RFC 5618

Mixed Security Mode for the Two-Way Active Measurement Protocol (TWAMP)

📅 published August 2009, from ietf

RFC 5618: Mixed Security Mode for the Two-Way Active Measurement Protocol (TWAMP) 🦋

okay bestie, so this one is from the Network Working Group and it's a Standards Track doc, dated August 2009 💅. The authors are A. Morton (AT&T Labs) and K. Hedayat (EXFO). It Updates RFC 5357, which is TWAMP itself, and it doesn't obsolete anything 🫶. This is RFC number 5618, and it's a whole extension for TWAMP, so you'll want to know TWAMP first. Let's go 🌸

Abstract ✨

this memo is a simple extension to TWAMP (the Two-Way Active Measurement Protocol) 🎀 it lets you use different security modes in TWAMP-Control and TWAMP-Test at the same time, which is honestly so iconic 😭 it also sets up a brand new IANA registry for extra features, called the TWAMP Modes registry 🧚

Status of This Memo

this document is an Internet standards track protocol for the Internet community, and it's asking everyone for discussion and suggestions for improvements 🌈 if you want to know where this protocol stands in standardization, check the current edition of the "Internet Official Protocol Standards" (STD 1) 📚 and yes, you're allowed to distribute this memo as much as you want, distribution is unlimited ✨

Copyright Notice

© 2009 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, as they were on the publication date. the link is http://trustee.ietf.org/license-info 🔗 please read those carefully, bestie, because they explain your rights and restrictions 🫶

some of this document may include material from IETF Documents or IETF Contributions that were published or made public before November 10, 2008 🍓 the people who control the copyright on some of that material might not have given the IETF Trust permission to allow modifications outside the IETF Standards Process 🙈 so unless you get a proper license from those copyright holders, you can't modify this document outside the IETF Standards Process, and you can't make derivative works of it outside that process either 💀 the only exceptions are formatting it for publication as an RFC, or translating it into languages other than English 🌸

1. Introduction ....................................................2
   1.1. Requirements Language ......................................3
2. Purpose and Scope ...............................................3
3. TWAMP Control Extensions ........................................3
   3.1. Extended Control Connection Setup ..........................3
4. Extended TWAMP Test .............................................5
   4.1. Sender Behavior ............................................5
        4.1.1. Packet Timings ......................................5
        4.1.2. Packet Format and Content ...........................5
   4.2. Reflector Behavior .........................................6
5. Security Considerations .........................................6
6. IANA Considerations .............................................6
   6.1. Registry Specification .....................................6
   6.2. Registry Management ........................................6
   6.3. Experimental Numbers .......................................7
   6.4. Initial Registry Contents ..................................7
7. Acknowledgements ................................................7
8. Normative References ............................................7

1. Introduction ✨

okay so TWAMP [RFC5357] is basically an extension of OWAMP (the One-Way Active Measurement Protocol) [RFC4656] 💖 the TWAMP spec got lots of review as it got close to done, and that review produced a bunch of recommendations for new features 🔥 there are a growing number of TWAMP implementations now, and everyone expects widespread usage 🦋 there are even devices built to test implementations for protocol compliance, which is literally so extra and I love it 💅

this memo is a simple extension for TWAMP: the option to use different security modes in the TWAMP-Control and TWAMP-Test protocols, which we're calling mixed security mode 🎀 it also describes that new IANA registry, the TWAMP Modes registry 🧚

here's the vibe: when the Server and Control-Client have agreed to use mixed security mode during control connection setup, then the Control-Client, the Server, the Session-Sender, and the Session-Reflector MUST all conform to the requirements of this mode, as described in Sections 3, 4, and 5 👑 no skipping, bestie 😭

this memo updates [RFC5357] 🌈

1.1. 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] 🤓 these are the official capital-letter keywords, so when you see them in caps, they're doing real work 💜

2. Purpose and Scope 🌸

the whole point of this memo is to describe and specify an extension for TWAMP [RFC5357], and to request that a registry gets set up for future TWAMP extensions 🧚

the scope is limited to the following:

Extending the modes of operation by assigning one new value in the Modes field (see Section 3.1 of [RFC4656]), while keeping backward compatibility with TWAMP [RFC5357] implementations 🦋 this value adds the OPTIONAL ability to use different security modes in the TWAMP-Control and TWAMP-Test protocols 🎀 the motivation is to let the low-packet-rate TWAMP-Control protocol use a stronger mode of integrity protection than the one used in the TWAMP-Test protocol 💪 that makes total sense because Control sends way fewer packets 🫶

3. TWAMP Control Extensions 💖

the TWAMP-Control protocol is a derivative of the OWAMP-Control protocol, and it coordinates a two-way measurement capability ✨ all TWAMP-Control messages are similar in format and follow similar guidelines to those defined in Section 3 of [RFC4656], with the exceptions described in TWAMP [RFC5357] and in the following sections 🌈

all OWAMP-Control messages apply to TWAMP-Control, except for the Fetch-Session command 🙈

3.1. Extended Control Connection Setup 🔥

TWAMP-Control connection establishment follows the same procedure defined in Section 3.1 of [RFC4656] 📚 this extended mode assigns one new bit position (and value) so the Test protocol security mode can operate in Unauthenticated mode, while the Control protocol operates in Encrypted mode 🦋 with this extension, the complete set of TWAMP Mode values looks like this:

