Internet Engineering Task Force (IETF) M. Georgescu
Request for Comments: 8219 L. Pislaru
Category: Informational RCS&RDS
ISSN: 2070-1721 G. Lencse
Szechenyi Istvan University
August 2017
Benchmarking Methodology for IPv6 Transition Technologies
Abstract
Benchmarking methodologies that address the performance of network
interconnect devices that are IPv4- or IPv6-capable exist, but the
IPv6 transition technologies are outside of their scope. This
document provides complementary guidelines for evaluating the
performance of IPv6 transition technologies. More specifically, this
document targets IPv6 transition technologies that employ
encapsulation or translation mechanisms, as dual-stack nodes can be
very well
tested using the recommendations of RFCs 2544 and 5180. The
methodology also includes a metric for benchmarking load scalability.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc8219.
Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction ....................................................4
1.1. IPv6 Transition Technologies ...............................4
2. Conventions Used in This Document ...............................6
3. Terminology .....................................................7
4. Test Setup ......................................................7
4.1. Single-Translation Transition Technologies .................8
4.2. Encapsulation and Double-Translation Transition
Technologies ...............................................8
5. Test Traffic ....................................................9
5.1. Frame Formats and Sizes ....................................9
5.1.1. Frame Sizes to Be Used over Ethernet ...............10
5.2. Protocol Addresses ........................................10
5.3. Traffic Setup .............................................10
6. Modifiers ......................................................11
7. Benchmarking Tests .............................................11
7.1. Throughput ................................................11
7.2. Latency ...................................................11
7.3. Packet Delay Variation ....................................13
7.3.1. PDV ................................................13
7.3.2. IPDV ...............................................14
7.4. Frame Loss Rate ...........................................15
7.5. Back-to-Back Frames .......................................15
7.6. System Recovery ...........................................15
7.7. Reset .....................................................15
8. Additional Benchmarking Tests for Stateful IPv6 Transition
Technologies ...................................................15
8.1. Concurrent TCP Connection Capacity ........................15
8.2. Maximum TCP Connection Establishment Rate .................15
9. DNS Resolution Performance .....................................15
9.1. Test and Traffic Setup ....................................16
9.2. Benchmarking DNS Resolution Performance ...................17
9.2.1. Requirements for the Tester ........................18
10. Overload Scalability ..........................................19
10.1. Test Setup ...............................................19
10.1.1. Single-Translation Transition Technologies ........19
10.1.2. Encapsulation and Double-Translation
Transition Technologies ...........................20
10.2. Benchmarking Performance Degradation .....................21
10.2.1. Network Performance Degradation with
Simultaneous Load .................................21
10.2.2. Network Performance Degradation with
Incremental Load ..................................22
11. NAT44 and NAT66 ...............................................22
12. Summarizing Function and Variation ............................23
13. Security Considerations .......................................23
14. IANA Considerations ...........................................24
15. References ....................................................24
15.1. Normative References .....................................24
15.2. Informative References ...................................25
Appendix A. Theoretical Maximum Frame Rates........................29
Acknowledgements...................................................30
Authors' Addresses ................................................30
1. Introduction
The methodologies described in [RFC2544] and [RFC5180] help vendors
and network operators alike analyze the performance of IPv4 and
IPv6-capable network devices. The methodology presented in [RFC2544]
is mostly IP version independent, while [RFC5180] contains
complementary recommendations that are specific to the latest IP
version, IPv6. However, [RFC5180] does not cover IPv6 transition
technologies.
IPv6 is not backwards compatible, which means that IPv4-only nodes
cannot directly communicate with IPv6-only nodes. To solve this
issue, IPv6 transition technologies have been proposed and
implemented.
This document presents benchmarking guidelines dedicated to IPv6
transition technologies. The benchmarking tests can provide insights
about the performance of these technologies, which can act as useful
feedback for developers and network operators going through the IPv6
transition process.
The document also includes an approach to quantify performance when
operating in overload. Overload scalability can be defined as a
system's ability to gracefully accommodate a greater number of flows
than the maximum number of flows that the Device Under Test (DUT) can
operate normally. The approach taken here is to quantify the
overload scalability by measuring the performance created by an
excessive number of network flows and comparing performance to the
non-overloaded case.
1.1. IPv6 Transition Technologies
Two of the basic transition technologies, dual IP layer (also known
as dual stack) and encapsulation, are presented in [RFC4213].
IPv4/IPv6 translation is presented in [RFC6144]. Most of the
transition technologies employ at least one variation of these
mechanisms. In this context, a generic classification of the
transition technologies can prove useful.
We can consider a production network transitioning to IPv6 as being
constructed using the following IP domains:
o Domain A: IPvX-specific domain
o Core domain: IPvY-specific or dual-stack (IPvX and IPvY) domain
o Domain B: IPvX-specific domain
Note: X,Y are part of the set {4,6}, and X NOT.EQUAL is NOT EQUAL to Y.
According
The transition technologies can be categorized according to the
technology used for core domain traversal, traversal of the
transition technologies can be categorized as follows: core domain:
1. Dual stack: Devices in the core domain implement both IP
protocols.
2. Single translation: In this case, the production network is
assumed to have only two domains: Domain A and the core domain.
The core domain is assumed to be IPvY specific. IPvX packets are
translated to IPvY at the edge between Domain A and the core
domain.
3. Double translation: The production network is assumed to have all
three domains; Domains A and B are IPvX specific, while the core
domain is IPvY specific. A translation mechanism is employed for
the traversal of the core network. The IPvX packets are
translated to IPvY packets at the edge between Domain A and the
core domain. Subsequently, the IPvY packets are translated back
to IPvX at the edge between the core domain and Domain B.
4. Encapsulation: The production network is assumed to have all
three domains; Domains A and B are IPvX specific, while the core
domain is IPvY specific. An encapsulation mechanism is used to
traverse the core domain. The IPvX packets are encapsulated to
IPvY packets at the edge between Domain A and the core domain.
Subsequently, the IPvY packets are de-encapsulated at the edge
between the core domain and Domain B.
The performance of dual-stack transition technologies can be fully
evaluated using the benchmarking methodologies presented by [RFC2544]
and [RFC5180]. Consequently, this document focuses on the other
three categories: single-translation, double-translation, and
encapsulation transition technologies.
