L26_reliable_transport_designing_large_networks

L26_reliable_transport_designing_large_networks - Reliable...

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Reliable Transport & Designing Large Networks Lecture 26 6.02 Fall 2008 May 12, 2008 Sliding window protocol “Stateless” routers Topological addressing Reliable Data Transport Story Thus Far • Basic mechanism • Sender uses sequence numbers • Receivers send ACKs on packet reception • Sender estimates RTT and RTT deviation dynamically to compute timeout (RTO) • Retransmit on timeout • Stop-and-wait protocol: simple, but poor performance (1 packet/RTT) • Fixed window to improve performance
Background image of page 1

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

View Full Document Right Arrow Icon
2 At Least Once Protocol: Take 2 Fixed Window • Receiver tells the sender a window size • Sender sends window • Receiver acks each packet as before • Window advances when all previous packets in window are acked • E.g., 5-7 sent after 2-4 ack’d • Timeout rxmit pkt • Problem w/ fixed window protocol? Host A Host B Send? OK, 3 pkts Idle 2-4 5-7 At Least Once Protocol: Take 3 Fixed-Size Sliding Window • Senders advances the window by 1 for each in- sequence ack it receives • I.e., window slides • So, idle period reduces • Pipelining idea! • But what’s the correct value for the window? • We’ll revisit this question • First, we need to understand windows Host A Host B Idle 3-5
Background image of page 2
3 Sndr Rcvr window = 1-5 p1 a1 6 Sliding Window in Action window = 2-6 a2 p3 Sndr Rcvr 1 2 3 4 5 p1 a1 6 a3 p3 Sliding Window in Action window = 3-7 a2 p3 7 window = 2-6
Background image of page 3

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

View Full Document Right Arrow Icon
4 Sndr Rcvr window = 1-5 p1 a1 x 6 a3 p3 Handling Packet Loss – Alternative 1 window = 2-6 Window definition 1: If window is W, then (last transmitted sequence – last in-order ack) !
Background image of page 4
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

Page1 / 13

L26_reliable_transport_designing_large_networks - Reliable...

This preview shows document pages 1 - 5. Sign up to view the full document.

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