Value  Description             Reference/Explanation

0      Reserved

1      Unauthenticated         RFC 4656, Section 3.1

2      Authenticated           RFC 4656, Section 3.1

4      Encrypted               RFC 4656, Section 3.1

8      Unauth. TEST protocol,  new bit position (3)
       Encrypted CONTROL

in the original OWAMP and TWAMP Modes field, setting bit position 0, 1, or 2 indicated the security mode of the Control protocol, and the Test protocol inherited that same mode (see Section 4 of [RFC4656]) 🧠

in this extension to TWAMP, when the Control-Client sets Modes Field bit position 3, it SHALL discontinue the inheritance of the security mode in the Test protocol, and each protocol's mode SHALL be as specified below 💅 when the desired TWAMP-Test protocol mode is identical to the Control Session mode, the corresponding Modes Field bit (position 0, 1, or 2) SHALL be set by the Control-Client 🫶 the table below shows the combinations of integrity protection that are permissible in TWAMP (with this extension) 🌸 the TWAMP-Control and TWAMP-Test protocols SHALL use the mode in each column that corresponds to the bit position set in the Modes Field 👑

--------------------------------------------------------
Protocol | Permissible Mode Combinations (Modes bit set)
--------------------------------------------------------
Control  |    Unauth.(0)|  Auth. == Encrypted (1,2,3)
--------------------------------------------------------
         |    Unauth.(0)|         Unauth.  (3)
         -----------------------------------------------
Test     |              |          Auth.(1)
         -----------------------------------------------
         |              |        Encrypted (2)
--------------------------------------------------------

note that the TWAMP-Control protocol security measures are identical in the Authenticated and Encrypted Modes 🙌 so only one new bit position (3) is needed to convey the single mixed security mode 🎀

the value of the Modes Field that the Server sends in the Server-Greeting message is the bit-wise OR of the modes (bit positions) it's willing to support during this session 🧚 so the last four bits of the 32-bit Modes Field are used 🦋 when no other features are activated, the first 28 bits MUST be zero 🚨 a client conforming to this extension of [RFC5357] MAY ignore the values in the first 28 bits of the Modes Field, or it MAY support other features communicated in those bit positions 🌈

other ways in which TWAMP extends OWAMP are described in [RFC5357] 💜

5. Security Considerations 🔐

okay so bestie, this is the part where we talk about keeping things safe 🫶 The extended mixed mode lets you lock down TWAMP-Control with stronger security and integrity protection, while TWAMP-Test can focus on accuracy or efficiency. So you get more overall security than the older options gave you. Those older options sometimes forced TWAMP-Control to be less secure because resources were tight, and that's only okay when unauthenticated TWAMP-Test isn't a big worry 💅

Any active measurement of live networks comes with its own security concerns, and those apply here too. Go check [RFC4656] and [RFC5357] for the details 📚✨

6. IANA Considerations 🦋

this memo adds one security mode bit position/value on top of what the OWAMP-Control spec [RFC4656] already has, and it explains how things behave when the new mode is in use 🌸 IANA made a registry for the TWAMP Modes field, and this field is an official way to extend TWAMP. So it's basically built to grow 🌱

6.1. Registry Specification 🎀

IANA made a TWAMP Modes registry. TWAMP Modes show up in TWAMP Server Greeting messages and Set-up Response messages, following Section 3.1 of [RFC4656] and Section 3.1 of [RFC5357], and this memo extends them. Right now modes are set as single bits in the 32-bit Modes Field 🧚 Later on there might be more complex encodings, so the registry can hold a total of 2^32 possible assignments. Wild, right? 😭

6.2. Registry Management 👑

since the TWAMP Modes registry can hold a max of 2^32 values, and TWAMP is an IETF protocol, this registry can only be updated by "IETF Review" as defined in [RFC5226]. That's an RFC covering how registries get used, and it has to be approved by the IESG 🔥 For the TWAMP Modes registry, the authors expect new features to get monotonically increasing single bit positions in the range [0-31], unless there's a really good reason to do something else. More complex encoding than single bit positions might be used down the line to reach that 2^32 value space 🌈

6.3. Experimental Numbers 🧪

no experimental values are assigned in the Modes Registry right now 🙈

6.4. Initial Registry Contents 💜

here's what the TWAMP Modes Registry starts with 👇

TWAMP Modes Registry
Value  Description             Semantics Definition
0      Reserved                RFC 5618

1      Unauthenticated         RFC 4656, Section 3.1

2      Authenticated           RFC 4656, Section 3.1

4      Encrypted               RFC 4656, Section 3.1

8      Unauth. TEST protocol,  RFC 5618, Section 3.1
       Encrypted CONTROL

7. Acknowledgements 🫶

the authors want to thank Len Ciavattone and Joel Jaeggli for their super helpful review and comments 💖

8. Normative References 📚

these are the references that are required reading, bestie 🍓

[RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
           Requirement Levels", BCP 14, RFC 2119, March 1997.

[RFC4656]  Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M.
           Zekauskas, "A One-way Active Measurement Protocol
           (OWAMP)", RFC 4656, September 2006.

[RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
           IANA Considerations Section in RFCs", BCP 26, RFC 5226,
           May 2008.

[RFC5357]  Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J.
           Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)",
           RFC 5357, October 2008.

Authors' Addresses 💅

meet the authors ✨

Al Morton
AT&T Labs
200 Laurel Avenue South
Middletown, NJ  07748
USA

Phone: +1 732 420 1571
Fax:   +1 732 368 1192
EMail: acmorton@att.com
URI:   http://home.comcast.net/~acmacm/


Kaynam Hedayat
EXFO
285 Mill Road
Chelmsford, MA  01824
USA

Phone: +1 978 367 5611
Fax:   +1 978 367 5700
EMail: kaynam.hedayat@exfo.com
URI:   http://www.exfo.com/

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