Mathematical Problems in Engineering
T : Parameters of OneProbe.
Parameters 𝑧 (bytes) 𝑀 (bytes) 𝑚 (bytes) 𝑒 (seconds) 𝑟 (pkt/s)
Value s
IPv packets are disordered, but also provide a basis for
investigating TCP behaviors in IPv world.
3. Methodologies
In this section, we rst take a look at the probing tool,
OneProbe. en we describe our probing method.
3.1. Overview of OneProbe. OneProbe is a reliable and metric-
rich path monitoring method based on TCP []. We use
HTTP/OneProbe,whichsendslegitimateHTTP GET request
in the TCP data probes to induce HTTP response messages
to measure delay, packet-loss rate, and packet reordering
rate. Each probe of OneProbe consists of two customized
back-to-back packets, applied to measure the performance of
the forward link. When probes arrive at remote-ends, they
will induce remote endpoints to send back two back-to-back
packets, which are used to measure the performance of the
reverse link. In this study, the values of the forward link
andreverselinkaremergedtoevaluatepacket-lossrateand
packet reordering rate. When using OneProbe,weshould
set some parameters with appropriate values. As shown in
Table , 𝑧 refers to the size of the packets that will be captured
for performance analysis. 𝑀represents the size of the probing
packets, while 𝑚 represents the size of the response packets.
Parameter of 𝑒 is used to control how long the probing will
last. We denote 𝑟 the sending rate of the probing packets. In
our experiment, we send probing packets in one second. In
addition to these primary parameters, we also need a source
address, a destination address, and its corresponding URL
(Uniform Resource Locator) to launch a OneProbe process.
3.2. Probing Method. Based on OneProbe, we design a prob-
ing method, which can persistently evaluate the interdomain
performance of an IPv network. Our probing method
mainly contains three phases, that is, obtaining URLs, clas-
sifying URLs, and probing.
(1) Obtaining URLs. We rst nd the URLs that meet the
requirements of OneProbe. To guarantee the accuracy of
probing, the object of each URL is well over Kbytes [].
BecauseofprobingsuchkindofURLs,wecaninduce
sucient number of response packets. We download top
M websites from Alexa [] and obtain desirable URLs by
crawling these websites. In addition, to make comparison
between IPv and IPv, only the URLs supporting both IPv
andIPvaccessarechoseninourstudy.
(2) Classifying URLs. Forthesakeofanalysis,wedividethe
URLs into ve groups in terms of the ve Regional Internet
Registries (RIRs (RIR is an organization that manages the
allocation and registration of IP addresses and autonomous
system numbers. RIR divides the world into ve RIRs,
including African Network Information Center (AFRINIC),
American Registry for Internet Numbers (ARIN), Asia-
Pacic Network Information Centre (APNIC), Latin America
and Caribbean Network Information Centre (LACNIC),
and R
´
eseaux IP Europ
´
eens Network Coordination Centre
(RIPENCC))), that is, APNIC, ARIN, AFRINIC, LACNIC,
and RIPENCC. To this end, we explore the addresses of these
destination URLs, and match these address to the prexes
that have been assigned to the ve RIRs [].
(3) Probing. Our probing host locates in CERNET []. To
avoid cross impact caused by too many synchronous probing
packets, we choose no more than URLs from each RIR
randomly and launch no more than OneProbe processes
synchronously at each time. Note that these URLs belong to
dierent websites and servers. For each RIR, we use OneProbe
to probe the destination URLs enabled with both IPv and
IPv for minutes ( minutes for IPv, minutes for IPv)
inonepollingcycle.atistosay,itcostsminutestoprobe
all the ve RIRs one aer another. erefore, we denote an
hour as a polling cycle.
4. Performance Analysis
According to the probing methods depicted in Section , we
conduct a case study on IPv performance from four aspects,
that is, reachability, delay, packet loss, and packet reordering.
In this study, one-week probing data is gathered and used.
ere are polling cycles during the one-week observation.
4.1. Reachability. Reachability is a basic performance metric
for network operation and management. ere are many
reasons that may cause network interruption, such as routing
policy adjustment, security policy control, physical link
failure, and intermediate node failure. We use interrupts and
interrupt rate to describe the reachability. Interrupts denotes
thenumberofdisconnectsbetweentheprobingclientand
probed destination URLs. Interrupt rate = interrupts/(the
number of polling cycles ∗ the number of URLs).
As shown in Table , RIPENCC of IPv has the most
number of interrupts. Interrupt rates of APNIC and LACNIC
are lower than those of the other three RIRs, while, as shown
in Table , interrupt rates of IPv in APNIC and LACNIC
are higher than those of the other three RIRs. In APNIC and
LACNIC, IPv performs better than IPv. However, the total
Interrupts of IPv are , while the number of IPv is .
Overall,thereachabilityofIPvisbetterthanthatofIPv.
4.2. Packet Delay. We use round trip time (RTT) to describe
the time overhead (i.e., delay) of a packet that goes to the
destination and returns to the source.