Internet Measurement Tutorial

Internet Measurement Tutorial

Yuval Shavitt

School of Electrical Engineering

http://www.eng.tau.ac.il/~shavitt

Motivation

• Wide area networks are too complex to grasp– Many protocols at various levels interact and

effect behavior

• Many applications have performance requirements– End-to-end delay and loss, reliability

Motivation (2)

• Its an interesting complex system– Has emergent characteristics like many living

systems:• Biological systems

• Social networks

TCP/IP Protocols

TELNET FTP SMTP DNS

TCP UDP

IP

LAN wireless WAN

Application

Transport

Network

Physical+Data link

Internet Measurement Challenges

Internet Measurement Challenges (1)

• Network size:– 100,000,000s hosts, 1,000,000s routers, ~30,000 ASes

• Network Complexity– Interaction between components, protocols,

applications, users

• All change over time– New applications are added

– New protocol versions (TCP)

– New router design (AQM)

Internet Measurement Challenges (2)

• Not engineered for measurement:– Initial design had no measurement thinking– Distributed management

• Tendency not to share data

• Blocking measurement attempts (“don’t ping my network”)

– NATs, Firewalls, …

Success Stories

“On the self-similar nature of Ethernet traffic”W. E. Leland, M. S. Taqqu, W. Willinger, and D. V. Wilson IEEE/ACM Transactions on Networking, February 1994.• Thorough analysis of Bellcore LAN traces established

self-similar properties of packet arrival process.“On power-law relationships of the internet topology”M. Faloutsos, P. Faloutsos, and C. Faloutsos, ACM SIGCOMM 1999, Aug./Sept. 1999.• Analysis of the RouteViews BGP database establish the

power-law characteristics of the Internet topology.

k

Pr(k)

<k>

0 2 4 6 8 10 120

2

4

6

8

10

12

14

log(degree)

log

(Pr(

de

gre

e))

DIMES+BGP (Feb 05)

Why do we measure the Internet?

• Already mentioned:– Because it is there!– Operational reasons

• We cannot improve the Internet if we don’t understand it– We cannot understand it if we don’t measure– We cannot build effective models or simulators

if we don’t measure

Long term objectives

• Monitor the Internet at real time

• Manage the Internet– Monitor and react before things go bad

What can we measure in the Internet?

• Structure– Topology (router/network) connectivity, link

capacities, link loss, available bandwidth, routing• Traffic

– End-to-end performance, packet arrival process (congestion built-up)

• Users and applications– WWW, peer-to-peer, streaming

• Malicious behavior– Attack patterns, port scans

Where can we measure the Internet?

How to chose representative measurement points?

Example: traffic samples– LAN traffic vs. WAN traffic, – Inside an ISP vs. between continents– Country biases– Commercial location vs. educational– More locations is better

How can we measure the Internet?

• Active measurements– Probes: Traceroute, ping, packet trains– Application simulation

• Passive measurement– Logs (WWW)– Monitors, sniffers

Measurement resources on the WWW

CAIDA:

www.caida.org/tools/taxonomy

SLAC: www.slac.stanford.edu/xorg/nmtf/nmtf-tools.html

When should we measure the Internet?

• Diurnal and weekly traffic cycles• Time scales depend on “what” and “how”• Passive measurement are typically continuous

– Can generate huge data sets– Log access problems– Privacy concerns

• Active measurements are typically discrete– Important characteristics can be missed– Probes can be filtered and/or detected

Who is measuring the Internet?

• Businesses do a great deal of measurement– Mostly do not share with the research community– examples:

• Akamai: http delay from server side• HP (Mercury): http delay from client side • Google: everything

• Academia and Research institutes– Publish papers, but data may not be always available

• Internet Statistics and Metrics Analysis (ISMA)– CAIDA attempt to create a global meta-data database

Publishing Internet Measurement Studies

• All major networking conferences & journals accept measurement papers– ACM SIGCOMM, IEEE INFOCOM, ACM

SIGMETRICS

• Dedicated meetings:– ACM Internet Measurement Conf. (IMC, IMW)– Passive & Active Measurements Conf. (PAM)– TridentCom

Active Measurement Techniques

Active Probes

• Active probes send stimulus (packets) into the network and then measure the response– Done on network, transport and application layers

• Active probes are useful to measure various things:– Delay, delay jitter, and loss

