cs5229 09/10 lecture 9: internet packet dynamics
TRANSCRIPT
![Page 1: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/1.jpg)
1 22 August 2008 NUS CS5229 Semester 1 2008/09
Vern Paxson’s Paper"“End-to-End"
Internet Packet Dynamics”, 1997/99
![Page 2: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/2.jpg)
2 22 August 2008 NUS CS5229 Semester 1 2008/09
How often are packets dropped?"
How often are packets reordered?" :
![Page 3: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/3.jpg)
3 22 August 2008 NUS CS5229 Semester 1 2008/09
Why these questions?
![Page 4: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/4.jpg)
4 22 August 2008 NUS CS5229 Semester 1 2008/09
1. Understand the Internet
![Page 5: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/5.jpg)
5 22 August 2008 NUS CS5229 Semester 1 2008/09
“ ”
when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind;
- Lord Kelvin
![Page 6: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/6.jpg)
6 22 August 2008 NUS CS5229 Semester 1 2008/09
2. Model the Internet
![Page 7: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/7.jpg)
7 22 August 2008 NUS CS5229 Semester 1 2008/09
3. Enable more accurate evaluation through simulations
![Page 8: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/8.jpg)
8 22 August 2008 NUS CS5229 Semester 1 2008/09
4. Lead to a better application/systems
design
![Page 9: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/9.jpg)
9 22 August 2008 NUS CS5229 Semester 1 2008/09
How often are packets dropped?"
How often are packets reordered?" :
![Page 10: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/10.jpg)
10 22 August 2008 NUS CS5229 Semester 1 2008/09
How to answer these questions?
![Page 11: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/11.jpg)
11 22 August 2008 NUS CS5229 Semester 1 2008/09
Collect lots of packet traces"
Analyze the traces
![Page 12: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/12.jpg)
12 22 August 2008 NUS CS5229 Semester 1 2008/09
Trace collection:"
large number of flows"
a variety of sites"
many packets per flow"
use TCP
![Page 13: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/13.jpg)
13 22 August 2008 NUS CS5229 Semester 1 2008/09
Why TCP:"
real-world traffic"
will not overload the network
![Page 14: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/14.jpg)
14 22 August 2008 NUS CS5229 Semester 1 2008/09
Time between measurement is Poisson distributed."
PASTA Theorem: Intuitively, if we make n observations and k observations is in some state S and n-k in other states, then we can assume prob of observing S is approximately k/n.
![Page 15: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/15.jpg)
15 22 August 2008 NUS CS5229 Semester 1 2008/09
Two traces:"
N1: Dec94 "N2: Nov-Dec95"
use tcpdump at sender + receiver"
![Page 16: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/16.jpg)
16 22 August 2008 NUS CS5229 Semester 1 2008/09
100 kB Size of file transfered
![Page 17: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/17.jpg)
17 22 August 2008 NUS CS5229 Semester 1 2008/09
21 Number of sites
![Page 18: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/18.jpg)
18 22 August 2008 NUS CS5229 Semester 1 2008/09
20800 Number of trace pairs
![Page 19: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/19.jpg)
19 22 August 2008 NUS CS5229 Semester 1 2008/09
Part 1:"The Unexpected
![Page 20: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/20.jpg)
20 22 August 2008 NUS CS5229 Semester 1 2008/09
Packet Reordering
![Page 21: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/21.jpg)
21 22 August 2008 NUS CS5229 Semester 1 2008/09
1 2 5 3 4
2 reorderings
![Page 22: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/22.jpg)
22 22 August 2008 NUS CS5229 Semester 1 2008/09
36% 12% N1 N2
Percentage of connections with at least one out-of-order delivery
![Page 23: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/23.jpg)
23 22 August 2008 NUS CS5229 Semester 1 2008/09
2% .3% N1 N2
Percentage of data packets out-of-order
![Page 24: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/24.jpg)
24 22 August 2008 NUS CS5229 Semester 1 2008/09
.6% .1% N1 N2
Percentage of ACK packets out-of-order
![Page 25: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/25.jpg)
25 22 August 2008 NUS CS5229 Semester 1 2008/09
Data packets are usually sent
closer together.
![Page 26: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/26.jpg)
26 22 August 2008 NUS CS5229 Semester 1 2008/09
15% .2% From To
Percentage of packets out-of-order to and from U of Colorado in N1.
![Page 27: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/27.jpg)
27 22 August 2008 NUS CS5229 Semester 1 2008/09
Route fluttering: alternate packets can take different
route to dest.
![Page 28: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/28.jpg)
28 22 August 2008 NUS CS5229 Semester 1 2008/09
Taken from Paxson’s PhD Thesis: Alternate routes are taken for packets from WUSTL to U Mannheim
![Page 29: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/29.jpg)
29 22 August 2008 NUS CS5229 Semester 1 2008/09
Fig 1 from the paper, showing large gap and two slopes.
