PGM: experminents with the IF toolset Marc Boyer LIAFA - Univ. - - PowerPoint PPT Presentation

PGM: experminents with the IF toolset

Marc Boyer LIAFA - Univ. Paris 7 - France

PGM: experminents with the IF toolset – p.1/21

The protocol

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PGM

PGM = Pragmatic General Multicast Pragmatic = basic reliability, no membership Multicast = diffusion trough a tree NAK-oriented

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Ideal behavior

Sender Node Receiver Application ODATA(1) ODATA(1) ODATA(1) ODATA(2) ODATA(3) ODATA(4) ODATA(2) ODATA(3) ODATA(4) ODATA(2) ODATA(3) ODATA(4)

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How lost are recovered

Sender Node Receiver Application ODATA(1) ODATA(1) ODATA(1) ODATA(2) ODATA(3) ODATA(3) NAK(2) 2 3 NAK(2) NCF(2) ODATA(3) ODATA(2) NCF(2) RDATA(2) RDATA(2)

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If the NAK is “too late”

1 1 2 3 3 2 4 3 4 Sender Node Receiver Application ODATA(1) ODATA(1) ODATA(3) ODATA(3) ODATA(2) ODATA(1) 1 2 2 3 2 3 4 3 4 5 ODATA(4) ODATA(5) 2 5

???

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Loss unrecoverable

1 1 2 3 3 2 4 3 4 Sender Node Receiver Application ODATA(1) 1 2 2 3 2 3 4 3 4 5 2 5 ODATA(1,1) ODATA(2,1) ODATA(3,1) ODATA(4,2) ODATA(1,1) ODATA(3,1) ODATA(5,3) LOSS(2) ODATA(3) ODATA(4) ODATA(5)

+ SPM messages

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First experiment: untimed model

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Basic property

Are all messages delivered or declared as lost ? topology S-N-R FIFO channels

• nly ODATA can be lost

SPM rate linked to the advance of the window

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Last window

The last window can be “frozen”

Sender Node Receiver Application ODATA(1) 7 8 9 6 7 8 5 6 7 4 5 6 ODATA(6,4) ODATA(6,4) ODATA(7,5) ODATA(8,6) ODATA(9,7) ODATA(8,6) 7 8 7 8 9 Waiting...

add of a “closing SPM”

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Closing SPM

Sender Node Receiver Application ODATA(1) 7 8 9 6 7 8 5 6 7 4 5 6 ODATA(6,4) ODATA(6,4) ODATA(7,5) ODATA(8,6) ODATA(9,7) ODATA(8,6) 7 8 7 8 9 SPM(9,10) LOSS(7) ODATA(8) ODATA(9)

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Topology reduction

Can we remove the nodes? Are both systems equivalent?

Sender Node Receiver

• Receiver

Sender

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Equivalence point of view

as a black box from the sender point of view from the receiver point of view

Receiver Sender Receiver Sender Sender Receiver PGM: experminents with the IF toolset – p.13/21

Equivalence Result

No equivalence for the receiver... Tuning the hiding relation: hiding the NCF hiding all but NCF and NAK

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Second experiment: timed model

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The model

topology S-N-R FIFO channels with delays

• nly ODATA can be lost

SPM rate linked to the advance of the window

Sender Node Receiver

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Recovering a loss

∆

ODATA/SPM NAK RTT

Did the NAK arrives “in time”?

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Duration

• ✁

LOSS_MAX

PROD_RATE

Window Size

Mess seq. num.

AMB_RATE

PROD_RATE Note:

false for the last messages (

LOSS_MAX

Window Size

)

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Lifetime of messages in transmit window

nothing specified in the RFC a sender can drop each message once send

• ur model:

try to keep the max. numb. of packets constant rate fom producer

• ✁

Window Size

PROD_RATE

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Experiments

Recovering all losses, except first and last window:

Window Size

• ✁
• ✂

LOSS_MAX

AMB_RATE

PROD_RATE (1)

see ProdRateVsLosses.pdf see WindowVsLosses.pdf see AmbRateVsLosses.pdf

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Conclusion

work under progress trying to generate the relation with TReX

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