RFC 8330

OSPF Traffic Engineering (OSPF-TE) Link Availability Extension for Links with Variable Discrete Bandwidth

📅 published February 2018, from ietf

RFC 8330: OSPF Traffic Engineering (OSPF-TE) Link Availability Extension for Links with Variable Discrete Bandwidth 💖

RFC number: 8330 🎀
Stream: Internet Engineering Task Force (IETF) 🌐
Written by: H. Long, M. Ye (both Huawei Technologies Co., Ltd.), G. Mirsky (ZTE), A. D'Alessandro (Telecom Italia S.p.A.), and H. Shah (Ciena) 👑
Category: Standards Track ✨
ISSN: 2070-1721
Date: February 2018 📅
Obsoletes / Updates: the title block doesn't list any RFCs that it obsoletes or updates 🫶

Abstract 🌈

Okay so, some networks have links whose bandwidth can change in steps, like microwave and copper. The bandwidth can jump between discrete values depending on what's happening in the environment around the link. During network planning, people usually describe these links using the word "availability" ✨. This document defines a new type of Generalized Switching Capability-Specific Information (SCSI) TLV to extend the Generalized Multiprotocol Label Switching (GMPLS) Open Shortest Path First (OSPF) routing protocol 🦋. That extension can be used for route computation in a network that has links like this.

Now, here's the important bit 👀: this document only covers how the availability information gets distributed. How a link's availability is actually measured, and how that info gets used for route computation, is totally outside the scope of this doc. Technology-specific documents are supposed to reference this one to describe their own uses 💅.

Status of This Memo 📣

This is an Internet Standards Track document ✨.

This document is a product of the Internet Engineering Task Force (IETF) 🌐. It represents the consensus of the IETF community. It went through public review and got approved for publication by the Internet Engineering Steering Group (IESG). If you want more info on Internet Standards, check out Section 2 of RFC 7841 📚.

For info on the current status of this document, any errata, and how to give feedback, go to https://www.rfc-editor.org/info/rfc8330 🔗.

Copyright Notice 🔒

This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) as they are in effect on the date of publication. Please read these documents carefully, because 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 they're provided without warranty as described in the Simplified BSD License 💜.

Table of Contents 🗂️

   1. Introduction ....................................................3
      1.1. Conventions Used in This Document ..........................3
   2. Abbreviations ...................................................4
   3. Overview ........................................................4
   4. TE Metric Extension to OSPF-TE ..................................5
      4.1. Availability SCSI-TLV ......................................5
      4.2. Processing Procedures ......................................6
   5. Security Considerations .........................................6
   6. IANA Considerations .............................................7
   7. References ......................................................7
      7.1. Normative References .......................................7
      7.2. Informative References .....................................8
   Acknowledgments ...................................................10
   Authors' Addresses ................................................10

1. Introduction ✨

Some data-plane technologies, like microwave and copper, can switch their maximum physical bandwidth smoothly through a set of known discrete values 🌸. The parameter "availability" (described in [G.827], [F.1703], and [P.530]) is often used to describe link capacity. Availability is a time-scale thing: it's the proportion of operating time during which the requested bandwidth is actually guaranteed 🕰️.

To set up a Label Switched Path (LSP) across these links, the nodes need availability information so they can check the bandwidth before making a bandwidth reservation 🔍. Giving different availability classes to these links helps with planning link capacity more efficiently for different types of services 📊. The operator decides the link availability info and configures it statically. It's usually based on the availability needs of the services that are expected to run on the LSP. For example, voice service usually needs "five nines" availability, while non-real-time services can get by with four or three nines 📞.

For route computation, you need both the availability info and the bandwidth resource info 🧠. Different service types may need different availability guarantees, so a link might need to be associated with multiple <availability, bandwidth> pairs 💜.

In this document, a new type of Generalized SCSI-TLV called the Availability SCSI-TLV is defined 🎀. Technology-specific documents are meant to reference this document to describe their specific uses. The signaling extension that supports links with variable discrete bandwidth is defined in [RSVP-TE-Availability] 📡.

