Έλεγχος Συμφόρησης TCP
of 13
/13
Embed Size (px)
description
Έλεγχος Συμφόρησης TCP. Δίκτυα Υπολογιστών Χειμερινό Εξάμηνο 2008-2009. Μαρία Κουτσογιαννάκη. Λόγοι συμφόρησης. Ο Host A στέλνει στο δίκτυο δεδομένα με μέσο ρυθμό λ in = # bytes/sec O Host B στέλνει στο δίκτυο δεδομένα με μέσο ρυθμό λ in = # bytes/sec - PowerPoint PPT Presentation
Transcript of Έλεγχος Συμφόρησης TCP
-
TCP 2008-2009
-
Host A in = #bytes/sec O Host B in = #bytes/sec O Router C
-
buffer ( retransmissions) in . . out
TCP in = out B, router C/2
-
Host in C/2 in out buffer router -- Host A:
-
buffer , buffer TCP congested router
!
- TCP TCP LastByteSent - LastByteAcked
- (1/2) ssthreshCongWin = Maximum Segment Size (maximum IP datagram size) Threshold ssthresh
-
(2/2)
-
TCP (latency) L: TCP 2 RTT + O/R
-
TCP ACK segment
-
TCP ACK 2 RTT + O/R
* (O/W ) - 1Latency = 2 RTT + O/R + (K-1)[S/R + RTT - W S/R]
-
TCP
-
James Kurose, Keith Ross 287 26 288 31
2RTT+o/R+S/R+RTT-2S/R =3RTT+O/R-S/R gia W=2 kai K= 4/2-1 = 1; *Gia w=1 kai O = 2S k = 2 2RTT+O/R +S/R+RTT WS/R = 2RTT+O/R+RTT-S/RGia w=2 kai O =4S k=2 2RTT+O/R +S/R+RTT WS/R = 2RTT+O/R+RTT-2S/R Gia w=4 kai O = 8S k =2 2RTT+O/R +S/R+RTT WS/R = 2RTT+O/R+RTT-4S/R *
