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Bandwidth Metrics and
Measurement Tools
Xin, Lu
High-Performance Computing Group
Computer Science University of Windsor
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Bandwidth Metrics
NMWG divide bandwidth into four sub-
metrics:
Bandwidth Capacity Achievable Bandwidth
Available Bandwidth
Bandwidth Utilization
FOR MORE INFO...
http://www-didc.lbl.gov/NMWG
http://www-didc.lbl.gov/NMWG/docs/measurements.pdf
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Other Metric Terms
Throughput Throughput is the same as achievable bandwidth.
Bulk Transfer Capacity (BTC) Defined by RFC 3148
BTC = data_sent / elapsed_time
The throughput of a persistent TCP transfer.
Each of these metrics can be used to describe
the entire path (end-to-end) as well as paths
link (hop-by-hop)characteristics.
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Bandwidth Capacity vs.
Achievable Bandwidth Capacity is the maximum amount of data per time unit
that the link or path has available, when there is no
competing traffic.
Achievable bandwidth is the maximum amount of dataper time unit that a link or path can provide to an
application, given the current utilization, the protocol and
operating system used, and the end-host performance
capability and load. (Throughput )
Reference: [2]
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Bandwidth Capacity vs.
Achievable Bandwidth Cont. If a path consists of several links, the link with
the minimum transmission rate determinesthe capacity of the path.
While the link with the minimum unusedcapacity limits the achievable bandwidth. i.e.
at high-speed networks, hardwareconfiguration or software load on the endhosts actually limit the bandwidth delivered tothe application.
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Available Bandwidth vs.
Bandwidth Utilization Available bandwidth is the maximum amount of
data per time unit that a link or path can provide,given the current utilization.
Utilization is the aggregate capacity currentlybeing consumed on a link or path.
Available Bandwidth =
Bandwidth Capacity Bandwidth Utilization
Reference: [2]
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BTC vs. Available Bandwidth
Available Bandwidth is the amount of usable
bandwidth without affecting cross-traffic,
whereas, the BTC is measured by sendingas much packets as possible, limiting other
traffic.
BTC is simulating steady state persistent
flow, taking considerable time and overhead.
FOR MORE INFO...
RFC 3148 : A Frame Work for Defining Empirical Bulk
Transfer Capacity Metrics
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BTC vs. Available Bandwidth
Cont.
The BTC definition assumes an ideal TCP
implementation, actually, this doesnt exist,and what BTC measured is the variant of
achievable bandwidth.
FOR MORE INFO...
RFC 3148 : A Frame Work for Defining Empirical Bulk
Transfer Capacity Metrics
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Passive vs. Active measurement
Active measurement means that the tool
actively sends probing packets into the
network. Passive measurement tools monitors the
passing traffic without interfering.
Passive measurement is appreciated,
however, less reliable than active, as it
cant extract any data pass through it.
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Receiver-based vs. Sender-
based techniques Receiver-based (end-to-end)
techniques usually use the one-
direction TCP stream to probe thepath bandwidth.
Sender-based (echo-based)
techniques force the receiver to replythe ICMP query, UDP echo or TCP-
FIN.
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Sender-based technique
Advantage:
Flexible deployment.
Clock neednt synchronized at two ends.
Disadvantage:
ICMP and UDP echo packets usually be rate-limitedor filtered out by some routers.
Round-trip is much more possibility influenced bycross-traffic than that of one-way delay
Response packets may come back through adifferent path
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Receiver-based technique
Advantage:
More accurate than sender-based technique.
Disadvantage:
Difficult to deployment.
The clock have to be synchronized at twoends.
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Bandwidth Measurement
Technology Packet Dispersion technology
packet pair and packet train
Self-Loading Periodic streams (SLOPS)
Variable Packet Size (VPS)
technology
VPS even/odd
Tailgating technique
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Packet Dispersion Technique
Cont.Bottleneck bandwidth = packet size/ t
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Packet Dispersion Technique
Cont. If sender sends the packets as one
observation sample more than two, called
packet train. Tools usually apply robust statistical
filtering techniques to find valid samples.
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Packet pair vs. packet train
Packet train is more likely to be interferedby cross traffic than packet pair.
Packet train can be used to measure thebottleneck link that is multichannel whilepacket pair cant deal with.