Another important aspect by which IPv6 transition technologies can be
categorized is their use of stateful or stateless mapping algorithms.
The technologies that use stateful mapping algorithms (e.g., Stateful
NAT64 [RFC6146]) create dynamic correlations between IP addresses or
{IP address, transport protocol, transport port number} tuples, which
are stored in a state table. For ease of reference, IPv6 transition
technologies that employ stateful mapping algorithms will be called
"stateful IPv6 transition technologies". The efficiency with which
the state table is managed can be an important performance indicator
for these technologies. Hence, additional benchmarking tests are
RECOMMENDED for stateful IPv6 transition technologies.
Table 1 contains the generic categories and associations with some of
the IPv6 transition technologies proposed in the IETF. Please note
that the list is not exhaustive.
+---+--------------------+------------------------------------+
| | Generic category | IPv6 Transition Technology |
+---+--------------------+------------------------------------+
| 1 | Dual stack | Dual IP Layer Operations [RFC4213] |
+---+--------------------+------------------------------------+
| 2 | Single translation | NAT64 [RFC6146], IVI [RFC6219] |
+---+--------------------+------------------------------------+
| 3 | Double translation | 464XLAT [RFC6877], MAP-T [RFC7599] |
+---+--------------------+------------------------------------+
| 4 | Encapsulation | DS-Lite [RFC6333], MAP-E [RFC7597],|
| | | Lightweight 4over6 [RFC7596], |
| | | 6rd [RFC5569], 6PE [RFC4798], |
| | | 6VPE [RFC4659] |
+---+--------------------+------------------------------------+
Table 1: IPv6 Transition Technologies Categories
2. Conventions Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
Although these terms are usually associated with protocol
requirements, in this document, the terms are requirements for users
and systems that intend to implement the test conditions and claim
conformance with this specification.
3. Terminology
A number of terms used in this memo have been defined in other RFCs.
Please refer to the RFCs below for definitions, testing procedures,
and reporting formats.
o Throughput (Benchmark) [RFC2544]
o Frame Loss Rate (Benchmark) [RFC2544]
o Back-to-Back Frames (Benchmark) [RFC2544]
o System Recovery (Benchmark) [RFC2544]
o Reset (Benchmark) [RFC6201]
o Concurrent TCP Connection Capacity (Benchmark) [RFC3511]
o Maximum TCP Connection Establishment Rate (Benchmark) [RFC3511]
4. Test Setup
The test environment setup options recommended for benchmarking IPv6
transition technologies are very similar to the ones presented in
Section 6 of [RFC2544]. In the case of the Tester setup, the options
presented in [RFC2544] and [RFC5180] can be applied here as well.
However, the DUT setup options should be explained in the context of
the targeted categories of IPv6 transition technologies: single
translation, double translation, and encapsulation.
Although both single Tester and sender/receiver setups are applicable
to this methodology, the single Tester setup will be used to describe
the DUT setup options.
For the test setups presented in this memo, dynamic routing SHOULD be
employed. However, the presence of routing and management frames can
represent unwanted background data that can affect the benchmarking
result. To that end, the procedures defined in Sections 11.2 and
11.3 of [RFC2544] related to routing and management frames SHOULD be
used here. Moreover, the "trial description" recommendations
presented in Section 23 of [RFC2544] are also valid for this memo.
In terms of route setup, the recommendations of Section 13 of
[RFC2544] are valid for this document, assuming that IPv6-capable
routing protocols are used.
4.1. Single-Translation Transition Technologies
For the evaluation of single-translation transition technologies, a
single DUT setup (see Figure 1) SHOULD be used. The DUT is
responsible for translating the IPvX packets into IPvY packets. In
this context, the Tester device SHOULD be configured to support both
IPvX and IPvY.
+--------------------+
| |
+------------|IPvX Tester IPvY|<-------------+
| | | |
| +--------------------+ |
| |
| +--------------------+ |
| | | |
+----------->|IPvX DUT IPvY|--------------+
| |
+--------------------+
Figure 1: Test Setup 1 (Single DUT)
4.2. Encapsulation and Double-Translation Transition Technologies
For evaluating the performance of encapsulation and double-
translation transition technologies, a dual DUT setup (see Figure 2)
SHOULD be employed. The Tester creates a network flow of IPvX
packets. The first DUT is responsible for the encapsulation or
translation of IPvX packets into IPvY packets. The IPvY packets are
de-encapsulated/translated back to IPvX packets by the second DUT and
forwarded to the Tester.
+--------------------+
| |
+---------------------|IPvX Tester IPvX|<------------------+
| | | |
| +--------------------+ |
| |
| +--------------------+ +--------------------+ |
| | | | | |
+----->|IPvX DUT 1 IPvY |----->|IPvY DUT 2 IPvX |------+
| | | |
+--------------------+ +--------------------+
Figure 2: Test Setup 2 (Dual DUT)
One of the limitations of the dual DUT setup is the inability to
reflect asymmetries in behavior between the DUTs. Considering this,
additional performance tests SHOULD be performed using the single DUT
setup.
Note: For encapsulation IPv6 transition technologies in the single
DUT setup, the Tester SHOULD be able to send IPvX packets
encapsulated as IPvY in order to test the de-encapsulation
efficiency.
5. Test Traffic
The test traffic represents the experimental workload and SHOULD meet
the requirements specified in this section. The requirements are
dedicated to unicast IP traffic. Multicast IP traffic is outside of
the scope of this document.
5.1. Frame Formats and Sizes
[RFC5180] describes the frame size requirements for two commonly used
media types: Ethernet and SONET (Synchronous Optical Network).
[RFC2544] also covers other media types, such as token ring and Fiber
Distributed Data Interface (FDDI). The recommendations of those two
documents can be used for the dual-stack transition technologies.
For the rest of the transition technologies, the frame overhead
introduced by translation or encapsulation MUST be considered.
The encapsulation/translation process generates different size frames
on different segments of the test setup. For instance, the single-
translation transition technologies will create different frame sizes
on the receiving segment of the test setup, as IPvX packets are
translated to IPvY. This is not a problem if the bandwidth of the
employed media is not exceeded. To prevent exceeding the limitations
imposed by the media, the frame size overhead needs to be taken into
account when calculating the maximum theoretical frame rates. The
calculation method for the Ethernet, as well as a calculation
example, are detailed in Appendix A. The details of the media
employed for the benchmarking tests MUST be noted in all test
reports.
