted to a super-peer if it owns more resources than the current super-peer . • After the joining process is finished, the promotion process starts from bottom up. • The super-peer that is responsible for the new peer u compares the new peer’s resources versus its own and each of the backup super-peer’s resources.

  19. P2P Network Construction • Although all resources (bandwidth, CPU, and storage) can be used in the comparison • We use the most important one: offered outbound bandwidth. • Fast CPUs and large disks are abundant nowadays. • A threshold is used in the comparison to prevent frequent change of super-peers.

  20. P2P Network Construction • If the new peer becomes the primary super-peer • It gets the index from the replaced super-peer • Informs • The bootstrap peers • All backup super-peers • Peers in the network-aware cluster. • Two different cases that need to be considered are as follows: • Regular peer leave • Super-peer leave

  21. P2P Network Construction • When a regular peer u leaves the network-aware P2P file sharing network • It sends a leave message to its super-peer , which updates the index to reflect the peer’s leave. • Before leaving, a super-peer • Selects a new primary super-peer from the backup list • Informs it • Updates its indexes • Sends a leave message • To the bootstrap peer x • To the active peers in the network cluster.

  22. P2P Network Construction • The leave message contains the IP address of the new super-peer. • The new super-peer establishes a control connection with its bootstrap peer. • The active peers • Close the connection with the old super-peer • Open new ones with the new super-peer.

  23. Resource Discovery Scheme - Mobility-Aware File Discovery Control Scheme • A mobile peer that requests files can send messages periodically to discover peers and select a new and better one for file retrieval. • Waste network bandwidth if each requesting mobile peer sends a lot of messages periodically to discover peers that share files. • We propose a novel file discovery control scheme named mobility-aware file discovery control (MAFDC) scheme.

  24. Resource Discovery Scheme - Mobility-Aware File Discovery Control Scheme • The MAFDC scheme can • Find new resource providing peers quickly when a new coming file is shared. • Reduce the number of messages that are used to discover new resource providing peers. • In the MAFDC scheme, there are two kinds of query modes for mobile peers to discover new resource providing peers: • Publish-subscribe query mode • Continuous query mode

  25. Resource Discovery Scheme - Mobility-Aware File Discovery Control Scheme: Publish-Subscribe Query Mode • In the MAFDC scheme, when theyjoin the proposed P2P file sharing network mobile peers • Connect with super-peers • Publish shared file lists to the super-peers. • In the publish-subscribequery mode • A requesting mobile peer can registerinterests (queries) to super-peers by sending subscription messages.

  26. Resource Discovery Scheme - Mobility-Aware File Discovery Control Scheme: Publish-Subscribe Query Mode • A subscribe-driven discovery control (SDC) algorithmis proposed to • Reduce the number of messages that are usedto discover resource providing peers in the publish-subscribequery mode. • When a requestingmobile peer u wants to submit an interest of file query q • Peer u connects to a nearby network-aware super-peer .

  27. Resource Discovery Scheme - Mobility-Aware File Discovery Control Scheme: Publish-Subscribe Query Mode • Then peer u sendsa SubscribeFileQuery(id, q, ql) message to super-peer . • id is a unique identifier of peer u • ql is the query lifetime of query q. • A subscribed query entry which has not beenmatched for more than ql seconds will be deleted. • When super-peerreceives query message q • Itinserts the query q in itslocal query table for comparing the incoming shared file lists.

  28. Resource Discovery Scheme - Mobility-Aware File Discovery Control Scheme: Publish-Subscribe Query Mode • Each query message q has a timeout value QueryTimeOut for preventing stale information stored in the query table. • Once a new peer v joins the P2P file sharing network, the peer v • connects a super-peer • sends a message PublishFileResource(id, l) • l is the shared file list of the new joined peer. • When super-peer receives the message • It compares shared file lists for finding the matching query q.

  29. Resource Discovery Scheme - Mobility-Aware File Discovery Control Scheme: Publish-Subscribe Query Mode • Once a matching query has been found from the shared file lists, super-peer sends a notification message FileNotification(id, r) • r is a list containing resource indicators which point to the matching resource providing peers. • In case of a requesting mobile node u moves from network C1to a new visit network C2 • The requesting mobile node u can send a messageRenewQuery(id, q, ip) to the original super-peer .

  30. Resource Discovery Scheme - Mobility-Aware File Discovery Control Scheme: Publish-Subscribe Query Mode • The super-peer will update its query table with the new ip address of the mobile node u. • Once a matching query has been found from the shared file lists • Super-peer sends a notification message to the new ip address of the mobile node u.

  31. Resource Discovery Scheme - Mobility-Aware File Discovery Control Scheme: Continuous Query Mode • In the continuous query mode, a requesting mobile peer u can send discovery messages for finding resource providing peers according to the connection status of the mobile peers. • The receiver-driven discovery control (RDC) algorithm can be adopted to tackle this mode. • The RDC algorithm is used to reduce the number of messages that are used to discover resource providing peers in the continuous query mode.

