Data and Computer Communications

Chapter 18 – Internet Protocols

Data and Computer Communications

Chapter 19 – Internetwork Operation

Data and Computer Communications

Chapter 20 – Transport Protocols

Retransmission Timer Management

1K

1i

)i(RTT1K

1)1K(ARTTSimple averaging method

)1K(RTT1K

1)K(ARTT

1K

K)1K(ARTT

Exponential average

)1K(RTT1)K(SRTT)1K(SRTT Smoothed round-trip time estimate

Retransmission timeout

constanta is ,)K(SRTT)1K(RTO

RTT variance estimation (Jacobson’s algorithm))1K(RTTg)K(SRTT)g1()1K(SRTT

)K(SRTT)1K(RTT)1K(SERR

)1K(SERRh)K(SDEV)h1()1K(SDEV

)1K(SDEVf)1K(SRTT)1K(RTO