In the context of frame size overhead, MTU recommendations are needed
in order to avoid frame loss due to MTU mismatch between the virtual
encapsulation/translation interfaces and the physical network
interface controllers (NICs). To avoid this situation, the larger
MTU between the physical NICs and virtual encapsulation/translation
interfaces SHOULD be set for all interfaces of the DUT and Tester.
To be more specific, the minimum IPv6 MTU size (1280 bytes) plus the
encapsulation/translation overhead is the RECOMMENDED value for the
physical interfaces as well as virtual ones.
5.1.1. Frame Sizes to Be Used over Ethernet
Based on the recommendations of [RFC5180], the following frame sizes
SHOULD be used for benchmarking IPvX/IPvY traffic on Ethernet links:
64, 128, 256, 512, 768, 1024, 1280, 1518, 1522, 2048, 4096, 8192, and
9216.
For Ethernet frames exceeding 1500 bytes in size, the [IEEE802.1AC]
standard can be consulted.
Note: For single-translation transition technologies (e.g., NAT64) in
the IPv6 -> IPv4 translation direction, 64-byte frames SHOULD be
replaced by 84-byte frames. This would allow the frames to be
transported over media such as the ones described by the [IEEE802.1Q]
standard. Moreover, this would also allow the implementation of a
frame identifier in the UDP data.
The theoretical maximum frame rates considering an example of frame
overhead are presented in Appendix A.
5.2. Protocol Addresses
The selected protocol addresses should follow the recommendations of
Section 5 of [RFC5180] for IPv6 and Section 12 of [RFC2544] for IPv4.
Note: Testing traffic with extension headers might not be possible
for the transition technologies that employ translation. Proposed
IPvX/IPvY translation algorithms such as IP/ICMP translation
[RFC7915] do not support the use of extension headers.
5.3. Traffic Setup
Following the recommendations of [RFC5180], all tests described
SHOULD be performed with bidirectional traffic. Unidirectional
traffic tests MAY also be performed for a fine-grained performance
assessment.
Because of the simplicity of UDP, UDP measurements offer a more
reliable basis for comparison than other transport-layer protocols.
Consequently, for the benchmarking tests described in Section 7 of
this document, UDP traffic SHOULD be employed.
Considering that a transition technology could process both native
IPv6 traffic and translated/encapsulated traffic, the following
traffic setups are recommended:
i) IPvX only traffic (where the IPvX traffic is to be
translated/encapsulated by the DUT)
ii) 90% IPvX traffic and 10% IPvY native traffic
iii) 50% IPvX traffic and 50% IPvY native traffic
iv) 10% IPvX traffic and 90% IPvY native traffic
For the benchmarks dedicated to stateful IPv6 transition
technologies, included in Section 8 of this memo (Concurrent TCP
Connection Capacity and Maximum TCP Connection Establishment Rate),
the traffic SHOULD follow the recommendations of Sections 5.2.2.2 and
5.3.2.2 of [RFC3511].
6. Modifiers
The idea of testing under different operational conditions was first
introduced in Section 11 of [RFC2544] and represents an important
aspect of benchmarking network elements, as it emulates, to some
extent, the conditions of a production environment. Section 6 of
[RFC5180] describes complementary test conditions specific to IPv6.
The recommendations in [RFC2544] and [RFC5180] can also be followed
for testing of IPv6 transition technologies.
7. Benchmarking Tests
The following sub-sections describe all recommended benchmarking
tests.
7.1. Throughput
Use Section 26.1 of [RFC2544] unmodified.
7.2. Latency
Objective: To determine the latency. Typical latency is based on the
definitions of latency from [RFC1242]. However, this memo provides a
new measurement procedure.
Procedure: Similar to [RFC2544], the throughput for DUT at each of
the listed frame sizes SHOULD be determined. Send a stream of frames
at a particular frame size through the DUT at the determined
throughput rate to a specific destination. The stream SHOULD be at
least 120 seconds in duration.
Identifying tags SHOULD be included in at least 500 frames after 60
seconds. For each tagged frame, the time at which the frame was
fully transmitted (timestamp A) and the time at which the frame was
received (timestamp B) MUST be recorded. The latency is timestamp B
minus timestamp A as per the relevant definition from RFC 1242,
namely, latency as defined for store and forward devices or latency
as defined for bit forwarding devices.
We recommend encoding the identifying tag in the payload of the
frame. To be more exact, the identifier SHOULD be inserted after the
UDP header.
From the resulted (at least 500) latencies, two quantities SHOULD be
calculated. One is the typical latency, which SHOULD be calculated
with the following formula:
TL = Median(Li)
Where:
o TL = the reported typical latency of the stream
o Li = the latency for tagged frame i
The other measure is the worst-case latency, which SHOULD be
calculated with the following formula:
WCL = L99.9thPercentile
Where:
o WCL = the reported worst-case latency
o L99.9thPercentile = the 99.9th percentile of the stream-measured
latencies
The test MUST be repeated at least 20 times with the reported value
being the median of the recorded values for TL and WCL.
Reporting Format: The report MUST state which definition of latency
(from RFC 1242) was used for this test. The summarized latency
results SHOULD be reported in the format of a table with a row for
each of the tested frame sizes. There SHOULD be columns for the
frame size, the rate at which the latency test was run for that frame
size, the media types tested, and the resultant typical latency, and
the worst-case latency values for each type of data stream tested.
To account for the variation, the 1st and 99th percentiles of the 20
iterations MAY be reported in two separated columns. For a fine-
grained analysis, the histogram (as exemplified in Section 4.4 of
[RFC5481]) of one of the iterations MAY be displayed.
7.3. Packet Delay Variation
[RFC5481] presents two metrics: Packet Delay Variation (PDV) and
Inter Packet Delay Variation (IPDV). Measuring PDV is RECOMMENDED;
for a fine-grained analysis of delay variation, IPDV measurements MAY
be performed.
7.3.1. PDV
Objective: To determine the Packet Delay Variation as defined in
[RFC5481].
