RFC 7571

GMPLS RSVP-TE Extensions for Lock Instruct and Loopback

📅 published July 2015, from ietf

GMPLS RSVP-TE Extensions for Lock Instruct and Loopback 🎀

okay bestie, this RFC is a Standards Track document from the IETF, which means it's an official Internet spec 💅 It was published in July 2015 as RFC 7571, and its ISSN is 2070-1721. The authors are J. Dong, M. Chen (both from Huawei Technologies), Z. Li (China Mobile), and D. Ceccarelli (Ericsson). The header doesn't list anything it obsoletes or updates, so it's a brand new standard, not a replacement or patch for an older one 🌸

Abstract

okay so the whole point is this: this doc adds extensions to Resource Reservation Protocol - Traffic Engineering (RSVP-TE) so it can handle Lock Instruct (LI) and Loopback (LB) for Label Switched Paths (LSPs) 🦋 These mechanisms are meant for technologies that use Generalized MPLS (GMPLS) for the control plane, and that's the whole vibe ✨

Status of This Memo

this is an Internet Standards Track document 🫶 It's a product of the Internet Engineering Task Force (IETF), so it represents the consensus of the IETF community. It got public review and was approved for publication by the Internet Engineering Steering Group (IESG). If you want more info on how Internet Standards work, check out Section 2 of RFC 5741.

If you want the current status, any errata, or a way to send feedback, head to http://www.rfc-editor.org/info/rfc7571 💜

Copyright Notice

the copyright is held by the IETF Trust and the document authors, and the year is 2015. All rights are reserved 🌈 This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents, which you can find at http://trustee.ietf.org/license-info as they stood on the publication date. Please actually read those, bestie, because they explain your rights and restrictions. Any Code Components pulled out of this document must include the Simplified BSD License text described in Section 4.e of the Trust Legal Provisions, and they come without warranty as described in that license 🙈

1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
  1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
2.  Flag Definitions for LI and LB  . . . . . . . . . . . . . . .   3
  2.1.  Lock Instruct Indication  . . . . . . . . . . . . . . . .   3
  2.2.  Extensions for Loopback . . . . . . . . . . . . . . . . .   3
3.  Operational Procedures  . . . . . . . . . . . . . . . . . . .   3
  3.1.  Lock Instruct . . . . . . . . . . . . . . . . . . . . . .   3
  3.2.  Loopback  . . . . . . . . . . . . . . . . . . . . . . . .   4
4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
  4.1.  Attribute Flags . . . . . . . . . . . . . . . . . . . . .   6
  4.2.  RSVP Error Value Sub-Codes  . . . . . . . . . . . . . . .   6
  4.3.  Allocation Rule for ERO Subobjects  . . . . . . . . . . .   6
5.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
  6.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
  6.2.  Informative References  . . . . . . . . . . . . . . . . .   8
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .   9
Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1. Introduction ✨

okay so the requirements for Lock Instruct (LI) and Loopback (LB) in the MPLS-TP transport profile live in [RFC5860], and the framework for LI and LB lives in [RFC6371] 💖 An LSP that's been locked with LI is not allowed to carry user data traffic. And LB can only be applied to an LSP that was locked first. Order matters, bestie 🔥

LI and LB are super useful Operations, Administration, and Maintenance (OAM) functions for any technology that uses GMPLS for the control plane. That includes time-division multiplexing, wavelength-division multiplexing, and packet switching 🧚 It makes total sense to reuse and extend the GMPLS control-plane protocol so you get one unified way to provision LI and LB across all of those technologies. Main character energy 👑

Now, [RFC7487] already handles RSVP-TE extensions for configuring proactive MPLS-TP OAM functions like Continuity Check (CC), Connectivity Verification (CV), Delay Measurement (DM), and Loss Measurement (LM) 🦋 But on-demand OAM stuff like LI and LB? Not covered there. That's the gap this doc fills 🫶

So this document specifies extensions to Resource Reservation Protocol-Traffic Engineering (RSVP-TE) to support lock instruct and loopback mechanisms for LSPs. These mechanisms apply to technologies that use GMPLS for the control plane. For a network that supports MPLS-TP, the mechanisms here are complementary to [RFC6435] 💅

1.1. Requirements Language

the BCP 14 key words in this document are the ones you're used to seeing: "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL". They're to be interpreted as described in RFC 2119 [RFC2119] 🌸

2. Flag Definitions for LI and LB 🎀

2.1. Lock Instruct Indication

so to show whether an LSP is locked or unlocked, you use the A (Administratively down) bit in the Administrative Status (ADMIN_STATUS) Object, which is defined in [RFC3471] and [RFC3473] 🍓