  32. Resource Discovery Scheme - Mobility-Aware File Discovery Control Scheme: Continuous Query Mode • The RDC algorithm uses a pre-configured threshold RequiredTransRate • Evaluate that a connection is usable or less usable for retrieving a file in wireless mobile networks.

  33. Resource Discovery Scheme - Mobility-Aware File Discovery Control Scheme: Continuous Query Mode • Connection’s transmission rate >= RequiredTransRate • The next time period for sending discovery messages will be extendedin order to reduce the number of messages for finding resource providing peers. • Connection’s transmission rate < RequiredTransRate • The next time period for sending discovery messages will be shrunk in order to find new and better resource providing peers as soon as possible.

  34. Resource Discovery Scheme - Resource Provider Selection • In case of a resource provider v being a fixed node, the performance of file retrieval will be degraded when a requesting mobile nodeu roams among different networks. • The requesting mobile node u can send a new query q to the nearby super-peer when the mobile node u moves from network C1 to a new visit network C2.

  35. Resource Discovery Scheme - Resource Provider Selection • In the proposed scheme, the super-peer will response a message to the requesting mobile peer u. • The responded message contains a list of candidate resource providing peers that are located in current network. • The requesting mobile peer u can select a new resource providing peer w according to the network performance metrics such as bandwidth and round-trip time (RTT) information.

  36. Resource Discovery Scheme - Resource Provider Selection • In case of a resource provider v being a mobile node, the performance of file retrieval will be degraded when a requesting mobile node u or resource providing peer vroams among different networks. • The resource providing peer v can register it’s mobility information with the nearby super-peer when the resource providing peer v moves from network C2 to a new visit network C3.

  37. Resource Discovery Scheme - Resource Provider Selection • Meanwhile, the resource providing peer v needs to • Update its information with super-peer • Send messages to notify those peers who are retrieving files from it. • When a requesting mobile peer u receives the notification • Send a new query to its nearby super-peer for rediscovering a desired file in the currently visited network C2.

  38. Resource Discovery Scheme - Resource Provider Selection • The super-peer will response a message to the requesting mobile peer u. • The responded message contains • A list of candidate resource providers • Theirmobility information.

  39. Resource Discovery Scheme - Resource Provider Selection • The requesting mobile peer u can select a new resource provider according to the mobility information such as • moving speed • network performance metrics • Bandwidth • round-trip time (RTT) information. • The mobility information is an important metric that affect the retrieval performance • The connection with mobile resource provider will be broken unpredictably

  40. Resource Discovery Scheme - Resource Provider Selection • The resource provider selection (RPS) algorithm • Help peers to resume interrupted connection quickly. • The resource provider selection (RPS) algorithm uses • The roundtrip time (RTT) information • Packet loss rate as the cost function c(u, v). • The resource provider selection (RPS) will select the node that has the minimum cost as the current resource-providing peer.

  41. Performance Analysis • 2000 wired nodes in a (10000m * 10000m) grid in the simulated P2P model. • The generated mobile nodes’ mobility patterns • based on the random way-point mobility model. • The mobile node is moving to its destination with a speed uniformly selected from (0 m/s, 2 m/s).

  42. Performance Analysis • Each mobile node is configured with the 802.11b MAC protocol • Transmission range : 250m • Transmission rate : 2Mbits/sec • Mobile nodes retrieve desired files using the FTP protocol. • New peers join the P2P network according to the Poisson distribution.

  43. Performance Analysis • Arrival rates of mobile nodes • 10 nodes/sec • Average number of mobiles nodes per cluster • 100 nodes/cluster • Number of shared files of each node • 10 files/node. • The simulation is the average over 50 independent simulations.

  44. Performance Analysis • Three resource discovery schemes are evaluated in the simulation: • Receiver-driven discovery control (RDC) scheme • Periodical-based discovery control (PDC) scheme • Subscribe-driven discovery control (SDC) scheme

  45. Performance Analysis • A requesting mobile peer retrieves a file from the peer that has the most available bandwidth • In the RDC scheme : by sending query messages according to the proposed RDC algorithm. • In the PDC scheme : by sending query messages periodically. • In the SDC control scheme, a super-peer responses matched query messages to requesting mobile peers in the publish-subscribe mode.

  46. Performance Analysis • Figure 2 shows the influence that the movement of the mobile node causes.

  47. Performance Analysis • The data packet routing path may be changed and the data loss rate may be increased in wireless mobile networks. • The performance of retrieving files in wireless mobile networks is unstable.

  48. Performance Analysis • It shows that the RDC method is better than the SDC method in a wireless mobile network.

  49. Performance Analysis • The SDC method lets a mobile peer subscribe its interest (query) to a super-peer. • When new files are shared/published in the subscribed cluster, the super-peer sends a matched query message to the requesting mobile peer.

  50. Performance Analysis • When new files are shared/published in other clusters, the requesting mobile peer will not be notified because it does not subscribe its interests to these clusters. • This makes the requesting mobile peer not be able to select the best resource providing peers. • Therefore, the average data throughput is not so good as the RDC approach in a wireless mobile network.

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