Procedure: As described by [RFC2544], first determine the throughput
for the DUT at each of the listed frame sizes. Send a stream of
frames at a particular frame size through the DUT at the determined
throughput rate to a specific destination. The stream SHOULD be at
least 60 seconds in duration. Measure the one-way delay as described
by [RFC3393] for all frames in the stream. Calculate the PDV of the
stream using the formula:
PDV = D99.9thPercentile - Dmin
Where:
o D99.9thPercentile = the 99.9th percentile (as described in
[RFC5481]) of the one-way delay for the stream
o Dmin = the minimum one-way delay in the stream
As recommended in [RFC2544], the test MUST be repeated at least 20
times with the reported value being the median of the recorded
values. Moreover, the 1st and 99th percentiles SHOULD be calculated
to account for the variation of the dataset.
Reporting Format: The PDV results SHOULD be reported in a table with
a row for each of the tested frame sizes and columns for the frame
size and the applied frame rate for the tested media types. Two
columns for the 1st and 99th percentile values MAY be displayed.
Following the recommendations of [RFC5481], the RECOMMENDED units of
measurement are milliseconds.
7.3.2. IPDV
Objective: To determine the Inter Packet Delay Variation as defined
in [RFC5481].
Procedure: As described by [RFC2544], first determine the throughput
for the DUT at each of the listed frame sizes. Send a stream of
frames at a particular frame size through the DUT at the determined
throughput rate to a specific destination. The stream SHOULD be at
least 60 seconds in duration. Measure the one-way delay as described
by [RFC3393] for all frames in the stream. Calculate the IPDV for
each of the frames using the formula:
IPDV(i) = D(i) - D(i-1)
Where:
o D(i) = the one-way delay of the i-th frame in the stream
o D(i-1) = the one-way delay of (i-1)th frame in the stream
Given the nature of IPDV, reporting a single number might lead to
over-summarization. In this context, the report for each measurement
SHOULD include three values: Dmin, Dmed, and Dmax.
Where:
o Dmin = the minimum IPDV in the stream
o Dmed = the median IPDV of the stream
o Dmax = the maximum IPDV in the stream
The test MUST be repeated at least 20 times. To summarize the 20
repetitions, for each of the three (Dmin, Dmed, and Dmax), the median
value SHOULD be reported.
Reporting format: The median for the three proposed values SHOULD be
reported. The IPDV results SHOULD be reported in a table with a row
for each of the tested frame sizes. The columns SHOULD include the
frame size and associated frame rate for the tested media types and
sub-columns for the three proposed reported values. Following the
recommendations of [RFC5481], the RECOMMENDED units of measurement
are milliseconds.
7.4. Frame Loss Rate
Use Section 26.3 of [RFC2544] unmodified.
7.5. Back-to-Back Frames
Use Section 26.4 of [RFC2544] unmodified.
7.6. System Recovery
Use Section 26.5 of [RFC2544] unmodified.
7.7. Reset
Use Section 4 of [RFC6201] unmodified.
8. Additional Benchmarking Tests for Stateful IPv6 Transition
Technologies
This section describes additional tests dedicated to stateful IPv6
transition technologies. For the tests described in this section,
the DUT devices SHOULD follow the test setup and test parameters
recommendations presented in Sections 5.2 and 5.3 of [RFC3511].
The following additional tests SHOULD be performed.
8.1. Concurrent TCP Connection Capacity
Use Section 5.2 of [RFC3511] unmodified.
8.2. Maximum TCP Connection Establishment Rate
Use Section 5.3 of [RFC3511] unmodified.
9. DNS Resolution Performance
This section describes benchmarking tests dedicated to DNS64 (see
[RFC6147]), used as DNS support for single-translation technologies
such as NAT64.
9.1. Test and Traffic Setup
The test setup in Figure 3 follows the setup proposed for single-
translation IPv6 transition technologies in Figure 1.
1:AAAA query +--------------------+
+------------| |<-------------+
| |IPv6 Tester IPv4| |
| +-------->| |----------+ |
| | +--------------------+ 3:empty | |
| | 6:synt'd AAAA, | |
| | AAAA +--------------------+ 5:valid A| |
| +---------| |<---------+ |
| |IPv6 DUT IPv4| |
+----------->| (DNS64) |--------------+
+--------------------+ 2:AAAA query, 4:A query
Figure 3: Test Setup 3 (DNS64)
The test traffic SHOULD follow be composed of the steps below. following messages.
1. Query for the AAAA record of a domain name (from client to DNS64
server)
2. Query for the AAAA record of the same domain name (from DNS64
server to authoritative DNS server)
3. Empty AAAA record answer (from authoritative DNS server to DNS64
server)
4. Query for the A record of the same domain name (from DNS64 server
to authoritative DNS server)
5. Valid A record answer (from authoritative DNS server to DNS64
server)
6. Synthesized AAAA record answer (from DNS64 server to client)
The Tester plays the role of DNS client as well as authoritative DNS
server. It MAY be realized as a single physical device, or
alternatively, two physical devices MAY be used.
Please note that:
o If the DNS64 server implements caching and there is a cache hit,
then step 1 is followed by step 6 (and steps 2 through 5 are
omitted).
o If the domain name has a AAAA record, then it is returned in step
3 by the authoritative DNS server, steps 4 and 5 are omitted, and
the DNS64 server does not synthesize a AAAA record but returns the
received AAAA record to the client.
o As for the IP version used between the Tester and the DUT, IPv6
MUST be used between the client and the DNS64 server (as a DNS64
server provides service for an IPv6-only client), but either IPv4
or IPv6 MAY be used between the DNS64 server and the authoritative
DNS server.
9.2. Benchmarking DNS Resolution Performance
Objective: To determine DNS64 performance by means of the maximum
number of successfully processed DNS requests per second.
Procedure: Send a specific number of DNS queries at a specific rate
to the DUT, and then count the replies from the DUT that are received
in time (within a predefined timeout period from the sending time of
the corresponding query, having the default value 1 second) and that
are valid (contain a AAAA record). If the count of sent queries is
equal to the count of received replies, the rate of the queries is
raised, and the test is rerun. If fewer replies are received than
queries were sent, the rate of the queries is reduced, and the test
is rerun. The duration of each trial SHOULD be at least 60 seconds.