– Topology and routing behavior

– Capacity, bandwidth, and throughput

Simple delay/loss probing with ping

C:\>ping www.fer.hr

Pinging www.fer.hr [161.53.72.111] with 32 bytes of data:

Reply from 161.53.72.111: bytes=32 time=113ms TTL=49Reply from 161.53.72.111: bytes=32 time=111ms TTL=49Reply from 161.53.72.111: bytes=32 time=113ms TTL=49Reply from 161.53.72.111: bytes=32 time=118ms TTL=49

Ping statistics for 161.53.72.111: Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),Approximate round trip times in milli-seconds: Minimum = 111ms, Maximum = 118ms, Average = 113ms

ICMP

ICMP is the IP error diagnosis protocol.

IP header

TypeCode

Checksum

Sequence number

Any ICMP data

ICMP Message Types

Type No.Meaning

0Echo reply

3Destination unreachable

4Source quench

5Redirect

8Echo

9Router advertisement

10Router solicitation

11Time exceeded

12Parameter problem

13Timestamp

14Timestamp reply

15Information requeste

16Information reply

PING

Application layer “ping”

• One can generate application layer messages to test application reaction time

• Most common:– TCP SYN message to port 80

traceroute

• Useful to learn the route characteristics between two hosts.

• Sends a series of probes to successive nodes along a route to an intended destination and records the source address and time delay of the message returned by each.

• Based on ICMP “TTL expired” message

IP datagram format

ver length

32 bits

data (variable length,typically a TCP

or UDP segment)

16-bit identifier

Internet checksum

time tolive

32 bit source IP address

IP protocol versionnumber

header length (bytes)

max numberremaining hops

(decremented at each router)

forfragmentation/reassembly

total datagramlength (bytes)

upper layer protocolto deliver payload to

head.len

type ofservice

“type” of data flgsfragment

offsetupper layer

32 bit destination IP address

Options (if any) E.g. timestamp,record routetaken, pecifylist of routers to visit.

ICMP Message Types

Type No.Meaning

0Echo reply

3Destination unreachable

4Source quench

5Redirect

8Echo

9Router advertisement

10Router solicitation

11Time exceeded

12Parameter problem

13Timestamp

14Timestamp reply

15Information requeste

16Information reply

traceroute

Type Code description3 0 dest. network unreachable3 1 dest host unreachable3 2 dest protocol unreachable3 3 dest port unreachable3 6 dest network unknown3 7 dest host unknown

traceroute

Regular UDP packets• successive TTLs

ICMP “TTL expired” message

ICMP “port unreachable” message

timeA B C D E

traceroute versions

• UNIX: – default send UDP packets

• Start at port 33435, and increment port per packet!

– traceroute –l sends ICMP “ECHO request”– tcptraceroute uses TCP SYN messages

• If port is close gets RST reply• If port is open gets SYN ACK and reply with RST• Best to overcome firewalls

• Windows– ICMP “ECHO request”

C:\>tracert www.fer.hr

Tracing route to www.fer.hr [161.53.72.111]over a maximum of 30 hops:

1< 1 ms <1 ms <1 ms 192.168.200.254 2 19 ms 20 ms 19 ms vxr.tau.ac.il [132.66.8.10]

3 17 ms 22 ms 20 ms c6509.tau.ac.il [132.66.8.20] 4 21 ms 19 ms 19 ms tel-aviv.tau.ac.il [132.66.4.1]

5 19 ms 23 ms 18 ms gp1-tau-fe.ilan.net.il [128.139.191.70] 6 20 ms 20 ms 20 ms iucc.il1.il.geant.net [62.40.103.69]

7 69 ms 69 ms 69 ms il.it1.it.geant.net [62.40.96.154] 8 82 ms 82 ms 82 ms it.ch1.ch.geant.net [62.40.96.33]

9 101 ms 98 ms 98 ms ch.at1.at.geant.net [62.40.96.1] 10 105 ms 105 ms 105 ms at.hu1.hu.geant.net [62.40.96.178] 11 117 ms 112 ms 113 ms hu.hr1.hr.geant.net [62.40.96.145]

12 113 ms 115 ms 115 ms carnet-gw.hr1.hr.geant.net [62.40.103.218] 13 120 ms 122 ms 123 ms 193.198.228.6

14 114 ms 112 ms 119 ms 193.198.229.10 15 120 ms 119 ms 119 ms 161.53.16.14

16 114 ms 114 ms 113 ms duality.cc.fer.hr [161.53.72.111]

Trace complete.