![Page 30: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/30.jpg)
30 22 August 2008 NUS CS5229 Semester 1 2008/09
Fig 1 from the paper, showing large gap and two slopes.
T1 (new arrival)
Ethernet (buffered packets)
![Page 31: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/31.jpg)
31 22 August 2008 NUS CS5229 Semester 1 2008/09
Impact of Packet Reordering
![Page 32: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/32.jpg)
32 22 August 2008 NUS CS5229 Semester 1 2008/09
Recap: TCP’s fast retransmit
![Page 33: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/33.jpg)
33 22 August 2008 NUS CS5229 Semester 1 2008/09
S = 1000
S = 2000
S = 3000 S = 4000
S = 5000
A = 2000
A = 2000
A = 2000
A = 2000
S = 2000
![Page 34: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/34.jpg)
34 22 August 2008 NUS CS5229 Semester 1 2008/09
S = 1000
S = 2000
S = 3000 S = 4000
S = 5000
A = 2000
A = 2000
A = 2000
A = 2000
S = 2000
![Page 35: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/35.jpg)
35 22 August 2008 NUS CS5229 Semester 1 2008/09
Nd = 3 is a conservative
choice.
![Page 36: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/36.jpg)
36 22 August 2008 NUS CS5229 Semester 1 2008/09
What if receiver wait longer before sending dup ack?
![Page 37: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/37.jpg)
37 22 August 2008 NUS CS5229 Semester 1 2008/09
W
S = 2000
S = 2000
![Page 38: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/38.jpg)
38 22 August 2008 NUS CS5229 Semester 1 2008/09
1 2 5 3 4
Delivery Gap: "time between receiving "an out-of-order packet and "the packet sent before it.
![Page 39: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/39.jpg)
39 22 August 2008 NUS CS5229 Semester 1 2008/09
Taken from Paxson’s PhD Thesis: CDF for delivery gap between reordered packets.
![Page 40: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/40.jpg)
40 22 August 2008 NUS CS5229 Semester 1 2008/09
N2 N1
higher BW
![Page 41: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/41.jpg)
41 22 August 2008 NUS CS5229 Semester 1 2008/09
20ms 8ms N1 N2
Waiting time with which 70% of "out-of-order delivery would be identified.
![Page 42: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/42.jpg)
42 22 August 2008 NUS CS5229 Semester 1 2008/09
Is needless retransmission a
problem?
![Page 43: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/43.jpg)
43 22 August 2008 NUS CS5229 Semester 1 2008/09
Good S = 2000
S = 2000
![Page 44: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/44.jpg)
44 22 August 2008 NUS CS5229 Semester 1 2008/09
S = 2000
S = 2000
Bad
![Page 45: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/45.jpg)
45 22 August 2008 NUS CS5229 Semester 1 2008/09
22 300 N1 N2
Number of good retransmissions for every bad retransmission.
Nd = 3, W = 0
![Page 46: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/46.jpg)
46 22 August 2008 NUS CS5229 Semester 1 2008/09
~7 100 N1 N2
Number of good retransmissions for every bad retransmission.
Nd = 2, W = 0
![Page 47: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/47.jpg)
47 22 August 2008 NUS CS5229 Semester 1 2008/09
15 300 N1 N2
Number of good retransmissions for every bad retransmission.
Nd = 2, W = 20ms
![Page 48: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/48.jpg)
48 22 August 2008 NUS CS5229 Semester 1 2008/09
Packet Corruption
![Page 49: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/49.jpg)
49 22 August 2008 NUS CS5229 Semester 1 2008/09
1 in 5000 packet is corrupted
![Page 50: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/50.jpg)
50 22 August 2008 NUS CS5229 Semester 1 2008/09
1 in 65536 corrupted packet goes undetected
using TCP checksum (assuming each possible checksum is equally likely)
![Page 51: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/51.jpg)
51 22 August 2008 NUS CS5229 Semester 1 2008/09
1 in 300million Internet packet is corrupted "
and is undetected.
