Advanced Computer Networks: Lecture 32. This lecture will cover the following: TCP flow control issues; TCP bit allocation limitations; protection against wrap around; adaptive retransmission algorithm; Karn/Partridge algorithm; Jacobson/Karels algorithm;...
CS716 Advanced Computer Networks By Dr. Amir Qayyum Lecture No. 32 TCP Flow Control Issues • Problem: app. delivers tiny pieces of data to TCP – e.g. telnet in character mode – Each piece sent as segment, returned as ACK – Very inefficient • Solutions – Delay transmission to accumulate more data – Nagle’s algorithm • Send first piece • Accumulate data until first piece ACK’d • Send accumulated data and restart accumulation • Not ideal for some traffic, e.g. mouse motion TCP Flow Control Issues • Problem: slow application reads data in tiny pieces – Receiveradvertisestinywindow Senderfillstinywindow Knownassillywindowsyndrome ã Solution:duetoClark AdvertisewindowopeningonlywhenMSSorẵofbufferis available SenderdelayssendinguntilwindowisMSSorẵofreceivers buffer(estimated) OverriddenbyusingPUSH TCPFlowControlMath ã Send buffer size: MaxSendBuffer • Receive buffer size: MaxRcvBuffer • Receiving side – LastByteRcvd LastByteRead