Packet train can reduce the limitation of
clock resolution. Sophisticated tools apply both methods in
their implementation. i.e. Pathrate
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Packet Dispersion Technique
Cont.
FOR MORE INFO...
Bprobe and cprobe http://cs-people.bu.edu/carter/tools/Tools.html
Nettest http://www-didc.lbl.gov/pipechar
Tool
Name
Active/
Passive
Method-
ology
Protocol Metrics Path/Per-
link
bprobe Active Packetpair
ICMP BandwidthCapacity Path
cprobe Active Packet
pair
ICMP Bandwidthutilization
Path
Netest Active Packetpair
UDP Bandwidthcapacity Path
http://cs-people.bu.edu/carter/tools/Tools.htmlhttp://www-didc.lbl.gov/pipecharhttp://www-didc.lbl.gov/pipecharhttp://www-didc.lbl.gov/pipecharhttp://www-didc.lbl.gov/pipecharhttp://cs-people.bu.edu/carter/tools/Tools.htmlhttp://cs-people.bu.edu/carter/tools/Tools.htmlhttp://cs-people.bu.edu/carter/tools/Tools.html7/28/2019 Bandwidth Metrics
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Packet Dispersion Technique
Cont.
FOR MORE INFO...
Pathrate http://www.cc.gatech.edu/fac/Constantinos.Dovrolis
Pipecharhttp://www-didc.lbl.gov/pipechar
SProbe http://sprobe.cs.washington.edu
Pathrate Active Packet pair,packet train
UDP Bandwidthcapacity
Path
Pipechar
Active Packettrain UDPAvailable
bandwidth Per-link
Sprobe Active Packet
pair
TCP Bandwidthcapacity
Path
http://www.cc.gatech.edu/fac/Constantinos.Dovrolishttp://www-didc.lbl.gov/pipecharhttp://sprobe.cs.washington.edu/http://sprobe.cs.washington.edu/http://www-didc.lbl.gov/pipecharhttp://www-didc.lbl.gov/pipecharhttp://www-didc.lbl.gov/pipecharhttp://www.cc.gatech.edu/fac/Constantinos.Dovrolis7/28/2019 Bandwidth Metrics
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Self-Loading Periodic
Streams(SLOPS) Sender sends series of packets to the sink
at the rate of larger than the bottlenecklink available bandwidth.
Every packets get a timestamp at senderside.
Compare the difference of successive
packets timestamp and their arrival timesto infer the available bandwidth.
Rate-adjustment adaptive algorithm toconverge to the available bandwidth.
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Self-Loading Periodic Streams
Cont.
FOR MORE INFO...
Pathload http://www.cc.gatech.edu/fac/Constantinos.Dovrolis
Tool
Name
Active/
Passive
Method-
ology
Protocol Metrics Path/Per
-linkpathload Active SLOPS UDP Available
bandwidthPath
http://www.cc.gatech.edu/fac/Constantinos.Dovrolishttp://www.cc.gatech.edu/fac/Constantinos.Dovrolis7/28/2019 Bandwidth Metrics
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Variable Packet Size (VPS)
Technique Step1. Sender set TTL=1, send out the packet, and
wait for the ICMP TTL-exceeded packet back.
Step2. Upon receiving ICMP, estimate the RTT.
Estimate the RTT multiple times for various size
packets.The minimum RTT of various packets are
believed to be the valid sample.
Step3. The first link capacity is C=1/b , b is slope ofRTT graph.
Set the TTL=2,3n, repeat the process of step1 to 3, to
Calculate the C=1/bibi-1
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VPS technique cont.
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Even-odd VPS
The VPS probing technique is not altered,
Mathematical trick to improve reliability.
For each of the probing sizes, divide the setof samples into even and odd numbers.
Calculation is based on even-odd samples.
i.e. the even sample of link i, the odd sample
of link i+1.
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Tailgating Technique
Tailgating technique divides into two phrase:
Phase one: Like VPS probing, but for entire path
instead of per link.Phase two: (tailgating phase) The largest possible
non-fragmented packet followed by a tailgater
which is the smallest possible packet size (i.e
40 bytes). This causes the smaller packetalways queue behind the larger packet.Reference: Kevin Lai, Mary Baker Measuring Link Bandwidths
Using a Deterministic Model of Packet Delay ACM SIGCOMM 2000
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Tailgating Technique cont.