This will reduce the potential gain of a DNS64 server, which is able
to exhibit higher performance by storing the requests and thus also
utilizing the timeout time for answering them. For the same reason,
no higher timeout time than 1 second SHOULD be used. For further
considerations, see [Lencse1].
The maximum number of processed DNS queries per second is the fastest
rate at which the count of DNS replies sent by the DUT is equal to
the number of DNS queries sent to it by the test equipment.
The test SHOULD be repeated at least 20 times, and the median and
1st/99th percentiles of the number of processed DNS queries per
second SHOULD be calculated.
Details and parameters:
1. Caching
First, all the DNS queries MUST contain different domain names
(or domain names MUST NOT be repeated before the cache of the DUT
is exhausted). Then, new tests MAY be executed with when domain
names, names
are 20%, 40%, 60%, 80%, and 100% of which are cached. We note Ensuring that ensuring a record being
is cached requires repeating it a domain name both "late enough"
after the first query to be already resolved and be present in
the cache and "early enough" to be still present in the cache.
2. Existence of a AAAA record
First, all the DNS queries MUST contain domain names that do not
have a AAAA record and have exactly one A record. Then, new
tests MAY be executed with domain names, when 20%, 40%, 60%, 80%, and 100% of which domain
names have a AAAA record.
Please note that the two conditions above are orthogonal; thus, all
their combinations are possible and MAY be tested. The testing with
0% cached domain names and with 0% existing AAAA records is REQUIRED,
and the other combinations are OPTIONAL. (When all the domain names
are cached, then the results do not depend on what percentage of the
domain names have AAAA records; thus, these combinations are not
worth testing one by one.)
Reporting format: The primary result of the DNS64 test is the median
of the number of processed DNS queries per second measured with the
above mentioned "0% + 0% combination". The median SHOULD be
complemented with the 1st and 99th percentiles to show the stability
of the result. If optional tests are done, the median and the 1st
and 99th percentiles MAY be presented in a two-dimensional table
where the dimensions are the proportion of the repeated domain names
and the proportion of the DNS names having AAAA records. The two
table headings SHOULD contain these percentage values.
Alternatively, the results MAY be presented as a corresponding two-
dimensional graph. In this case, the graph SHOULD show the median
values with the percentiles as error bars. From both the table and
the graph, one-dimensional excerpts MAY be made at any given fixed-
percentage value of the other dimension. In this case, the fixed
value MUST be given together with a one-dimensional table or graph.
9.2.1. Requirements for the Tester
Before a Tester can be used for testing a DUT at rate r queries per
second with t seconds timeout, it MUST perform a self-test in order
to exclude the possibility that the poor performance of the Tester
itself influences the results. To perform a self-test, the Tester is
looped back (leaving out DUT), and its authoritative DNS server
subsystem is configured to be able to answer all the AAAA record
queries. To pass the self-test, the Tester SHOULD be able to answer
AAAA record queries at rate of 2*(r+delta) within a 0.25*t timeout,
where the value of delta is at least 0.1.
Explanation: When performing DNS64 testing, each AAAA record query
may result in at most two queries sent by the DUT: the first for a
AAAA record and the second for an A record (they are both sent when
there is no cache hit and also no AAAA record exists). The
parameters above guarantee that the authoritative DNS server
subsystem of the DUT is able to answer the queries at the required
frequency using up not more than half of the timeout time.
Note: A sample open-source test program, dns64perf++, is available
from [Dns64perf] and is documented in [Lencse2]. It implements only
the client part of the Tester and should be used together with an
authoritative DNS server implementation, e.g., BIND, NSD, or YADIFA.
Its experimental extension for testing caching is available from
[Lencse3] and is documented in [Lencse4].
10. Overload Scalability
Scalability has been often discussed; however, in the context of
network devices, a formal definition or a measurement method has not
yet been proposed. In this context, we can define overload
scalability as the ability of each transition technology to
accommodate network growth. Poor scalability usually leads to poor
performance. Considering this, overload scalability can be measured
by quantifying the network performance degradation associated with an
increased number of network flows.
The following subsections describe how the test setups can be
modified to create network growth and how the associated performance
degradation can be quantified.
10.1. Test Setup
The test setups defined in Section 4 have to be modified to create
network growth.
10.1.1. Single-Translation Transition Technologies
In the case of single-translation transition technologies, the
network growth can be generated by increasing the number of network
flows (NFs) generated by the Tester machine (see Figure 4).
+-------------------------+
+------------|NF1 NF1|<-------------+
| +---------|NF2 Tester NF2|<----------+ |
| | ...| | | |
| | +-----|NFn NFn|<------+ | |
| | | +-------------------------+ | | |
| | | | | |
| | | +-------------------------+ | | |
| | +---->|NFn NFn|-------+ | |
| | ...| DUT | | |
| +-------->|NF2 (translator) NF2|-----------+ |
+----------->|NF1 NF1|--------------+
+-------------------------+
Figure 4: Test Setup 4 (Single DUT with Increased
Network Flows)
10.1.2. Encapsulation and Double-Translation Transition Technologies
Similarly, for the encapsulation and double-translation transition
technologies, a multi-flow setup is recommended. Considering a
multipoint-to-point scenario, for most transition technologies, one
of the edge nodes is designed to support more than one connecting
device. Hence, the recommended test setup is an n:1 design, where n
is the number of client DUTs connected to the same server DUT (see
Figure 5).
+-------------------------+
+--------------------|NF1 NF1|<--------------+
| +-----------------|NF2 Tester NF2|<-----------+ |
| | ...| | | |
| | +-------------|NFn NFn|<-------+ | |
| | | +-------------------------+ | | |
| | | | | |
| | | +-----------------+ +---------------+ | | |
| | +--->| NFn DUT n NFn |--->|NFn NFn| ---+ | |
| | +-----------------+ | | | |
| | ... | | | |
| | +-----------------+ | DUT n+1 | | |
| +------->| NF2 DUT 2 NF2 |--->|NF2 NF2|--------+ |
| +-----------------+ | | |
| +-----------------+ | | |
+---------->| NF1 DUT 1 NF1 |--->|NF1 NF1|-----------+
+-----------------+ +---------------+
Figure 5: Test Setup 5 (DUAL DUT with Increased
Network Flows)
This test setup can help to quantify the scalability of the server
device. However, for testing the overload scalability of the client
DUTs, additional recommendations are needed.
