Internet DRAFT - draft-elkins-ippm-pdm-nn
draft-elkins-ippm-pdm-nn
INTERNET-DRAFT N. Elkins
B. Jouris
Intended Status: Informational Inside Products
Expires: September 30, 2017 March 29, 2017
Using PDM to Monitor Net Neutrality
draft-elkins-ippm-pdm-nn-00
Abstract
Monitoring of net neutrality is of interest to regulators as well as
users throughout the world. Standardized metrics are lacking.
Measurements need to be at the end user client, be able to accurately
separate wire and host time, detect quality of service provided to
individual applications and be lightweight. The IPv6 Performance and
Diagnostic Metrics (PDM) Destination Option meets all these criteria.
We propose that PDM be used for such measurements. A gap analysis
shows that PDM is available for IPv6 only and not for IPv4 or low
powered devices.
Status of this Memo
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Copyright and License Notice
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Table of Contents
1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 What Measurements Does PDM Provide? . . . . . . . . . . . . 3
1.2 How Does PDM Provide This Information? . . . . . . . . . . . 3
1.3 Definitions of Round-Trip Delay and Server Delay . . . . . . 4
1.4 How Will PDM Be Used to Measure Net Neutrality? . . . . . . 4
2 Advantages of PDM . . . . . . . . . . . . . . . . . . . . . . . 4
2.1 Advantages of PDM for Measurement . . . . . . . . . . . . . 4
2.2 Advantage of PDM for Scaleability . . . . . . . . . . . . . 5
2.3 Isolating Wire Time Accurately . . . . . . . . . . . . . . . 5
2.4 Measurement of the Application . . . . . . . . . . . . . . . 5
2.5 Calculation of speed . . . . . . . . . . . . . . . . . . . . 6
2.6 Lightweight measurement technique . . . . . . . . . . . . . 6
2.7 Universal Measurement Technique . . . . . . . . . . . . . . 6
3 Gap Analysis of PDM in Net Neutrality Measurements . . . . . . . 7
3.1 PDM for IPv4 . . . . . . . . . . . . . . . . . . . . . . . . 7
3.2 PDM for Low Powered Devices . . . . . . . . . . . . . . . . 7
4 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
5 Security Considerations . . . . . . . . . . . . . . . . . . . . 7
6 References . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
6.1 Normative References . . . . . . . . . . . . . . . . . . . . 7
6.2 Informative References . . . . . . . . . . . . . . . . . . . 7
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
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1 Background
The question of whether one is actually getting the wire speed that
one is paying for is complex. In [NNRequire], European regulators
make the use case: "The European Regulation requires internet service
providers (ISPs) to specify new speed values for example minimum,
maximum, and normally available speeds in fixed network. The
measurement use case is to assess if these contractual speed values
are met. The problem is to define measurements that can be run by
end-users and is accurate enough to have legal value."
A number of factors enter into measuring such time:
1. Measurement which resides at the end-user client
2. Separating wire time from the application / stack time
3. Accuracy of measurement
The hybrid measurement technique, IPv6 PDM defined in [PDM] embeds
timing information in each packet. Such values may be used to
estimate QoS as experienced by an end user device. PDM also provides
the ability to determine quickly if the (latency) problem is in the
network or in the server (application).
1.1 What Measurements Does PDM Provide?
PDM provides:
1. Round-trip delay (wire time)
2. Server delay (host time)
1.2 How Does PDM Provide This Information?
From [PDM], Section 2: Measurement Information Derived from PDM
"Each packet contains information about the sender and receiver. In
IP protocol, the identifying information is called a "5-tuple".
The 5-tuple consists of:
SADDR : IP address of the sender
SPORT : Port for sender
DADDR : IP address of the destination
DPORT : Port for destination
PROTC : Protocol for upper layer (ex. TCP, UDP, ICMP, etc.)
The PDM contains the following base fields:
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PSNTP : Packet Sequence Number This Packet
PSNLR : Packet Sequence Number Last Received
DELTATLR : Delta Time Last Received
DELTATLS : Delta Time Last Sent"
This information, combined with the 5-tuple, allows the measurement
of round-trip delay (wire time) and server delay (host time).
1.3 Definitions of Round-Trip Delay and Server Delay
The PDM description defines the measurement fields of interest.
From PDM [PDM]:
"Round-trip *Network* delay is the delay for packet transfer from a
source host to a destination host and then back to the source host.
This measurement has been defined, and the advantages and
disadvantages discussed in "A Round-trip Delay Metric for IPPM"
[RFC2681]."
"Server delay is the interval between when a packet is received by a
device and the first corresponding packet is sent back in response.
This may be "Server Processing Time". It may also be a delay caused
by acknowledgements. Server processing time includes the time taken
by the combination of the stack and application to return the
response. The stack delay may be related to network performance. If
this aggregate time is seen as a problem, and there is a need to make
a clear distinction between application processing time and stack
delay, including that caused by the network, then more client based
measurements are needed."
1.4 How Will PDM Be Used to Measure Net Neutrality?
Since PDM is embedded in the packet, any measuring tool that is able
to capture packets may serve as a capture point. Such devices range
from a simple Wireshark packet capture to a large network of agents
and controllers using the LMAP [RFC7594] protocol.