C:\>tracert www.colbud.hu

Tracing route to www.colbud.hu [81.182.250.153]over a maximum of 30 hops:




7 91 ms 92 ms 92 ms il.nl1.nl.geant.net [62.40.96.117] 8 97 ms 97 ms 97 ms nl.de1.de.geant.net [62.40.96.101]

9 95 ms 96 ms 93 ms ffm-b2-pos2-3.telia.net [213.248.77.89] 10 96 ms 96 ms 150 ms ffm-bb2-pos2-3-0.telia.net [213.248.64.177]

11 110 ms 112 ms 114 ms bpt-b1-pos2-0.telia.net [213.248.64.26] 12 * * * Request timed out.

13 112 ms 110 ms 111 ms 10ge-0-0.core0-ip2.net.telekom.hu [145.236.85.2] 14 112 ms 114 ms 110 ms tenge1-2.core0.adatpark.hu [145.236.89.10]

15 114 ms 112 ms 114 ms fixip-lns2.adatpark.hu [195.228.253.58] 16 120 ms 122 ms 124 ms 153-250-182-81.adsl-fixip.axelero.hu [81.182.250.153]

Trace complete.

Probing for link characteristics

• Packet dispersion techniques can be used to infer characteristics of each link along an Internet path.– Bandwidth, queuing delays, propagation delay– Cross traffic may cause problem

• Many tools are available:– bprobe [CC97], clink [D99], nettimer [LB99],

pathchar [J97], pchar [M00], pathrate [DRM01]

Capacity

• Maximum IP layer throughput that a flow can get, without any cross traffic

source sink

link 1link 2

link 3

• Ci = capacity of link i

• Path capacity C=mini{Ci}

Available Bandwidth

• Maximum IP layer throughput that a flow can get, given (stationary) cross traffic

source sink

link 1link 2

link 3

• ui = utilization of link i

• Path available bandwidth A=mini{Ci(1- ui)}

Packet Pair Dispersion

• Packet transmission time: τ=L/C• Send two packets back-to-back• Measure dispersion at the reciever• Estimate C as L/

• But cross-traffic ‘noise’ can effect .

L/CL/CL/3C

C 3C

Pathchar

• Developed by Van Jacobson to: “allows any user to find the bandwidth, delay, average queue and loss rate of every hop between any source & destination on the Internet”

• Measure the path hop by hop– Default: 32 probes per hop

Self-Loading Periodic Streams (SLoPS) [Jain Dovrolis 02]

• SND sends a periodic UDP packet stream at rate R.• R=L/T, L=packet size, T=period, K=number of packets• Measure one way delay (OWD): Dk=tarrive-tsend

• OWD variation: Dk=Dk+1-Dk (independent of clock

offset)• With stationarity & fluid model for the cross traffic, and

FIFO queues:

A Rif 0

if 0 ARD k

Illustration of SLoPS

Periodic Stream: K packets, size L bytes, rate R = L/T

Trends in Real Data

U. Oregon to U. Delaware (12 hops)

A=74Mbps (MRTG), K=100, T=100S, L=1200B

R= 96Mbps and 37Mbps

When RA

Passive Measurement Techniques

Passive packet measurement

• Capture packets as they pass by– Packet capture applications (tcpdump) on hosts use packet

capture filter• Requires access to the wire

– Promiscuous mode or mirror ports to see other traffic

– Hardware-bases solutions• Endace, Inc.’s DAG cards OC12/48/192 (0.622/2.5/10Gbps)�• Programmable NIC cards (<$100)

• Issues:– Timestamps– Data volumes– Privacy

tcpdump

• Can capture entire packet or n first bytes

• Timestamps each packet

• Can filter based on any combination of header field

12:40:18.501228 IP bakara.eng.tau.ac.il.23 > amirotem-pc.eng.tau.ac.il.2260: P 1:3(2) ack 1 win 8760 (DF)12:40:18.692431 IP amirotem-pc.eng.tau.ac.il.2260 > bakara.eng.tau.ac.il.23: . ack 3 win 64162 (DF)

12:40:18.692775 IP bakara.eng.tau.ac.il.23 > amirotem-pc.eng.tau.ac.il.2260: P 3:10(7) ack 1 win 8760 (DF)