![Page 52: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/52.jpg)
52 22 August 2008 NUS CS5229 Semester 1 2008/09
Part 2:"Bottleneck Bandwidth
![Page 53: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/53.jpg)
53 22 August 2008 NUS CS5229 Semester 1 2008/09
Packet Pair
![Page 54: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/54.jpg)
54 22 August 2008 NUS CS5229 Semester 1 2008/09
B bps
b bytes
![Page 55: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/55.jpg)
55 22 August 2008 NUS CS5229 Semester 1 2008/09
Q s
Q x B = b
![Page 56: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/56.jpg)
56 22 August 2008 NUS CS5229 Semester 1 2008/09
Q s
![Page 57: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/57.jpg)
57 22 August 2008 NUS CS5229 Semester 1 2008/09
Q s
![Page 58: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/58.jpg)
58 22 August 2008 NUS CS5229 Semester 1 2008/09
Q s
![Page 59: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/59.jpg)
59 22 August 2008 NUS CS5229 Semester 1 2008/09
Problems with Packet Pair
![Page 60: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/60.jpg)
60 22 August 2008 NUS CS5229 Semester 1 2008/09
1. Asymmetric Link
![Page 61: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/61.jpg)
61 22 August 2008 NUS CS5229 Semester 1 2008/09
![Page 62: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/62.jpg)
62 22 August 2008 NUS CS5229 Semester 1 2008/09
2. ACK Compression
![Page 63: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/63.jpg)
63 22 August 2008 NUS CS5229 Semester 1 2008/09
![Page 64: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/64.jpg)
64 22 August 2008 NUS CS5229 Semester 1 2008/09
3. Out of order delivery
![Page 65: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/65.jpg)
65 22 August 2008 NUS CS5229 Semester 1 2008/09
![Page 66: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/66.jpg)
66 22 August 2008 NUS CS5229 Semester 1 2008/09
4. Clock resolution
![Page 67: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/67.jpg)
67 22 August 2008 NUS CS5229 Semester 1 2008/09
Suppose
B = 1000 kBps b = 1 kB Q = ?
![Page 68: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/68.jpg)
68 22 August 2008 NUS CS5229 Semester 1 2008/09
5. Changing bottleneck bandwidth
![Page 69: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/69.jpg)
69 22 August 2008 NUS CS5229 Semester 1 2008/09
Fig 2 from the paper, showing changing bandwidth.
![Page 70: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/70.jpg)
70 22 August 2008 NUS CS5229 Semester 1 2008/09
Fig 3 from the paper, showing multi-channel links.
![Page 71: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/71.jpg)
71 22 August 2008 NUS CS5229 Semester 1 2008/09
6. Multi-channel Links
![Page 72: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/72.jpg)
72 22 August 2008 NUS CS5229 Semester 1 2008/09
Asymmetric links"ACK compression"Out-of-order delivery"Clock resolution"Changes in bottleneck bandwidth"Multi-channel links"
![Page 73: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/73.jpg)
73 22 August 2008 NUS CS5229 Semester 1 2008/09
Measure at receiver: "Asymmetric links"ACK compression"
Packet bunch:"Out-of-order delivery"Clock resolution"Changes in bottleneck bandwidth"Multi-channel links
![Page 74: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/74.jpg)
74 22 August 2008 NUS CS5229 Semester 1 2008/09
2Q
![Page 75: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/75.jpg)
75 22 August 2008 NUS CS5229 Semester 1 2008/09
Collect multiple estimates, take the most freq occurrence (modes) as the bottleneck bandwidth.
![Page 76: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/76.jpg)
76 22 August 2008 NUS CS5229 Semester 1 2008/09
![Page 77: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/77.jpg)
77 22 August 2008 NUS CS5229 Semester 1 2008/09
Part 3:"Packet Loss
![Page 78: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/78.jpg)
78 22 August 2008 NUS CS5229 Semester 1 2008/09
2.7% 5.2% N1 N2
Percentage of packets that were lost.
![Page 79: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/79.jpg)
79 22 August 2008 NUS CS5229 Semester 1 2008/09
50% 50% N1 N2
Percentage of loss free connections
![Page 80: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/80.jpg)
80 22 August 2008 NUS CS5229 Semester 1 2008/09
5.7% 9.2% N1 N2
Loss rate on lossy connections
![Page 81: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/81.jpg)
81 22 August 2008 NUS CS5229 Semester 1 2008/09
17% Loss rate on connections from EU to US
![Page 82: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/82.jpg)
82 22 August 2008 NUS CS5229 Semester 1 2008/09
Are packet losses independent?
![Page 83: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/83.jpg)
83 22 August 2008 NUS CS5229 Semester 1 2008/09
Compute:"Pu = Pr [ p lost ]"Pc = Pr [ p lost | prev pkt lost ]
![Page 84: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/84.jpg)
84 22 August 2008 NUS CS5229 Semester 1 2008/09
2.8% 49% Pu Pc
Loss rate for “queued data pkt” on N1
![Page 85: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/85.jpg)
85 22 August 2008 NUS CS5229 Semester 1 2008/09
Fig 6 from the paper, showing outage duration.
![Page 86: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/86.jpg)
86 22 August 2008 NUS CS5229 Semester 1 2008/09
Are retransmission
redundant?