2 Advantages of PDM
2.1 Advantages of PDM for Measurement
From [PDM]
"Advantages include:
1. Real measure of actual transactions.
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2. Independence from transport layer protocols.
3. Ability to span organizational boundaries with consistent
instrumentation.
4. No time synchronization needed between session partners
5. Ability to handle all transport protocols (TCP, UDP, SCTP, etc) in
a uniform way "
2.2 Advantage of PDM for Scaleability
The advantage of PDM in scaleability for measuring net neutrality is
that no additional client software needs to be implemented. The task
of having some agent at each client that one wishes to measure
throughout the world is nothing less than daunting. Having said
that, some organizations, for example, with the RIPE probes, have
undertaken this task with quite a bit of success.
Imagine how much simpler this might be if nothing needed to be
installed at the client -- if the actual data needed for accurate
measurement was in the packet itself. This is what PDM provides.
2.3 Isolating Wire Time Accurately
From [NNRequire], one of the requirements of net neutrality is to
isolate the wire time from other factors:
"When measurement tasks are run by an end-user, end-user environment
specific factors like cross-traffic, measurement interface
(fixed/wireless), firewalls, client operating system and hardware
can influence the measurement result. These factors have to be
detected and taken into account when assessing measurements
performed by end-users."
PDM is implemented as close to the network interface as possible so
the isolation of wire time is expected to be quite accurate.
2.4 Measurement of the Application
PDM is embedded in each packet. Each packet inherently has a 5-
tuple. So, as the packet is captured and analyzed via analysis
tools, data on application usage is available.
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2.5 Calculation of speed
One of the requirements from [NNRequire] states that "speed should be
calculated based on IP packet payload". Since PDM is embedded in the
packet, and packets are being captured by the measurement device, the
length of the IP and upper layer headers are readily differentiated
from the size of the actual payload.
2.6 Lightweight measurement technique
Another of the requirements of [NNRequire] states that "measurement
does not block the internet access usage for whole day and does not
generate excessive network load."
PDM is embedded in the packet and so clearly does not block usage of
the Internet for the end-user for any task required.
As far as load, from [PDM], Appendix C: Potential Overhead
Considerations, discusses the additional overhead created by adding
PDM to a packet.
"Below is a table outlining the potential overhead in terms of
additional time to deliver the response to the end user for various
assumed RTTs.
Bytes RTT Bytes Bytes New Overhead
in Packet Per Millisec in PDM RTT
=====================================================================
1000 1000 milli 1 16 1016.000 16.000 milli
1000 100 milli 10 16 101.600 1.600 milli
1000 10 milli 100 16 10.160 .160 milli
1000 1 milli 1000 16 1.016 .016 milli
Below are some examples of actual RTTs for packets traversing large
enterprise networks.
Bytes RTT Bytes Bytes New Overhead
in Packet Per Millisec in PDM RTT
=====================================================================
1000 17 milli 58 16 17.360 .360 milli
2.7 Universal Measurement Technique
[NNRequire] would like technique which is universal. That is:
"In principle, any solution should be equally applicable to both
fixed and mobile Internet access services from narrow band to multi-
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gigabit connections."
PDM is embedded in the IP packet. The operating system merely needs
to implement it. PDM has no favorites: fixed or mobile are as one to
it.
3 Gap Analysis of PDM in Net Neutrality Measurements
3.1 PDM for IPv4
Much as we might want the world to use IPv6 exclusively, the thorny
issue of a world wide base of IPv4 on the Internet which refuses to
die quietly remains. Today, PDM is able to measure IPv6 only. PDM
needs to be extended to measure IPv4.
3.2 PDM for Low Powered Devices
The world is becoming filled with small, somewhat intelligent devices
which communicate across networks. Should net neutrality be
extended to such devices, then PDM will need to be defined for low
powered devices. Having said that, the overhead created by PDM,
though inconsequential for laptops and cell phones, may be too much
for very small devices.
4 IANA Considerations
There are no IANA considerations.
5 Security Considerations
Security considerations for PDM are detailed in the PDM [PDM]
description.
6 References
6.1 Normative References
[RFC2681] Almes, G., Kalidindi, S., and M. Zekauskas, "A Round-trip
Delay Metric for IPPM", RFC 2681, September 1999.
[RFC7594] Eardley, P., "A Framework for Large-Scale Measurement of
Broadband Performance (LMAP)", RFC 7594, October, 2015.
6.2 Informative References
[PDM] Elkins, N. "IPv6 Performance and Diagnostic Metrics (PDM)
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Destination Option", draft-ietf-ippm-6man-pdm-option-09, March, 2017
[Work in Progress]
[NNRequire] Nieminen, K., "Net Neutrality Measurements: Regulatory
Use Case and Problem Statement", draft-nieminen-ippm-nn-measurements-
00, February, 2017 [Work in Progress]
Acknowledgments
Authors' Addresses
Nalini Elkins
Inside Products, Inc.
36A Upper Circle
Carmel Valley, CA 93924
United States
Phone: +1 831 659 8360
Email: nalini.elkins@insidethestack.com
http://www.insidethestack.com
William Jouris
Inside Products, Inc.
36A Upper Circle
Carmel Valley, CA 93924
United States
Phone: +1 831 659 8360
Email: bill.jouris@insidethestack.com
http://www.insidethestack.com
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