1.1. Conventions Used in This Document 📜

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here 🔤.

2. Abbreviations 🔤

Here are the abbreviations used in this document 💅:

   GMPLS     Generalized Multiprotocol Label Switching

   ISCD      Interface Switching Capability Descriptor

   LSA       Link State Advertisement

   LSP       Label Switched Path

   OSPF      Open Shortest Path First

   SCSI      Switching Capability-Specific Information

   SPF       Shortest Path First

   TE        Traffic Engineering

   TLV       Type-Length-Value

3. Overview 🌸

A node that has links with variable discrete bandwidth attached should include an <availability, bandwidth> information list in its OSPF-TE LSA messages 🌈. The list maps each link's nominal bandwidth to its availability level, and the node(s) use it for path calculation 🧭. Setting up an LSP requires this info to be flooded through the network so the nodes or the PCE can use it for path computation 🌊. This document defines a new type of Generalized SCSI-TLV called the Availability SCSI-TLV. The computed path can then be provisioned through the signaling protocol [RSVP-TE-Availability] 🦋.

Note: The mechanisms described in this document only distribute availability information. How the information gets measured, or how it gets used for route computation, is outside the scope of this document ⚠️.

4. TE Metric Extension to OSPF-TE 🦋

4.1. Availability SCSI-TLV 🎀

The Generalized SCSI is defined in [RFC8258]. This document defines a new type of Generalized SCSI-TLV called the Availability SCSI-TLV 💖. The Availability SCSI-TLV can be included one or more times 🔁. It has the following format 👇:

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |               Type            |               Length          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                   Availability level                          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                   LSP Bandwidth at Availability level n       |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Type: 0x000A, 16 bits 🏷️

Length: 2 octets (16 bits) 📏

Availability level: 32 bits 🎯

This field is a binary32-format floating-point number, as defined by [IEEE754-2008]. The bytes are sent in network order, which means the byte with the sign bit goes out first 🔢. This field describes the decimal value of the availability guarantee of the Switching Capability in the Interface Switching Capability Descriptor object [RFC4202]. The value MUST be less than 1 🚫. The Availability level field is usually written as 0.99/0.999/0.9999/0.99999 ✨.

LSP Bandwidth at Availability level n: 32 bits 🌊

This field is a 32-bit IEEE floating-point number, as defined by [IEEE754-2008]. The bytes are sent in network order, so the byte with the sign bit comes first 🔢. This field describes the LSP bandwidth for the availability level shown in the Availability level field. The units are bytes per second 💧.

4.2. Processing Procedures 💅

The ISCD lets routing protocols like OSPF carry technology-specific info in the "Switching Capability-specific information" field, see [RFC4203] 📦. A node that advertises an interface with a Switching Capability that supports variable discrete bandwidth attached SHOULD contain one or more Availability SCSI-TLVs in its OSPF-TE LSA messages 🫶. Each Availability SCSI-TLV tells you how much bandwidth a link can support for a specific availability. This info may be used for path calculation by the node(s) 🧮.

The Availability SCSI-TLV MUST NOT be sent in ISCDs with Switching Capability field values that haven't been defined to support it. Non-supporting nodes would treat that ISCD/LSA as malformed 💀.

If the Availability SCSI-TLV is missing from an ISCD with Switching Capability field values that have been defined to support it, that SHALL be interpreted as the fixed-bandwidth link with the highest availability value 👑.

Only one Availability SCSI-TLV for a specific availability level SHOULD be sent 🙈. If multiple TLVs are present, the Availability SCSI-TLV with the lowest bandwidth value SHALL be processed 🔍. If an Availability SCSI-TLV has an invalid value (for example, larger than 1), it will be ignored 🚫.

