Outline

1. MCDP-LAN: an efficient Multimedia Content Distribution Protocol over LANByFrancesc BurrullFrancisco Miguel Monzo-SanchezFernando CerdanJoan Garcia-HaroJosemaria Malgosa SanahujaInformation and Communication Technologies DepartmentUPCT-Spain

2. Outline • Scenario • Motivation and equipment • Problems • Weakness of the Client-Server model • Intense Multimedia contents demand • Proposed solution: MCDP-LAN • Main features • Typical MCDP-LAN situation • MCDP-LAN core • Summary, Conclusions and Future Work

3. Scenario Motivation • Low cost system built with mass deployed technology • Need to guarantee robustness in a commercial environment

4. Scenario Equipment • Collection of POS (Point of Sales terminals) interconnected with an Ethernet hub

5. Scenario Equipment • POS options: • Bar-code reader • Touch sensitive screen • Photo printer • Bill reader

6. Problems Weakness of the Client-Server model • If a server malfunction occurs the whole system goes down 1 POS 2 POS i POS POS POS N-1 N Server Multimedia content

7. Problems Intense Multimedia content demand • If an intense demand occurs (typical) server collapses POS 1 2 POS i POS POS POS N-1 N Server Multimedia content

8. Proposed solution: MCDP-LAN Main features • Broadcast communications • Traffic in the LAN independent of the product demand • Traffic independent of the number of POS • Traffic only depends on content appearance in the LAN Multimedia content 1 POS 2 POS i POS POS POS N-1 N

9. Proposed solution: MCDP-LAN Typical MCDP-LAN situation (I) • All of the POS operating normally content α 1 POS 2 POS i POS POS POS N-1 N A • New content arrival starts content broadcast α α α α α POS 2 POS i POS POS POS N-1 N B

10. Proposed solution: MCDP-LAN Typical MCDP-LAN situation (II) content β • Malfunction of the POS i α α α α α 1 POS 2 POS i POS POS POS N-1 N C • After content broadcast: α, β α, β α α, β α, β POS 2 POS i POS POS POS N-1 N D

11. Proposed solution: MCDP-LAN Typical MCDP-LAN situation (III) content γ • (re)appearance of the POS i α, β α, β α α, β α, β 1 POS 2 POS i POS POS POS N-1 N E • After content broadcast: α, β, γ α, β, γ α, γ α, β, γ α, β, γ POS 2 POS i POS POS POS N-1 N F

12. Proposed solution: MCDP-LAN Typical MCDP-LAN situation (IV) • Worst case: user in POS i demands content β β α, β, γ α, β, γ α, γ α, β, γ α, β, γ POS 2 POS i POS POS POS N-1 N G • A broadcast of the content β has to be repeated from any of the POS that has this content: Performance degradation

13. Proposed solution: MCDP-LAN MCDP-LAN core • Broadcast -normal operation- • POS i starts a broadcast -packet 1- • POS i receives x acknowledges (1<=x<=N), adds them to a list and timeout of packet 1 expires • POS i continues packet 2 broadcast, waiting for all the acknowledgements in the list to broadcast packet 3, and so on.

14. Proposed solution: MCDP-LAN MCDP-LAN core • Broadcast -special cases- • If an expected acknowledgement is missed, then when timeout expires the responsible POS is eliminated from the list • If a new unexpected acknowledgement appears the responsible POS is added to the list • If a negative acknowledge occurs the list is cleared and the broadcast algorithm restarts from the requested packet.

15. Proposed solution: MCDP-LAN MCDP-LAN core • Reception • Normal operation consists of sending an acknowledgement for every received packet • If an unexpected packet is received, it is discarded and a negative acknowledgement is sent • If negative acknowledgements are sent often the POS stops the reception of the content (favouring the rest)

16. Summary Conclusions and Future Work • The response time using MCDP-LAN model is shorter than using the traditional Client-Server model • The required robustness of the system using MCDP-LAN is not compromised by Client-Server networking issues • Future work: Adapting the system to a mobile environment

17. MCDP-LAN: an efficient Multimedia Content Distribution Protocol over LANByFrancesc BurrullFrancisco Miguel Monzo-SanchezFernando CerdanJoan Garcia-HaroJosemaria Malgosa SanahujaInformation and Communication Technologies DepartmentUPCT-Spain