CSC358Tutorial6ShuhaoLiu(TA)Feb29,2016

Agenda

• Problem1,Assignment3Discussion

• TutorialProblem1:Stop-and-waitARQ

• TutorialProblem2:Alternating-bitProtocol

• TutorialProblem3:TransportProtocolDesign

A3-1:Go-back-N

A3-1:Go-back-N

A3-1:Go-back-N

A3-1:Go-back-N

A3-1:SelectiveRepeat

A3-1:SelectiveRepeat

A3-1:SelectiveRepeat

Tut6:P1solution

Tut6:P2solution

• Binary-codedsequencenumber

• Cannotdifferentiatethe1st,3rd,5th…message

• Workswellifnoout-of-orderpackets

Tut6:P3Notes

• Aà B(request)lossy• Bà A(dataresponse)lossless• Delay:unknown&variable

• AslongasBgetstherequest,Awillreceivethecorrespondingdataresponseeventually.• Wedon’tknowiffeedbackmechanismworks…

Tut6:P3Solution

• Ahastoblindlyresendtherequestifthereplyisnotreceived.• Duplicatedrequestsmightbegenerated.• Bmightreceiveduplicatedrequests,thenAmightreceiveduplicateddata.• Weneedasequencenumber(1bit).

Tut6:P3Solution

Tut6:P3Solution