The following condition should met: The large packet should not be queued due to
cross traffic.
The large packet should have a TTL field set to L(1n).
The tailgater packet should be queued directlyafter the large packet on link L.
The tailgater packet should not queued afterhaving passing link L.
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VPS Technology
Bing http://www.cnam.fn/reseau/bing.html
Clink http://rocky.wellesley.edu/downey/clink/
Pcharhttp://www.emplyees.org/~bmah/software/pchar
Tool
Name
Active/
Passive
Method-
ology
Protocol Metrics Path/Per
-link
bing Active VPS ICMPBandwidth
capacity,loss, delay
Path
clink Active VPS/even-odd
UDP Bandwidthcapacity,
Loss
Path
Pchar Active VPS UDP,ICMP
Bandwidthcapacity,
Loss, delay
Per-link
http://www.cnam.fn/reseau/bing.htmlhttp://rocky.wellesley.edu/downey/clink/http://www.emplyees.org/~bmah/software/pcharhttp://www.emplyees.org/~bmah/software/pcharhttp://rocky.wellesley.edu/downey/clink/http://www.cnam.fn/reseau/bing.html7/28/2019 Bandwidth Metrics
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VPS Technology Cont.
Nettimerhttp://mosquitonet.stanford.edu/~laik/project/nettimer
Pathcharftp://ftp.ee.lbl.gov/pathchar/
Tool
Name
Active/
Passive
Method-
ology
Protocol Metrics Path/Per
-link
Nettimer Active,Passive
VPS/tailgating
TCP Bandwidthcapacity
Per-link
pathchar Active VPS/eve
n-odd
UDP,
ICMP
Bandwidth
capacity,
Loss, delay
Per-link
FOR MORE INFO...
http://mosquitonet.stanford.edu/~laik/project/nettimerftp://ftp.ee.lbl.gov/pathchar/ftp://ftp.ee.lbl.gov/pathchar/http://mosquitonet.stanford.edu/~laik/project/nettimer7/28/2019 Bandwidth Metrics
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TCP Simulation and Path Flooding
TCP simulation operates at two mode :UDP/ICMP with low TTL or ICMP echo/reply.It simulates the TCP of using slow-start
algorithm.
Path flooding method injects TCP/UDPpackets into the net as fast as possiblewithin the specific time.
To some degree, both TCP simulation andpath flooding are associated with BulkTransfer Capacity (BTC)metrics.
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Tool
Name
Active/
Passive
Method-
ology
Protocol Metrics Path/Per
-link
TReno Active TCPsimulation UDP,ICMPBTC Path
ttcp Active Path
flooding
TCP,
UDP
Achievable
bandwidthPath
iperf Active Pathflooding
TCP,UDP
Bandwidthcapacity,
Loss
Path
Netperf Active Path
flooding
TCP,
UDP
BTC, delay
throughputPath
TCP Simulation and Path Flooding Cont.
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TCP Simulation and Path Flooding Cont.
TReno
http://www.psc.edu/networking/treno_info.html
Iperfhttp://dast.nlanr.net/Project/Iperf
Netperf
http://www.netperf.org/netperf/NetperfPage.htmlttcp part of OS
ftp://ftp.arl.mil/pub/ttcp/
http://www.psc.edu/networking/treno_info.htmlhttp://dast.nlanr.net/Project/Iperfhttp://www.netperf.org/netperf/NetperfPage.htmlftp://ftp.arl.mil/pub/ttcp/ftp://ftp.arl.mil/pub/ttcp/http://www.netperf.org/netperf/NetperfPage.htmlhttp://dast.nlanr.net/Project/Iperfhttp://www.psc.edu/networking/treno_info.html7/28/2019 Bandwidth Metrics
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Bandwidth Measurement Tools
Con.Reference :
1.http://www.caida.org/tools/
2. Bruce Lowekamp, Brain Tierney, Les Cottrell, RichardHughes-Jones, Thilo Kielmann and Martin Swany. A
Hierarchy of Network Measurements for Grid
Applications and Services Document (draft) Global Grid
Forum NMWG Feb 17, 2003.
3. Rody Schoonderwoerd Network Performance
Measurement Tools a comprehensive comparison Nov.,
2002
http://www.caida.org/tools/http://www.caida.org/tools/