![Page 87: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/87.jpg)
87 22 August 2008 NUS CS5229 Semester 1 2008/09
Unavoidable
ACK X
![Page 88: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/88.jpg)
88 22 August 2008 NUS CS5229 Semester 1 2008/09
Coarse Feedback
![Page 89: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/89.jpg)
89 22 August 2008 NUS CS5229 Semester 1 2008/09
Bad RTO
![Page 90: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/90.jpg)
90 22 August 2008 NUS CS5229 Semester 1 2008/09
26% 28% N1 N2
Percentage of retransmissions that"are redundant
![Page 91: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/91.jpg)
91 22 August 2008 NUS CS5229 Semester 1 2008/09
44
51
4
Unavoidable
Coarse Feedback
Bad RTO
Type of redundant retransmission in N1.
![Page 92: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/92.jpg)
92 22 August 2008 NUS CS5229 Semester 1 2008/09
Part 4:"Packet Delay
![Page 93: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/93.jpg)
93 22 August 2008 NUS CS5229 Semester 1 2008/09
OTT is not well approximated using RTT/2
![Page 94: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/94.jpg)
94 22 August 2008 NUS CS5229 Semester 1 2008/09
ACK Compression
![Page 95: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/95.jpg)
95 22 August 2008 NUS CS5229 Semester 1 2008/09
(might affect TCP self-clocking)
![Page 96: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/96.jpg)
96 22 August 2008 NUS CS5229 Semester 1 2008/09
sent
recv
![Page 97: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/97.jpg)
97 22 August 2008 NUS CS5229 Semester 1 2008/09
Sending interval
Receiving interval
![Page 98: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/98.jpg)
98 22 August 2008 NUS CS5229 Semester 1 2008/09
![Page 99: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/99.jpg)
99 22 August 2008 NUS CS5229 Semester 1 2008/09
![Page 100: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/100.jpg)
100 22 August 2008 NUS CS5229 Semester 1 2008/09
Compression event if ξ < .75
![Page 101: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/101.jpg)
101 22 August 2008 NUS CS5229 Semester 1 2008/09
50% 60% N1 N2
Percentage of connection that experiences"at least one compression event.
![Page 102: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/102.jpg)
102 22 August 2008 NUS CS5229 Semester 1 2008/09
50% 60% N1 N2
Percentage of connection that experiences"at least one compression event.
![Page 103: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/103.jpg)
103 22 August 2008 NUS CS5229 Semester 1 2008/09
2 Average number of events per connection.
![Page 104: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/104.jpg)
104 22 August 2008 NUS CS5229 Semester 1 2008/09
Estimating Available
Bandwidth
![Page 105: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/105.jpg)
105 22 August 2008 NUS CS5229 Semester 1 2008/09
Qb: time to transit the bottleneck"
ψi: expected time spent queuing behind predecessor (derived from sending time)"
γi: diff between packet OTT and min OTT
![Page 106: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/106.jpg)
106 22 August 2008 NUS CS5229 Semester 1 2008/09
time packet i is sent
![Page 107: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/107.jpg)
107 22 August 2008 NUS CS5229 Semester 1 2008/09
![Page 108: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/108.jpg)
108 22 August 2008 NUS CS5229 Semester 1 2008/09
β = 1 means all bandwidth is available."
β = 0 means none of the bandwidth is available.
![Page 109: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/109.jpg)
109 22 August 2008 NUS CS5229 Semester 1 2008/09
Fig 10 from the paper, showing distribution of available bandwidth.
![Page 110: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/110.jpg)
110 22 August 2008 NUS CS5229 Semester 1 2008/09
Conclusion
![Page 111: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/111.jpg)
111 22 August 2008 NUS CS5229 Semester 1 2008/09
The numbers in the paper are not important. "
(the Internet has changed)
![Page 112: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/112.jpg)
112 22 August 2008 NUS CS5229 Semester 1 2008/09
Measurement is difficult but useful
![Page 113: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/113.jpg)
113 22 August 2008 NUS CS5229 Semester 1 2008/09
Many new techniques needed (e.g to
measure bottleneck bandwidth)
![Page 114: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/114.jpg)
114 22 August 2008 NUS CS5229 Semester 1 2008/09
We can improve current design (e.g.
TCP if we know more about reordering)
![Page 115: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/115.jpg)
115 22 August 2008 NUS CS5229 Semester 1 2008/09
We can identify problem (e.g. packet
corruption)
![Page 116: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/116.jpg)
116 22 August 2008 NUS CS5229 Semester 1 2008/09
We can better model the behavior (e.g.
bursty packet loss)
![Page 117: CS5229 09/10 Lecture 9: Internet Packet Dynamics](https://reader034.vdocuments.mx/reader034/viewer/2022042614/5580406dd8b42ae32c8b4594/html5/thumbnails/117.jpg)
117 22 August 2008 NUS CS5229 Semester 1 2008/09
We can infer much info from just a
packet trace (e.g. available bandwidth)