2.2. Extensions for Loopback

to show that an LSP is in loopback mode, a brand new bit flag gets defined in the Attribute Flags TLV from [RFC5420] 🧚

Loopback flag:

This flag says a particular node on the LSP is required to enter loopback mode. It can also be used to specify the loopback state of that node 🦋 Here are the details, bestie:

Bit number: 13
Attribute flag carried in Path message: Yes
Attribute flag carried in Resv message: No
Attribute flag carried in the Record Route Object (RRO) Attributes subobject: Yes

3. Operational Procedures 💜

3.1. Lock Instruct

okay this is where it gets spicy 🔥 Lock mode and unlock mode both follow the same pattern: the ingress sends a request, the egress tries to do it, and the egress either confirms with a Resv or reports a failure with a PathErr. Let's go step by step.

When an ingress node wants to put an LSP into lock mode, it MUST send a Path message with the Administratively down (A) bit used as specified above, and the Reflect (R) bit in the ADMIN_STATUS Object set 🌈

Once the egress node gets that Path message, it SHOULD try to take the LSP out of service ✨ If the egress locks the LSP successfully, it MUST send a Resv message with the A bit in the ADMIN_STATUS Object set. If it doesn't manage to lock it, it MUST send a PathErr message with the Error Code "OAM Problem" [RFC7260] and the new Error Value "Lock Failure". And after that failure, the following Resv messages MUST be sent with the A bit cleared 🙈

Once an LSP is in lock mode, the subsequent Path and Resv messages MUST keep the A bit in the ADMIN_STATUS Object set. No sneaking it off, bestie 💅

When the ingress node wants to take the LSP out of lock mode, it MUST send a Path message with the A bit in the ADMIN_STATUS Object cleared 🦋

On receipt of this Path message, the egress node SHOULD try to bring the LSP back to service 🫶 If the egress unlocks the LSP successfully, it MUST send a Resv message with the A bit in the ADMIN_STATUS Object cleared. Otherwise, it MUST send a PathErr message with the Error Code "OAM Problem" [RFC7260] and the new Error Value "Unlock Failure", and the following Resv messages MUST be sent with the A bit set 😭

And finally, when an LSP is taken out of lock mode, the subsequent Path and Resv messages MUST keep the A bit in the ADMIN_STATUS Object cleared. Iconic closure, periodt ✨

4. IANA Considerations ✨

okay so IANA is the one handing out the new numbers and codes here, and this section is the little receipt list of everything that got assigned by this document. let's go 💅

4.1. Attribute Flags

IANA keeps a registry called "Resource Reservation Protocol-Traffic Engineering (RSVP-TE) Parameters", and inside it is a sub-registry called "Attribute Flags" 🎀

IANA has given a new bit flag its own spot, and it's giving main character energy 🦋

 Bit |           | Attribute  | Attribute  |     |     |
 No. | Name      | Flags Path | Flags Resv | RRO | ERO |  Reference
-----+-----------+------------+------------+-----+-----+-------------
  13 | Loopback  |   Yes      |   No       | Yes | Yes |this document

4.2. RSVP Error Value Sub-Codes

Next up, the error codes. IANA keeps a registry called "Resource Reservation Protocol (RSVP) Parameters", with a sub-registry called "Error Codes and Globally-Defined Error Value Sub-Codes" 🌸

IANA has assigned four new Error Value sub-codes for the "OAM Problem" Error Code. Lowkey iconic, all four of them 🔥

   Value   |  Description                | Reference
-----------+-----------------------------+--------------
    26    |  Lock Failure               | this document
    27    |  Unlock Failure             | this document
    28    |  Loopback Failure           | this document
    29    |  Exit Loopback Failure      | this document

4.3. Allocation Rule for ERO Subobjects

For the ERO subobject types, IANA keeps a registry called "Resource Reservation Protocol (RSVP) Parameters" with a sub-registry called "Class Names, Class Numbers, and Class Types" 🧚

For the Explicit Route Object, the allocation rule for subobject types in the range 5-31 (0x05 - 0x1F) has been updated to this:

5-31     Unassigned    (For explicit resource identification)

5. Security Considerations 🔐

okay this part is serious bestie, so we're gonna keep the full energy here 😭

This document doesn't bring any brand new security issues to the table. Everything worth worrying about is already covered in [RFC3209], [RFC3473], and [RFC7570]. If you want the deep dive on GMPLS security and how to mitigate attacks, go read "Security Framework for MPLS and GMPLS Networks" [RFC5920]. It is the full tea ☕

Heads up: reporting the loopback status using the RRO might reveal details about the node that the operator wants to keep confidential. Not cute. The privacy considerations in paragraph 3 of Section 5 of [RFC7570] also apply to this document, so please don't skip them 🙈

6. References 📚

6.1. Normative References

These are the must-reads for understanding this one 🫶

[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>.

