Performance Considerations The window size can be controlled by receiving application Can change the socket buffer size from a default(e.g 8-64Kbytes) to some maximum value Modern TCPs(linux, bsd, os x) may auto-tune Historical source of performance problems on fast nets The window size field in the tcp header limits the window that the receiver can advertise 16 bits >64 KBytes 10 msec rtt>51 Mbit/second 100 msec rtt>5 Mbit/second TCP options to get around 64B limit >increases above limit ecture 17: TCP& Congestion Control
11 Lecture 17: TCP & Congestion Control Performance Considerations • The window size can be controlled by receiving application • Can change the socket buffer size from a default (e.g. 8-64Kbytes) to some maximum value • Modern TCPs (linux, bsd, os x) may auto-tune • Historical source of performance problems on fast nets • The window size field in the TCP header limits the window that the receiver can advertise • 16 bits → 64 KBytes • 10 msec RTT → 51 Mbit/second • 100 msec RTT → 5 Mbit/second • TCP options to get around 64KB limit → increases above limit
Outline TCP flow control Congestion sources and collapse Congestion control basics Lecture 17: TCP Congestion Control
12 Lecture 17: TCP & Congestion Control Outline • TCP flow control • Congestion sources and collapse • Congestion control basics
nternet Pipes? How should you control the faucet? Lecture 17: TCP Congestion Control
13 Lecture 17: TCP & Congestion Control Internet Pipes? • How should you control the faucet?
nternet Pipes? How should you control the faucet? Too fast-sink overflows! Lecture 17: TCP Congestion Control 14
14 Lecture 17: TCP & Congestion Control Internet Pipes? • How should you control the faucet? • Too fast – sink overflows!