12:40:18.893601 IP amirotem-pc.eng.tau.ac.il.2260 > bakara.eng.tau.ac.il.23: . ack 10 win 64155 (DF)

Full Packet Capture

12:22:42.401784 IP (tos 0x0, ttl 128, id 37074, len 41) AMIROTEM.dummy.net.3214 > bakara.eng.tau.ac.il.23: P [tcp sum ok] 3535692137:3535692138(1) ack 1410929928 win 16196 (DF)

0x0000 4500 0029 90d2 4000 8006 2d02 c0a8 c803 E..)[email protected] 8442 300c 0c8e 0017 d2be 6169 5419 1508 .B0.......aiT...0x0020 5018 3f44 1d9e 0000 6c P.?D....l12:22:42.426889 IP (tos 0x0, ttl 252, id 33630, len 41) bakara.eng.tau.ac.il.23 >

AMIROTEM.dummy.net.3214: P [tcp sum ok] 1:2(1) ack 1 win 9324 (DF)0x0000 4500 0029 835e 4000 fc06 be75 8442 300c E..).^@....u.B0.0x0010 c0a8 c803 0017 0c8e 5419 1508 d2be 616a ........T.....aj0x0020 5018 246c 3875 0000 6c88 8888 8888 P.$l8u..l.....12:22:42.600874 IP (tos 0x0, ttl 128, id 37075, len 41) AMIROTEM.dummy.net.3214 >

bakara.eng.tau.ac.il.23: P [tcp sum ok] 1:2(1) ack 2 win 16195 (DF)0x0000 4500 0029 90d3 4000 8006 2d01 c0a8 c803 E..)[email protected] 8442 300c 0c8e 0017 d2be 616a 5419 1509 .B0.......ajT...0x0020 5018 3f43 169d 0000 73 P.?C....s12:22:42.617003 IP (tos 0x0, ttl 252, id 33631, len 41) bakara.eng.tau.ac.il.23 >

AMIROTEM.dummy.net.3214: P [tcp sum ok] 2:3(1) ack 2 win 9324 (DF)0x0000 4500 0029 835f 4000 fc06 be74 8442 300c E..)[email protected] c0a8 c803 0017 0c8e 5419 1509 d2be 616b ........T.....ak0x0020 5018 246c 3173 0000 7388 8888 8888 P.$l1s..s.....

Passive IP flow measurement

• An IP flow is defined by the five-tuple:– src addr, src port, dst addr, dst port, protocol

• Cisco’s NetFlow– Part of the IOS – Provide template based flow records

• Many tools can manipulate NetFlow data

FlowScan [Plonka00]

• Combines flow collection engine, database, visualization tool

• Provides a near real-time visualization of network traffic

• Breaks down traffic into well known service or application

FlowScan Examples

)May 2005(

Analysis of Flows

• Examining flows of packets one can determine OOO packets:– Losses

– Reorders

– TCP state machine

– Retransmissions

– Duplicates

• Analysis can be done on 1- or 2-directional flows

Local ISP

Diagnostic node

Internet

Unidirectional Flows

• Evaluates TCP seq. # and IP-ID patterns– Assumption: the sender’s IP ID forms a monotonic increasing sequence

Brosh&Shavitt, Infocom’05

HTTP Logs

• Have data about the client IP, transaction time, command (GET/POST), return code, bytes transferred, referrer, metadata (browser

type, OS, languages, etc.)

