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Supporting Legacy Applications in Associative Overlay Networks

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  1. Supporting Legacy Applications in Associative Overlay Networks Shelley Zhuang, Ion Stoica {shelleyz, istoica}@CS.Berkeley.EDU Sahara Retreat January 16-18, 2002 http://www.cs.berkeley.edu/~shelleyz/research/aon

  2. (ID, data) (ID, data) (ID, R) Associative Overlay Networks • Implements rendezvous-based communication abstraction • Overlay network which consists of a set of servers that store triggers and forwards packets between end-points Receiver (R) Sender

  3. 5 8 9 (IDS, S) 6 7 (IDC, C) 1 2 4 3 (IDP, S) AON Native Application • Two types of triggers:  public and private • Server maintains a public trigger, IDP • Client creates a private trigger identifier IDC • Server creates a private trigger identifier IDS • Client and server insert the private triggers (IDC, IPC) and (IDS, IPS) Client (C) Server (S)

  4. Legacy Applications • Design goals • User should be able to choose between an AON-aware application or regular application • Should not require changes to existing infrastructure such as IP network routers, DNS • Proposed solution • Configure existing applications to connect to a local AON proxy that translates and forwards packets transparently over AON • Run an AON proxy locally

  5. Transparent Application Support • Example: telnet client-server application • TCP connection established via proxies: • Client (C)  Client Proxy (CP)  AON  Server Proxy (SP)  Server (S) • Private trigger identifiers (IDC, IDS) exchanged in 3-way handshake • Packets forwarded via proxies • Proxies rewrite TCP packets


  6. Control Path Operations • Server, S, runs telnet server • Server Proxy, SP • IDP = Hash1(telnet.S.aon.net) • Inserts trigger (IDP, IPSP /PSP) into AON • Inserts trigger (IDS, IPSP /PSP) into AON • Client, C, runs wrapper script “aon_telnet S” • IDP = Hash1(telnet.S.aon.net) • Send SETUP(IDP) to CP • CP sends back ACCEPT(P’CP = Hash2 (telnet.S.aon.net)) • Telnet 127.0.0.1 P’CP • Client Proxy, CP • Inserts trigger (IDC, IPCP /PCP) into AON

  7. Pros and Cons • Advantages • Client can make multiple connections to the same service on S simultaneously • Client can use more than one service on S simultaneously • Client can use the same service on two different servers simultaneously • No changes to existing infrastructure • Limitations • Per-application script • Not as general as solutions based on LD_PRELOAD, LD_LIBRARY, or system call trapping

  8. Discussion • End-to-end host mobility • Without changes to IP layer (Mobile IP) • Without changes to TCP protocol (MIGRATE) • Supports sender and receiver mobility • Server load balancing • Nearby server selection

  9. TCP Three-Way Handshake

  10. Translation Table • Client Proxy • IPCP /P’CP IDP • IDC  IPC /P’C • IDC  IPC P/P’CP • IPC /P’C  IDS • Server Proxy • IDP  IPS /PS • IDS  IPS /PS • IDS  IPSP /P’SP • IPSP /P’SP IDC

  11. Data Path Operations