[RFC3209]  Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
           and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
           Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
           <http://www.rfc-editor.org/info/rfc3209>.

[RFC3471]  Berger, L., Ed., "Generalized Multi-Protocol Label
           Switching (GMPLS) Signaling Functional Description", RFC
           3471, DOI 10.17487/RFC3471, January 2003,
           <http://www.rfc-editor.org/info/rfc3471>.

[RFC3473]  Berger, L., Ed., "Generalized Multi-Protocol Label
           Switching (GMPLS) Signaling Resource ReserVation Protocol-
           Traffic Engineering (RSVP-TE) Extensions", RFC 3473,
           DOI 10.17487/RFC3473, January 2003,
           <http://www.rfc-editor.org/info/rfc3473>.

[RFC5420]  Farrel, A., Ed., Papadimitriou, D., Vasseur, JP., and A.
           Ayyangarps, "Encoding of Attributes for MPLS LSP
           Establishment Using Resource Reservation Protocol Traffic
           Engineering (RSVP-TE)", RFC 5420, DOI 10.17487/RFC5420,
           February 2009, <http://www.rfc-editor.org/info/rfc5420>.

[RFC5860]  Vigoureux, M., Ed., Ward, D., Ed., and M. Betts, Ed.,
           "Requirements for Operations, Administration, and
           Maintenance (OAM) in MPLS Transport Networks", RFC 5860,
           DOI 10.17487/RFC5860, May 2010,
           <http://www.rfc-editor.org/info/rfc5860>.

[RFC7260]  Takacs, A., Fedyk, D., and J. He, "GMPLS RSVP-TE
           Extensions for Operations, Administration, and Maintenance
           (OAM) Configuration", RFC 7260, DOI 10.17487/RFC7260, June
           2014, <http://www.rfc-editor.org/info/rfc7260>.

[RFC7570]  Margaria, C., Ed., Martinelli, G., Balls, S., and B.
           Wright, "Label Switched Path (LSP) Attribute in the
           Explicit Route Object (ERO)", RFC 7570,
           DOI 10.17487/RFC7570, July 2015,
           <http://www.rfc-editor.org/info/rfc7570>.

6.2. Informative References

These ones are good for extra context, not required reading 🌈

[RFC5920]  Fang, L., Ed., "Security Framework for MPLS and GMPLS
           Networks", RFC 5920, DOI 10.17487/RFC5920, July 2010,
           <http://www.rfc-editor.org/info/rfc5920>.

[RFC6371]  Busi, I., Ed. and D. Allan, Ed., "Operations,
           Administration, and Maintenance Framework for MPLS-Based
           Transport Networks", RFC 6371, DOI 10.17487/RFC6371,
           September 2011, <http://www.rfc-editor.org/info/rfc6371>.

[RFC6435]  Boutros, S., Ed., Sivabalan, S., Ed., Aggarwal, R., Ed.,
           Vigoureux, M., Ed., and X. Dai, Ed., "MPLS Transport
           Profile Lock Instruct and Loopback Functions", RFC 6435,
           DOI 10.17487/RFC6435, November 2011,
           <http://www.rfc-editor.org/info/rfc6435>.

[RFC7487]  Bellagamba, E., Takacs, A., Mirsky, G., Andersson, L.,
           Skoldstrom, P., and D. Ward, "Configuration of Proactive
           Operations, Administration, and Maintenance (OAM)
           Functions for MPLS-Based Transport Networks Using RSVP-
           TE", RFC 7487, DOI 10.17487/RFC7487, March 2015,
           <http://www.rfc-editor.org/info/rfc7487>.

Acknowledgments 🫶

The authors want to thank Greg Mirsky, Lou Berger, and Francesco Fondelli for their comments and suggestions. Iconic behaviour from the whole squad 👑

Authors' Addresses 💌

Jie Dong
Huawei Technologies
Huawei Campus, No.156 Beiqing Rd.
Beijing  100095
China

Email: jie.dong@huawei.com


Mach(Guoyi) Chen
Huawei Technologies
Huawei Campus, No.156 Beiqing Rd.
Beijing  100095
China

Email: mach.chen@huawei.com


Zhenqiang Li
China Mobile
Unit2, Dacheng Plaza, No. 28 Xuanwumenxi Ave.
Beijing  100053
China

Email: lizhenqiang@chinamobile.com


Daniele Ceccarelli
Ericsson
Via A. Negrone 1/A
Genova - Sestri Ponente
Italy

Email: daniele.ceccarelli@ericsson.com

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