For encapsulation transition technologies, an m:n setup can be
created, where m is the number of flows applied to the same client
device and n the number of client devices connected to the same
server device.
For translation-based transition technologies, the client devices can
be separately tested with n network flows using the test setup
presented in Figure 4.
10.2. Benchmarking Performance Degradation
10.2.1. Network Performance Degradation with Simultaneous Load
Objective: To quantify the performance degradation introduced by n
parallel and simultaneous network flows.
Procedure: First, the benchmarking tests presented in Section 7 have
to be performed for one network flow.
The same tests have to be repeated for n network flows, where the
network flows are started simultaneously. The performance
degradation of the X benchmarking dimension SHOULD be calculated as
relative performance change between the 1-flow (single flow) results
and the n-flow results, using the following formula:
Xn - X1
Xpd = ----------- * 100, where: X1 = result for 1-flow
X1 Xn = result for n-flows
This formula SHOULD be applied only for "lower is better" benchmarks
(e.g., latency). For "higher is better" benchmarks (e.g.,
throughput), the following formula is RECOMMENDED:
X1 - Xn
Xpd = ----------- * 100, where: X1 = result for 1-flow
X1 Xn = result for n-flows
As a guideline for the maximum number of flows n, the value can be
deduced by measuring the Concurrent TCP Connection Capacity as
described by [RFC3511], following the test setups specified by
Section 4.
Reporting Format: The performance degradation SHOULD be expressed as
a percentage. The number of tested parallel flows n MUST be clearly
specified. For each of the performed benchmarking tests, there
SHOULD be a table containing a column for each frame size. The table
SHOULD also state the applied frame rate. In the case of benchmarks
for which more than one value is reported (e.g., IPDV, discussed in
Section 7.3.2), a column for each of the values SHOULD be included.
10.2.2. Network Performance Degradation with Incremental Load
Objective: To quantify the performance degradation introduced by n
parallel and incrementally started network flows.
Procedure: First, the benchmarking tests presented in Section 7 have
to be performed for one network flow.
The same tests have to be repeated for n network flows, where the
network flows are started incrementally in succession, each after
time t. In other words, if flow i is started at time x, flow i+1
will be started at time x+t. Considering the time t, the time
duration of each iteration must be extended with the time necessary
to start all the flows, namely, (n-1)xt. The measurement for the
first flow SHOULD be at least 60 seconds in duration.
The performance degradation of the x benchmarking dimension SHOULD be
calculated as relative performance change between the 1-flow results
and the n-flow results, using the formula presented in
Section 10.2.1. Intermediary degradation points for 1/4*n, 1/2*n,
and 3/4*n MAY also be performed.
Reporting Format: The performance degradation SHOULD be expressed as
a percentage. The number of tested parallel flows n MUST be clearly
specified. For each of the performed benchmarking tests, there
SHOULD be a table containing a column for each frame size. The table
SHOULD also state the applied frame rate and time duration T, which
is used as
increment an incremental step between the network flows. The units
of measurement for T SHOULD be seconds. A column for the
intermediary degradation points MAY also be displayed. In the case
of benchmarks for which more than one value is reported (e.g., IPDV,
discussed in Section 7.3.2), a column for each of the values SHOULD
be included.
11. NAT44 and NAT66
Although these technologies are not the primary scope of this
document, the benchmarking methodology associated with single-
translation technologies as defined in Section 4.1 can be employed to
benchmark implementations that use NAT44 (as defined by [RFC2663]
with the behavior described by [RFC7857]) and implementations that
use NAT66 (as defined by [RFC6296]).
12. Summarizing Function and Variation
To ensure the stability of the benchmarking scores obtained using the
tests presented in Sections 7 through 9, multiple test iterations are
RECOMMENDED. Using a summarizing function (or measure of central
tendency) can be a simple and effective way to compare the results
obtained across different iterations. However, over-summarization is
an unwanted effect of reporting a single number.
Measuring the variation (dispersion index) can be used to counter the
over-summarization effect. Empirical data obtained following the
proposed methodology can also offer insights on which summarizing
function would fit better.
To that end, data presented in [ietf95pres] indicate the median as a
suitable summarizing function and the 1st and 99th percentiles as
variation measures for DNS Resolution Performance and PDV. The
median and percentile calculation functions SHOULD follow the
recommendations of Section 11.3 of [RFC2330].
For a fine-grained analysis of the frequency distribution of the
data, histograms or cumulative distribution function plots can be
employed.
13. Security Considerations
Benchmarking activities as described in this memo are limited to
technology characterization using controlled stimuli in a laboratory
environment, with dedicated address space and the constraints
specified in the sections above.
The benchmarking network topology will be an independent test setup
and MUST NOT be connected to devices that may forward the test
traffic into a production network or misroute traffic to the test
management network.
Further, benchmarking is performed on a "black-box" basis, relying
solely on measurements observable external to the DUT or System Under
Test (SUT). Special capabilities SHOULD NOT exist in the DUT/SUT
specifically for benchmarking purposes. Any implications for network
security arising from the DUT/SUT SHOULD be identical in the lab and
in production networks.
14. IANA Considerations
The IANA has allocated the prefix 2001:2::/48 [RFC5180] for IPv6
benchmarking. For IPv4 benchmarking, the 198.18.0.0/15 prefix was
reserved, as described in [RFC6890]. The two ranges are sufficient
for benchmarking IPv6 transition technologies. Thus, no action is
requested.
15. References
15.1. Normative References
[RFC1242] Bradner, S., "Benchmarking Terminology for Network
Interconnection Devices", RFC 1242, DOI 10.17487/RFC1242,
July 1991, <http://www.rfc-editor.org/info/rfc1242>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC2330] Paxson, V., Almes, G., Mahdavi, J., and M. Mathis,
"Framework for IP Performance Metrics", RFC 2330,
DOI 10.17487/RFC2330, May 1998,
<http://www.rfc-editor.org/info/rfc2330>.
[RFC2544] Bradner, S. and J. McQuaid, "Benchmarking Methodology for
Network Interconnect Devices", RFC 2544,
DOI 10.17487/RFC2544, March 1999,
<http://www.rfc-editor.org/info/rfc2544>.
