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 This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/1id-abstracts.html The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html Elkins Expires September 30, 2017 [Page 1] INTERNET DRAFT elkins-ippm-pdm-nn-00 March 29, 2017 Copyright and License Notice Copyright (c) 2017 IETF Trust and the persons identified as the document authors. All rights reserved. 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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 Elkins Expires September 30, 2017 [Page 2] INTERNET DRAFT elkins-ippm-pdm-nn-00 March 29, 2017 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: Elkins Expires September 30, 2017 [Page 3] INTERNET DRAFT elkins-ippm-pdm-nn-00 March 29, 2017 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. Elkins Expires September 30, 2017 [Page 4] INTERNET DRAFT elkins-ippm-pdm-nn-00 March 29, 2017 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. Elkins Expires September 30, 2017 [Page 5] INTERNET DRAFT elkins-ippm-pdm-nn-00 March 29, 2017 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- Elkins Expires September 30, 2017 [Page 6] INTERNET DRAFT elkins-ippm-pdm-nn-00 March 29, 2017 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) Elkins Expires September 30, 2017 [Page 7] INTERNET DRAFT elkins-ippm-pdm-nn-00 March 29, 2017 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 Elkins Expires September 30, 2017 [Page 8]