• Tools are available to analyze HTTP logs– Webalizer

24.77.192.99 - - [15/May/2005:23:54:59 +0300] "GET /science_down.gif HTTP/1.1" 200 1138 "http://www.netdimes.org/science.html" "Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.7.7) Gecko/20050414 Firefox/1.0.3"68.231.117.28 - - [15/May/2005:23:52:05 +0300] "GET /ipmap.png HTTP/1.1" 200 4874697 "http://slashdot.org/" "Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.7) Gecko/20050414 Firefox/1.0.3"24.236.177.187 - - [15/May/2005:23:55:00 +0300] "GET /home_up.gif HTTP/1.1" 200 1096 "http://www.netdimes.org/" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.1.4322)"24.236.177.187 - - [15/May/2005:23:55:00 +0300] "GET /AboutUs_up.gif HTTP/1.1" 200 1169 "http://www.netdimes.org/" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.1.4322)"24.77.192.99 - - [15/May/2005:23:55:00 +0300] "GET /Install_down.gif HTTP/1.1" 200 1219 "http://www.netdimes.org/science.html" "Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.7.7) Gecko/20050414 Firefox/1.0.3"69.141.103.137 - - [15/May/2005:23:54:50 +0300] "POST /DIMES/server HTTP/1.1" 200 3 "-" "Java/1.4.1_03"24.236.177.187 - - [15/May/2005:23:55:00 +0300] "GET /news_up.gif HTTP/1.1" 200 1086 "http://www.netdimes.org/" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.1.4322)"24.236.177.187 - - [15/May/2005:23:55:00 +0300] "GET /community_up.gif HTTP/1.1" 200 1199 "http://www.netdimes.org/" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.1.4322)"24.236.177.187 - - [15/May/2005:23:55:00 +0300] "GET /datastat_up.gif HTTP/1.1" 200 1233 "http://www.netdimes.org/" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.1.4322)"24.236.177.187 - - [15/May/2005:23:55:00 +0300] "GET /science_up.gif HTTP/1.1" 200 1126 "http://www.netdimes.org/" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.1.4322)"71.106.2.53 - - [15/May/2005:23:55:00 +0300] "GET /favicon.ico HTTP/1.1" 200 5694 "-" "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.8) Gecko/20050511 Firefox/1.0.4"62.179.197.156 - - [15/May/2005:23:54:02 +0300] "GET /ipmap.png HTTP/1.1" 200 4874697 "http://slashdot.org/" "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.8) Gecko/20050511 Firefox/1.0.4"24.236.177.187 - - [15/May/2005:23:55:00 +0300] "GET /Install_up.gif HTTP/1.1" 200 1219 "http://www.netdimes.org/" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.1.4322)"24.236.177.187 - - [15/May/2005:23:55:00 +0300] "GET /EVERGROW40.gif HTTP/1.1" 200 4089 "http://www.netdimes.org/" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.1.4322)"195.252.52.155 - - [15/May/2005:23:55:00 +0300] "GET /science_down.gif HTTP/1.1" 200 1138 "http://www.netdimes.org/science.html" "Mozilla/5.0 (Windows; U; Windows NT 5.1; sv-SE; rv:1.7.6) Gecko/20050318 Firefox/1.0.2"

HTTP Log Example

[root@jupiter httpd]# grep "GET / " access_log |tail -1068.54.223.47 - - [19/May/2005:12:36:20 +0300] "GET / HTTP/1.1" 200 14067 "-" "Mozilla/4.0 (compatible;

MSIE 6.0; Windows NT 5.1; .NET CLR 1.1.4322)"132.76.80.118 - - [19/May/2005:12:49:44 +0300] "GET / HTTP/1.1" 304 -

"http://www.eng.tau.ac.il/~shavitt/" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; .NET CLR 1.1.4322)"

24.169.148.213 - - [19/May/2005:13:06:58 +0300] "GET / HTTP/1.1" 200 14067 "-" "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.8) Gecko/20050511 Firefox/1.0.4"

84.170.181.64 - - [19/May/2005:13:07:14 +0300] "GET / HTTP/1.1" 200 14067 "http://www.google.de/search?hl=de&q=dimes&meta=" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)"

130.240.136.220 - - [19/May/2005:13:07:25 +0300] "GET / HTTP/1.1" 304 - "-" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.1.4322)"

81.72.13.30 - - [19/May/2005:13:11:00 +0300] "GET / HTTP/1.1" 200 14067 "http://www.miranet.it/php/Articolo.php?id=708" "Mozilla/4.0 (compatible; MSIE 6.0; Windows 98)"

194.78.199.123 - - [19/May/2005:13:13:44 +0300] "GET / HTTP/1.1" 200 14067 "-" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0; .NET CLR 1.1.4322)"

82.152.182.12 - - [19/May/2005:13:23:10 +0300] "GET / HTTP/1.1" 200 14067 "-" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)"

80.119.126.44 - - [19/May/2005:13:38:08 +0300] "GET / HTTP/1.1" 200 14067 "-" "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.8) Gecko/20050511 Firefox/1.0.4"

80.250.186.101 - - [19/May/2005:13:46:14 +0300] "GET / HTTP/1.1" 200 14067 "http://distributed.ru/forum/?a=topic&topic=583" "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.8) Gecko/20050511 Firefox/1.0.4"

Example of Log Analysis

June 5th, 2005

Webalizeraccess analysis

MultiQ

• Analyzing incoming packet streams

• Gaps between packets are used to calculate bottleneck link speeds

• Multiple bottlenecks can be inferred

M&M, MIT

How does it work?