[RFC3393] Demichelis, C. and P. Chimento, "IP Packet Delay Variation
Metric for IP Performance Metrics (IPPM)", RFC 3393,
DOI 10.17487/RFC3393, November 2002,
<http://www.rfc-editor.org/info/rfc3393>.
[RFC3511] Hickman, B., Newman, D., Tadjudin, S., and T. Martin,
"Benchmarking Methodology for Firewall Performance",
RFC 3511, DOI 10.17487/RFC3511, April 2003,
<http://www.rfc-editor.org/info/rfc3511>.
[RFC5180] Popoviciu, C., Hamza, A., Van de Velde, G., and D.
Dugatkin, "IPv6 Benchmarking Methodology for Network
Interconnect Devices", RFC 5180, DOI 10.17487/RFC5180,
May 2008, <http://www.rfc-editor.org/info/rfc5180>.
[RFC5481] Morton, A. and B. Claise, "Packet Delay Variation
Applicability Statement", RFC 5481, DOI 10.17487/RFC5481,
March 2009, <http://www.rfc-editor.org/info/rfc5481>.
[RFC6201] Asati, R., Pignataro, C., Calabria, F., and C. Olvera,
"Device Reset Characterization", RFC 6201,
DOI 10.17487/RFC6201, March 2011,
<http://www.rfc-editor.org/info/rfc6201>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <http://www.rfc-editor.org/info/rfc8174>.
15.2. Informative References
[RFC2663] Srisuresh, P. and M. Holdrege, "IP Network Address
Translator (NAT) Terminology and Considerations",
RFC 2663, DOI 10.17487/RFC2663, August 1999,
<http://www.rfc-editor.org/info/rfc2663>.
[RFC4213] Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms
for IPv6 Hosts and Routers", RFC 4213,
DOI 10.17487/RFC4213, October 2005,
<http://www.rfc-editor.org/info/rfc4213>.
[RFC4659] De Clercq, J., Ooms, D., Carugi, M., and F. Le Faucheur,
"BGP-MPLS IP Virtual Private Network (VPN) Extension for
IPv6 VPN", RFC 4659, DOI 10.17487/RFC4659, September 2006,
<http://www.rfc-editor.org/info/rfc4659>.
[RFC4798] De Clercq, J., Ooms, D., Prevost, S., and F. Le Faucheur,
"Connecting IPv6 Islands over IPv4 MPLS Using IPv6
Provider Edge Routers (6PE)", RFC 4798,
DOI 10.17487/RFC4798, February 2007,
<http://www.rfc-editor.org/info/rfc4798>.
[RFC5569] Despres, R., "IPv6 Rapid Deployment on IPv4
Infrastructures (6rd)", RFC 5569, DOI 10.17487/RFC5569,
January 2010, <http://www.rfc-editor.org/info/rfc5569>.
[RFC6144] Baker, F., Li, X., Bao, C., and K. Yin, "Framework for
IPv4/IPv6 Translation", RFC 6144, DOI 10.17487/RFC6144,
April 2011, <http://www.rfc-editor.org/info/rfc6144>.
[RFC6146] Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful
NAT64: Network Address and Protocol Translation from IPv6
Clients to IPv4 Servers", RFC 6146, DOI 10.17487/RFC6146,
April 2011, <http://www.rfc-editor.org/info/rfc6146>.
[RFC6147] Bagnulo, M., Sullivan, A., Matthews, P., and I. van
Beijnum, "DNS64: DNS Extensions for Network Address
Translation from IPv6 Clients to IPv4 Servers", RFC 6147,
DOI 10.17487/RFC6147, April 2011,
<http://www.rfc-editor.org/info/rfc6147>.
[RFC6219] Li, X., Bao, C., Chen, M., Zhang, H., and J. Wu, "The
China Education and Research Network (CERNET) IVI
Translation Design and Deployment for the IPv4/IPv6
Coexistence and Transition", RFC 6219,
DOI 10.17487/RFC6219, May 2011,
<http://www.rfc-editor.org/info/rfc6219>.
[RFC6296] Wasserman, M. and F. Baker, "IPv6-to-IPv6 Network Prefix
Translation", RFC 6296, DOI 10.17487/RFC6296, June 2011,
<http://www.rfc-editor.org/info/rfc6296>.
[RFC6333] Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual-
Stack Lite Broadband Deployments Following IPv4
Exhaustion", RFC 6333, DOI 10.17487/RFC6333, August 2011,
<http://www.rfc-editor.org/info/rfc6333>.
[RFC6877] Mawatari, M., Kawashima, M., and C. Byrne, "464XLAT:
Combination of Stateful and Stateless Translation",
RFC 6877, DOI 10.17487/RFC6877, April 2013,
<http://www.rfc-editor.org/info/rfc6877>.
[RFC6890] Cotton, M., Vegoda, L., Bonica, R., Ed., and B. Haberman,
"Special-Purpose IP Address Registries", BCP 153,
RFC 6890, DOI 10.17487/RFC6890, April 2013,
<http://www.rfc-editor.org/info/rfc6890>.
[RFC7596] Cui, Y., Sun, Q., Boucadair, M., Tsou, T., Lee, Y., and I.
Farrer, "Lightweight 4over6: An Extension to the Dual-
Stack Lite Architecture", RFC 7596, DOI 10.17487/RFC7596,
July 2015, <http://www.rfc-editor.org/info/rfc7596>.
[RFC7597] Troan, O., Ed., Dec, W., Li, X., Bao, C., Matsushima, S.,
Murakami, T., and T. Taylor, Ed., "Mapping of Address and
Port with Encapsulation (MAP-E)", RFC 7597,
DOI 10.17487/RFC7597, July 2015,
<http://www.rfc-editor.org/info/rfc7597>.
[RFC7599] Li, X., Bao, C., Dec, W., Ed., Troan, O., Matsushima, S.,
and T. Murakami, "Mapping of Address and Port using
Translation (MAP-T)", RFC 7599, DOI 10.17487/RFC7599, July
2015, <http://www.rfc-editor.org/info/rfc7599>.
[RFC7857] Penno, R., Perreault, S., Boucadair, M., Ed., Sivakumar,
S., and K. Naito, "Updates to Network Address Translation
(NAT) Behavioral Requirements", BCP 127, RFC 7857,
DOI 10.17487/RFC7857, April 2016,
<http://www.rfc-editor.org/info/rfc7857>.
