--- 1/draft-ietf-ippm-2330-ipv6-00.txt 2017-03-06 00:13:46.005567987 -0800 +++ 2/draft-ietf-ippm-2330-ipv6-01.txt 2017-03-06 00:13:46.037568758 -0800 @@ -1,38 +1,37 @@ Network Working Group A. Morton Internet-Draft AT&T Labs Updates: 2330 (if approved) J. Fabini Intended status: Informational TU Wien -Expires: January 5, 2017 N. Elkins +Expires: September 7, 2017 N. Elkins Inside Products, Inc. M. Ackermann Blue Cross Blue Shield of Michigan V. Hegde Consultant - July 04, 2016 + March 6, 2017 IPv6 Updates for IPPM's Active Metric Framework - draft-ietf-ippm-2330-ipv6-00 + draft-ietf-ippm-2330-ipv6-01 Abstract This memo updates the IP Performance Metrics (IPPM) Framework RFC 2330 with new considerations for measurement methodology and testing. - The memo updates the definition of standard-formed packets in RFC - 2330 to include IPv6 packets. It also augments distinguishing - aspects of packets, referred to as Type-P for test packets in RFC - 2330. - - Two points (at least) are worthwhile discussing further: extent of - coverage for 6LO and IPv6 Header Compression, and the continued need - to define a "minimal standard-formed packet". + It updates the definition of standard-formed packets in RFC 2330 to + include IPv6 packets and augments distinguishing aspects of packets, + referred to as Type-P for test packets in RFC 2330. This memo + identifies that IPv4-IPv6 co-existence can challenge measurements + within the scope of the IPPM Framework. Exemplary use cases include, + but are not limited to IPv4-IPv6 translation, NAT, protocol + encapsulation, or IPv6 header compression. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]. Status of This Memo This Internet-Draft is submitted in full conformance with the @@ -40,52 +39,51 @@ Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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." - - This Internet-Draft will expire on January 5, 2017. + This Internet-Draft will expire on September 7, 2017. Copyright Notice - Copyright (c) 2016 IETF Trust and the persons identified as the + 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 . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Packets of Type-P . . . . . . . . . . . . . . . . . . . . . . 3 4. Standard-Formed Packets . . . . . . . . . . . . . . . . . . . 5 - 5. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . 7 - 6. Security Considerations . . . . . . . . . . . . . . . . . . . 7 - 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 - 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8 - 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 - 9.1. Normative References . . . . . . . . . . . . . . . . . . 8 - 9.2. Informative References . . . . . . . . . . . . . . . . . 10 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 + 5. NAT, IPv4-IPv6 Transition and Compression Techniques . . . . 7 + 6. Security Considerations . . . . . . . . . . . . . . . . . . . 9 + 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 + 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9 + 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 + 9.1. Normative References . . . . . . . . . . . . . . . . . . 9 + 9.2. Informative References . . . . . . . . . . . . . . . . . 12 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12 1. Introduction The IETF IP Performance Metrics (IPPM) working group first created a framework for metric development in [RFC2330]. This framework has stood the test of time and enabled development of many fundamental metrics. It has been updated in the area of metric composition [RFC5835], and in several areas related to active stream measurement of modern networks with reactive properties [RFC7312]. @@ -153,49 +151,60 @@ of the exact type of traffic being measured. If the information constituting Type-P at the Source is found to have changed at the Destination (or at a measurement point between the Source and Destination, as in [RFC5644]), then the modified values SHOULD be noted and reported with the results. Some modifications occur according to the conditions encountered in transit (such as congestion notification) or due to the requirements of segments of the Source to Destination path. For example, the packet length will change if IP headers are converted to the alternate version/address - family, or if optional Extension Headers are added or removed. Local - policies in intermediate nodes based on examination of IPv6 Extension - Headers may affect measurement repeatability. If intermediate nodes - follow the recommendations of [RFC7045], repeatability may be - improved to some degree. + family, or if optional Extension Headers are added or removed. Even + header fields like TTL/Hop Limit that typically change in transit may + be relevant to specific tests. For example Neighbor Discovery + Protocol (NDP) [RFC4861] packets are transmitted with Hop Limit value + set to 255, and the validity test specifies that the Hop Limit must + have a value of 255 at the receiver, too. So, while other tests may + intentionally exclude the TTL/Hop Limit value from their Type-P + definition, for this particular test the correct Hop Limit value is + of high relevance and must be part of the Type-P definition. - A Network Address Translator (NAT) on the path can have unpredictable - impact on latency measurement (in terms of the amount of additional - time added), and possibly other types of measurements. It is not - usually possible to control this impact (as testers may not have any - control of the underlying network or middleboxes). There is a - possibility that stateful NAT will lead to unstable performance for a - flow with specific Type-P, since state needs to be created for the - first packet of a flow, and state may be lost later if the NAT runs - out of resources. However, this scenario does not invalidate the - Type-P for testing. The presence of NAT may mean that the measured - performance of Type-P will change between the source and the - destination. This can cause an issue when attempting to correlate - measurements conducted on segments of the path that include or - exclude the NAT. Thus, it is a factor to be aware of when conducting - measurements. + Local policies in intermediate nodes based on examination of IPv6 + Extension Headers may affect measurement repeatability. If + intermediate nodes follow the recommendations of [RFC7045], + repeatability may be improved to some degree. A closely related note: it would be very useful to know if a given Internet component (like host, link, or path) treats equally a class C of different types of packets. If so, then any one of those types of packets can be used for subsequent measurement of the component. This suggests we devise a metric or suite of metrics that attempt to determine C. + Load balancing over parallel paths is one particular example where + such a class C would be more complex to determine in IPPM + measurements. Load balancers often use flow identifiers, computed as + hashes of (specific parts of) the packet header, for deciding among + the available parallel paths a packet will traverse. Packets with + identical hashes are assigned to the same flow and forwarded to the + same resource in the load balancer's pool. The presence of a load + balancer on the measurement path, as well as the specific headers and + fields that are used for the forwarding decision, are not known when + measuring the path as a black-box. Potential assessment scenarios + include the measurement of one of the parallel paths, and the + measurement of all available parallel paths that the load balancer + can use. Knowledge of a load balancer's flow definition + (alternatively: its class C specific treatment in terms of header + fields in scope of hash operations) is therefore a prerequisite for + repeatable measurements. A path may have more than one stage of load + balancing, adding to class C definition complexity. + 4. Standard-Formed Packets Unless otherwise stated, all metric definitions that concern IP packets include an implicit assumption that the packet is *standard- formed*. A packet is standard-formed if it meets all of the following criteria: + It includes a valid IP header: see below for version-specific criteria. @@ -223,22 +232,25 @@ hop, or it possesses the maximum TTL of 255. o It does not contain IP options unless explicitly noted. For an IPv6 ([RFC2460] and updates) packet to be standard-formed, the following criteria are required: o The version field is 6. o Its total length corresponds to the size of the IPv6 header (40 - octets) plus the length of the payload (including Extension - Headers) as given in the IPv6 header. + octets) plus the length of the payload as given in the IPv6 + header. + + o The payload length value for this packet (including Extension + Headers) conforms to the IPv6 specifications. o Either the packet possesses sufficient Hop Count to travel from the Source to the Destination if the Hop Count is decremented by one at each hop, or it possesses the maximum Hop Count of 255. o Either the packet does not contain IP Extension Headers, or it contains the correct number and type of headers as specified in the packet, and the headers appear in the standard-conforming order (Next Header). @@ -301,25 +313,92 @@ + It contains no options or Extension Headers. (Note that we do not define its protocol field, as different values may lead to different treatment by the network.) When defining IP metrics we keep in mind that no packet smaller or simpler than this can be transmitted over a correctly operating IP network. -5. Conclusions +5. NAT, IPv4-IPv6 Transition and Compression Techniques This memo adds the key considerations for utilizing IPv6 in two - critical conventions of the IPPM Framework. It is RECOMMENDED to - adopt these new considerations in measurements involving IPv6. + critical conventions of the IPPM Framework, namely packets of Type-P + and standard-formed packets. The need for co-existence of IPv4 and + IPv6 has originated transitioning standards like the Framework for + IPv4/IPv6 Translation in [RFC6144] or IP/ICMP Translation Algorithms + in [RFC6145] and [RFC7757]. + + The definition and execution of measurements within the context of + the IPPM Framework is challenged whenever such translation mechanisms + are present along the measurement path. In particular use cases like + IPv4-IPv6 translation, NAT, protocol encapsulation, or IPv6 header + compression may result in modification of the measurement packet's + Type-P along the path. All these changes must be reported. + Exemplary consequences include, but are not limited to: + + o Modification or addition of headers or header field values in + intermediate nodes. As noted in Section 4 for IPv6 extension + header manipulation, NAT, IPv4-IPv6 transitioning or IPv6 header + compression mechanisms may result in changes of the measurement + packets' Type-P, too. Consequently, hosts along the measurement + path may treat packets differently