• 50% of traffic is comprised of 1500B packets

• Behavior at the second bottleneck:

Keep b.n. gap

Gap shifts reveal2nd bottleneck

“white noise”

Effect on dist.:

Three bottlenecks with one strike

Nettimer: A Tool for Measuring Bottleneck Link Bandwidth

Kevin Lai and Mary Baker, "Nettimer: A Tool for Measuring Bottleneck Link Bandwidth", USENIX Symp. on Internet Tech. and Sys., March 2001.

Topology Discovery









14 114 ms 112 ms 119 ms 193.198.229.10 15 120 ms 119 ms 119 ms 161.53.16.14


Trace complete.

private network

Tel Aviv Uni.

ILAN

DANTE

HR-ZZ

CARnet

AS378

AS20965GEANT

MACHBA

CARnet

AS2108

378 20965 2108

from IP to AS routes

How to map IP to AS?

• BGP announcements• Use public databases:

– Internet Routing Registry (IRR), http://www.irr.net

– whois servers

• Commercial databases– MaxMind, etc.

• Problem: incomplete and out-of-date• Due to acquisitions, mergers, break-ups of institutions

A

What is the AS level traceroute?

CBA-B-C

A CBC-B-A

Are A and C neighbor ASes?

What AS does the middle router belong to, B or C?

The Internet Structure

routers


The AS graph


The AS graph The PoP level graph

Delay Measurements









14 114 ms 112 ms 119 ms 193.198.229.10 15 120 ms 119 ms 119 ms 161.53.16.14


Trace complete.

Minimum delay of a link

Linkdelay19-22-12491316771727-6

Min.01917191820698298105112113120112119113

Negative delays

-150 -100 -50 0 50 100 150 200 2500

500

1000

1500

2000

2500

3000

3500

4000

4500

5000Link Delay Measurements Histogram

Link delay [ms]

Dis

trib

ution o

f th

e d

ela

y

am

ong 1

ms b

ins

A delay of a link inside TAU

negative delay

-300 -200 -100 0 100 200 30010

3

104

105

106

107

108

109

1010

AutoCorrelation lag

Histogram AutoCorrelation

autocorr of new histogram

autocorr of "sampled" histogram

Auto-Correlation Histogram

Why periodic?

int gettimeofday(struct timeval* tv, struct timezone *tz){

if(!tv) return -1; struct _timeb timebuffer; _ftime(&timebuffer);

tv-<tv_sec = timebuffer.time; tv-<tv_usec = timebuffer.millitm * 1000 + 500; return 0;

}

Maybe something wrong with the code?

millisecond accuracy

translate to seconds

New vs. Old timing routines

-100 -80 -60 -40 -20 0 20 40 60 80 1000

0.5

1

1.5

2

2.5x 10

4 Link delay measurements histogram

Delay [ms]

-100 -80 -60 -40 -20 0 20 40 60 80 1000

1000

2000

3000

4000

5000

6000

Delay [ms]

Old Version

New Version

-300 -200 -100 0 100 200 30010

3

104

105

106

107

108

109

1010

AutoCorrelation lag

Histogram AutoCorrelation

autocorr of new histogram

autocorr of "sampled" histogram

Auto-Correlation Histogram

Why periodic?

How to define distance between ASes?

Maybe the same as between nodes?• The distance between two ASes will be the distance

between the two border routers connecting them

20ms 17ms 26ms 40ms 35ms 89ms 79ms 91ms

AS 378 AS 1248 AS 701

14ms ?









14 114 ms 112 ms 119 ms 193.198.229.10 15 120 ms 119 ms 119 ms 161.53.16.14


Trace complete.

private network

Tel Aviv Uni.

ILAN

DANTE

HR-ZZ

CARnet

AS378

AS20965GEANT

MACHBA

CARnet

AS2108

378 20965 2108

from IP to AS routes

2ms

GEANT 2

DIMES AS distance definition (1)

• Define the following distances:– MaxAS(n) – the maximum delay to a node in AS n.– MinAS(n) – the minimum delay to a node in AS n.

• For AS edge (src,dest) define the distances:MinASEdge(src,dest) = MinAS(dest)-MaxAS(src) MaxASEdge(src,dest) = MaxAS(dest)-MaxAS(src) – All distances are positive.