[RFC7915] Bao, C., Li, X., Baker, F., Anderson, T., and F. Gont,
"IP/ICMP Translation Algorithm", RFC 7915,
DOI 10.17487/RFC7915, June 2016,
<http://www.rfc-editor.org/info/rfc7915>.
[Dns64perf]
Bakai, D., "A C++11 DNS64 performance tester",
<https://github.com/bakaid/dns64perfpp>.
[ietf95pres]
Georgescu, M., "Benchmarking Methodology for IPv6
Transition Technologies", IETF 95 Proceedings, Buenos
Aires, Argentina, April 2016,
<https://www.ietf.org/proceedings/95/slides/
slides-95-bmwg-2.pdf>.
[Lencse1] Lencse, G., Georgescu, M., and Y. Kadobayashi,
"Benchmarking Methodology for DNS64 Servers", Computer
Communications, vol. 109, no. 1, pp. 162-175,
DOI 10.1016/j.comcom.2017.06.004, September 2017,
<http://www.sciencedirect.com/science/article/pii/
S0140366416305904?via%3Dihub>
[Lencse2] Lencse, G. and D. Bakai, "Design and Implementation of a
Test Program for Benchmarking DNS64 Servers", IEICE
Transactions on Communications, Vol. E100-B, No. 6,
pp. 948-954, DOI 10.1587/transcom.2016EBN0007, June 2017,
<https://www.jstage.jst.go.jp/article/transcom/E100.B/
6/E100.B_2016EBN0007/_article>.
[Lencse3] dns64perfppc,
<http://www.hit.bme.hu/~lencse/dns64perfppc/>.
[Lencse4] Lencse, G., "Enabling Dns64perf++ for Benchmarking the
Caching Performance of DNS64 Servers", unpublished, review
version, <http://www.hit.bme.hu/~lencse/publications/
IEICE-2016-dns64perfppc-for-review.pdf>.
[IEEE802.1AC]
IEEE, "IEEE Standard for Local and metropolitan area
networks -- Media Access Control (MAC) Service
Definition", IEEE 802.1AC.
[IEEE802.1Q]
IEEE, "IEEE Standard for Local and metropolitan area
networks -- Bridges and Bridged Networks", IEEE Std
802.1Q.
Appendix A. Theoretical Maximum Frame Rates
This appendix describes the recommended calculation formulas for the
theoretical maximum frame rates to be employed over Ethernet as
example media. The formula takes into account the frame size
overhead created by the encapsulation or translation process. For
example, the 6in4 encapsulation described in [RFC4213] adds 20 bytes
of overhead to each frame.
Considering X to be the frame size and O to be the frame size
overhead created by the encapsulation or translation process, the
maximum theoretical frame rate for Ethernet can be calculated using
the following formula:
Line Rate (bps)
------------------------------------
(8 bits/byte) * (X+O+20) bytes/frame
The calculation is based on the formula recommended by [RFC5180] in
Appendix A.1. As an example, the frame rate recommended for testing
a 6in4 implementation over 10 Mb/s Ethernet with 64 bytes frames is:
10,000,000 (bps)
-------------------------------------- = 12,019 fps
(8 bits/byte) * (64+20+20) bytes/frame
The complete list of recommended frame rates for 6in4 encapsulation
can be found in the following table:
+------------+---------+----------+-----------+------------+
| Frame size | 10 Mb/s | 100 Mb/s | 1000 Mb/s | 10000 Mb/s |
| (bytes) | (fps) | (fps) | (fps) | (fps) |
+------------+---------+----------+-----------+------------+
| 64 | 12,019 | 120,192 | 1,201,923 | 12,019,231 |
| 128 | 7,440 | 74,405 | 744,048 | 7,440,476 |
| 256 | 4,223 | 42,230 | 422,297 | 4,222,973 |
| 512 | 2,264 | 22,645 | 226,449 | 2,264,493 |
| 678 | 1,740 | 17,409 | 174,094 | 1,740,947 |
| 1024 | 1,175 | 11,748 | 117,481 | 1,174,812 |
| 1280 | 947 | 9,470 | 94,697 | 946,970 |
| 1518 | 802 | 8,023 | 80,231 | 802,311 |
| 1522 | 800 | 8,003 | 80,026 | 800,256 |
| 2048 | 599 | 5,987 | 59,866 | 598,659 |
| 4096 | 302 | 3,022 | 30,222 | 302,224 |
| 8192 | 152 | 1,518 | 15,185 | 151,846 |
| 9216 | 135 | 1,350 | 13,505 | 135,048 |
+------------+---------+----------+-----------+------------+
Acknowledgements
The authors thank Youki Kadobayashi and Hiroaki Hazeyama for their
constant feedback and support. The thanks should be extended to the
NECOMA project members for their continuous support. We thank
Emanuel Popa, Ionut Spirlea, and the RCS&RDS IP/MPLS Backbone Team
for their support and insights. We thank Scott Bradner for the
useful suggestions and note that portions of text from Scott's
documents were used in this memo (e.g., the "Latency" section). A
big thank you to Al Morton and Fred Baker for their detailed review
of the document and very helpful suggestions. Other helpful comments
and suggestions were offered by Bhuvaneswaran Vengainathan, Andrew
McGregor, Nalini Elkins, Kaname Nishizuka, Yasuhiro Ohara, Masataka
Mawatari, Kostas Pentikousis, Bela Almasi, Tim Chown, Paul Emmerich,
and Stenio Fernandes. A special thank you to the RFC Editor Team for
their thorough editorial review and helpful suggestions.
Authors' Addresses
Marius Georgescu
RCS&RDS
Strada Dr. Nicolae D. Staicovici 71-75
Bucharest 030167
Romania
Phone: +40 31 005 0979
Email: marius.georgescu@rcs-rds.ro
Liviu Pislaru
RCS&RDS
Strada Dr. Nicolae D. Staicovici 71-75
Bucharest 030167
Romania
Phone: +40 31 005 0979
Email: liviu.pislaru@rcs-rds.ro
Gabor Lencse
Szechenyi Istvan University
Egyetem ter 1.
Gyor
Hungary
Phone: +36 20 775 8267
Email: lencse@sze.hu