because of the Type-P + modification. Measurements at observation points along the path + may also need extra context to uniquely identify a packet. + + o Network Address Translators (NAT) on the path can have + unpredictable impact on latency measurement (in terms of the + amount of additional time added), and possibly other types of + measurements. It is not usually possible to control this impact + (as testers may not have any control of the underlying network or + middleboxes). There is a possibility that stateful NAT will lead + to unstable performance for a flow with specific Type-P, since + state needs to be created for the first packet of a flow, and + state may be lost later if the NAT runs out of resources. + However, this scenario does not invalidate the Type-P for testing + - for example the purpose of a test might be exactly to quantify + the NAT's impact on delay variation. The presence of NAT may mean + that the measured performance of Type-P will change between the + source and the destination. This can cause an issue when + attempting to correlate measurements conducted on segments of the + path that include or exclude the NAT. Thus, it is a factor to be + aware of when conducting measurements. + + o Variable delay due to internal state. One side effect of changes + due to IPv4-IPv6 transitioning mechanisms is the variable delay + that intermediate nodes spend for header modifications. Similar + to NAT the allocation of internal state and establishment of + context within intermediate nodes may cause variable delays, + depending on the measurement stream pattern and position of a + packet within the stream. For example the first packet in a + stream will typically trigger allocation of internal state in an + intermediate IPv4-IPv6 transition host. Subsequent packets can + benefit from lower processing delay due to the existing internal + state. However, large inter-packet delays in the measurement + stream may result in the intermediate host deleting the associated + state and needing to re-establish it on arrival of another stream + packet. It is worth noting that this variable delay due to + internal state allocation in intermediate nodes can be an explicit + use case for measurements. + + o Variable delay due to packet length. IPv4-IPv6 transitioning or + header compression mechanisms modify the length of measurement + packets. The modification of the packet size may or may not + change the way how the measurement path treats the packets. + + Points that are worthwhile discussing further: handling of large + packets in IPv6 (including fragment extension headers, PMTUD, + PLMTUD), extent of coverage for 6LO and IPv6 Header Compression, and + the continued need to define a "minimal standard-formed packet". + + . 6. Security Considerations The security considerations that apply to any active measurement of live paths are relevant here as well. See [RFC4656] and [RFC5357]. When considering privacy of those involved in measurement or those whose traffic is measured, the sensitive information available to potential observers is greatly reduced when using active techniques which are within this scope of work. Passive observations of user @@ -380,34 +459,47 @@ [RFC4494] Song, JH., Poovendran, R., and J. Lee, "The AES-CMAC-96 Algorithm and Its Use with IPsec", RFC 4494, DOI 10.17487/RFC4494, June 2006, . [RFC4656] Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M. Zekauskas, "A One-way Active Measurement Protocol (OWAMP)", RFC 4656, DOI 10.17487/RFC4656, September 2006, . + [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, + "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, + DOI 10.17487/RFC4861, September 2007, + . + [RFC5357] Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J. Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)", RFC 5357, DOI 10.17487/RFC5357, October 2008, . [RFC5644] Stephan, E., Liang, L., and A. Morton, "IP Performance Metrics (IPPM): Spatial and Multicast", RFC 5644, DOI 10.17487/RFC5644, October 2009, . [RFC5835] Morton, A., Ed. and S. Van den Berghe, Ed., "Framework for Metric Composition", RFC 5835, DOI 10.17487/RFC5835, April 2010, . + [RFC6144] Baker, F., Li, X., Bao, C., and K. Yin, "Framework for + IPv4/IPv6 Translation", RFC 6144, DOI 10.17487/RFC6144, + April 2011, . + + [RFC6145] Li, X., Bao, C., and F. Baker, "IP/ICMP Translation + Algorithm", RFC 6145, DOI 10.17487/RFC6145, April 2011, + . + [RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6 Datagrams over IEEE 802.15.4-Based Networks", RFC 6282, DOI 10.17487/RFC6282, September 2011, . [RFC6437] Amante, S., Carpenter, B., Jiang, S., and J. Rajahalme, "IPv6 Flow Label Specification", RFC 6437, DOI 10.17487/RFC6437, November 2011, . @@ -419,20 +511,25 @@ [RFC7045] Carpenter, B. and S. Jiang, "Transmission and Processing of IPv6 Extension Headers", RFC 7045, DOI 10.17487/RFC7045, December 2013, . [RFC7312] Fabini, J. and A. Morton, "Advanced Stream and Sampling Framework for IP Performance Metrics (IPPM)", RFC 7312, DOI 10.17487/RFC7312, August 2014, . + [RFC7757] Anderson, T. and A. Leiva Popper, "Explicit Address + Mappings for Stateless IP/ICMP Translation", RFC 7757, + DOI 10.17487/RFC7757, February 2016, + . + 9.2. Informative References [RFC7594] Eardley, P., Morton, A., Bagnulo, M., Burbridge, T., Aitken, P., and A. Akhter, "A Framework for Large-Scale Measurement of Broadband Performance (LMAP)", RFC 7594, DOI 10.17487/RFC7594, September 2015, . Authors' Addresses