l5 Congestion Control

l5 Congestion Control - Lecture 5: Congestion Control...

Info iconThis preview shows pages 1–12. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Lecture 5: Congestion Control Overview Internet is a network of networks Narrow waist of IP: unreliable, best-effort datagram delivery Packet forwarding: input port to output port Routing protocols: computing port mappings Transport: end-to-end, reliability, flow control, and congestion control Transport Provides end-to-end communication between applications UDP: unreliable datagram delivery (thin layer on top of IP) TCP: reliable stream delivery TCP Connection establishment Connection teardown Retransmission timeout (RTT and variance) Flow control (receiver window) Congestion control (transmit window) TCP Connection establishment Connection teardown Retransmission timeout (RTT and variance) Flow control (receiver window) Congestion control (transmit window) A Bit of History 1974: 3-way handshake 1978: TCP and IP split into TCP/IP 1983: January 1, ARPAnet switches to TCP/IP 1986: Internet begins to suffer congestion collapses 1987-8: Van Jacobson fixes TCP, publishes seminal paper (Tahoe) 1990: Fast recovery and fast retransmit added (Reno) Three questions Goal: maintain TCP goodput at equilibrium When does TCP retransmit packets? When does TCP transmit packets? When does TCP ack packets? Flow Control Part of TCP specification (pre-1988) Want to make sure we dont send more than what the receiver can handle Sliding window protocol as described in lecture 3 Use window header field to tell other side how much space you have Rule: Sent and unacknowledged bytes window TCP segment 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1 2 3 source port destination port sequence number acknowledgment number reserved U R data G A P R S F C K S H S T Y N I N Window data offset checksum urgent pointer options padding Send Timing Before Tahoe- On connection, nodes send full window of packets- Retransmit packet immediately after its timer expires Result: window-sized bursts of packets in network Bursts of packets Retransmission...
View Full Document

This note was uploaded on 04/02/2012 for the course CS 144 at Stanford.

Page1 / 46

l5 Congestion Control - Lecture 5: Congestion Control...

This preview shows document pages 1 - 12. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online