• Define: ASDiameter(n) = MaxAS(n)– MinAS(n)

DIMES AS distance definition (2)


MinASEdge(378,1248) = 9ms

MaxASEdge(378,1248) = 63ms

MinASEdge(1248,701) = 1ms (non negative.)

MaxASEdge(1248,701) = 56ms

AS 378 AS 1248 AS 701

DIMES AS Diameter definition


AS 378 AS 1248 AS 701

diameter = 9ms diameter = 54ms diameter = 12ms

Measurement Projects

ETOMIC(Evergrow Traffic Observatory Measurement InfrastruCture)

http://www.etomic.org

• Active precise one-way delay measurement.• Specialized hardware.• With packet train techniques one can

– Estimate available bandwidth

– Bottleneck capacity

– Perform network tomography

• 18 boxes were deployed in Europe.• More have been deployed this year

ETOMIC Deployment

Hardware Structure

• A PC with a – DAG card

• high precision sampling hardware

• high precision packet train generation

– GPS connection• For synchronized timing

The GPS module

• Garmin 35HVS GPS reciever

• 1 s PPS signal• RS 232 – RS 422

converter – max 100m cable

GPS

RS232-<422RS232-<422

RS422-<232RS422-<232

Serial portSerial port

DAG PPSDAG PPS

PCPC

The Endace DAG 3.6GE card

• PCI bus – 32 bit 33 Mhz

• Single port full packet capture at 10/100/1000 Mbit/s

• Precise timestamping

• Burst of patterned traffic generator – sending special packets at 10/100/1000 Mbit/s

ATOMIC -> ANME

Skitterhttp://www.caida.org/tools/measurement/skitter

• Primarily intended to be used to measure forward IP paths (each ‘hop’) from a source to many destinations.

• traceroute based• Based on FreeBSD box with kernel

modification for timestamp accuracy.• Deployment: 20-30 skitter hosts, worldwide

(Half in the USA).

Skitter Goals

• Measure Forward IP Pathsskitter records each hop from a source to many destinations. by incrementing the "time to live" (TTL) of each IP packet header and recording replies from each router (or hop) leading to the destination host.

• Measure Round Trip Timeskitter collects round trip time (RTT) along with path (hop) data. skitter uses ICMP echo requests as probes to a list of IP destinations.

• Track Persistent Routing Changesskitter data can provide indications of low-frequency persistent routing changes. Correlations between RTT and time of day may reveal a change in either forward or reverse path routing.

• Visualize Network ConnectivityBy probing the paths to many destinations IP addresses spread throughout the IPv4 address space, skitter data can be used to visualize the directed graph from a source to much of the Internet.

Skitter Visualization

2003:

12,517 node

35,334 edges

RTT and loss plot

Archipelago (Ark)

• 43 monitors– 3 commercial

• IPv4 & IPv6

• 25th, 50th, and 75th percentiles

RouteViewshttp://www.routeviews.org

• Peers with ~70 ASes (mostly backbones) to collect their BGP paths

• The largest and most reliable source of AS level routing and interconnectivity.

Animating BGP Routing

BGP Routing Table Growth

NLANRhttp://www.nlanr.net

• The National Laboratory for Applied Network Research (NLANR)

• Lots of measurement data• Active Measurement Project (AMP)

– ~150 universities with high performance connection measure to each other.

• Passive Measurement and Analysis (PMA)– Header taken daily from OC3 - OC48 speed links.

Ono

• A plugin for the Vuze (Azureus) BitTorrent Client

• 3.5M measurements a day

• Over 3000 ASes a year– Few hundreds of measurement per client– Measure only to other clients

iPlane An Information Plane for Distributed Services

• Performs traceroutes from PlanetLab nodes and traceroute servers to construct a router interface-level Internet map.

• Clustering interfaces into PoPs– Based on TTL response time

• Latency prediction

PlanetLab

• 1080 nodes over 496 (academic) sites

• Bare bone machines. Load your own tool.

• Host various measurement projects:– DIMES – iPlane– ScriptRoute: (flexible scripts)

https://www.planet-lab.org/

Scamper

A tool for network measurement

• IPv4 & IPv6

• Parallel measurements

• Measurement rate control

• Measurement type: UDP, ICMP, TCP, UDP-paris, and ICMP-paris. – By default, UDP is used.

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