That's the spec body, bestie 🧚. Part 2 is coming with Security Considerations, IANA Considerations, the references, Acknowledgments, and the Authors' Addresses 🌈💜

5. Security Considerations 🔒✨

okay bestie, this section is lowkey serious but still so important 💅 This document is about the contents of Opaque LSAs in OSPFv2. Tampering with GMPLS-TE LSAs can mess with TE computations, which is NOT the vibe 😭 [RFC3630] suggests mechanisms like the one in [RFC2154] to protect the transmission of this info, and those or other mechanisms should be used to secure and/or authenticate the information carried in the Opaque LSAs 🛡️ An analysis of OSPF security is in [RFC6863], and it applies to the OSPF extension defined in this document 🧐 Any new mechanism developed to protect info carried in Opaque LSAs will also automatically protect the extension defined here, which is giving protected-by-default energy 🌈

Also, if you want the full tea on security threats, defensive techniques, monitoring, detection, reporting of attacks, and requirements, check out [RFC5920] 🍓

6. IANA Considerations 🧚

Okay so this document introduces a new type of Generalized SCSI-TLV called Availability, which gets carried in the OSPF-TE LSA messages ✨ Technology-specific documents will reference this document to describe how the Availability SCSI-TLV gets used 💖

IANA created a registry called the "Generalized SCSI (Switching Capability Specific Information) TLV Types" registry [RFC8258]. It has been updated to include the following Availability SCSI-TLV 🎀

   Type     Description    Switching Type   Reference
   ------   ------------   --------------   ---------
   0x000A   Availability   5, 52            RFC 8330

New switching types are required in order to use the Availability SCSI-TLV 👑 IANA has registered the following in the "Switching Types" registry:

  Value  Name                       Reference
  -----  -------------------------- ---------
      5  PSC with GSCSI support     RFC 8330
     52  L2SC with GSCSI support    RFC 8330

7. References 📚

7.1. Normative References 💜

[IEEE754-2008]
           IEEE, "IEEE Standard for Floating-Point Arithmetic",
           IEEE 754-2008, DOI 10.1109/IEEESTD.2008.4610935.

[RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
           Requirement Levels", BCP 14, RFC 2119,
           DOI 10.17487/RFC2119, March 1997,
           <https://www.rfc-editor.org/info/rfc2119>.

[RFC4202]  Kompella, K., Ed., and Y. Rekhter, Ed., "Routing
           Extensions in Support of Generalized Multi-Protocol Label
           Switching (GMPLS)", RFC 4202, DOI 10.17487/RFC4202,
           October 2005, <https://www.rfc-editor.org/info/rfc4202>.

[RFC4203]  Kompella, K., Ed., and Y. Rekhter, Ed., "OSPF Extensions
           in Support of Generalized Multi-Protocol Label Switching
           (GMPLS)", RFC 4203, DOI 10.17487/RFC4203, October 2005,
           <https://www.rfc-editor.org/info/rfc4203>.

[RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in
           RFC 2119 Key Words", BCP 14, RFC 8174,
           DOI 10.17487/RFC8174, May 2017,
           <https://www.rfc-editor.org/info/rfc8174>.

[RFC8258]  Ceccarelli, D. and L. Berger, "Generalized SCSI: A Generic
           Structure for Interface Switching Capability Descriptor
           (ISCD) Switching Capability Specific Information (SCSI)",
           RFC 8258, DOI 10.17487/RFC8258, October 2017,
           <https://www.rfc-editor.org/info/rfc8258>.

7.2. Informative References 🦋

[F.1703]   International Telecommunication Union, "Availability
           objectives for real digital fixed wireless links used in
           27 500 km hypothetical reference paths and connections",
           ITU-R Recommendation F.1703-0, January 2005,
           <https://www.itu.int/rec/R-REC-F.1703-0-200501-I/en>.

[G.827]    International Telecommunication Union, "Availability
           performance parameters and objectives for end-to-end
           international constant bit-rate digital paths", ITU-T
           Recommendation G.827, September 2003,
           <https://www.itu.int/rec/T-REC-G.827/en>.

[P.530]    International Telecommunication Union, "Propagation data
           and prediction methods required for the design of
           terrestrial line-of-sight systems", ITU-R
           Recommendation P.530-17, December 2017,
           <https://www.itu.int/rec/R-REC-P.530/en>.

[RFC2154]  Murphy, S., Badger, M., and B. Wellington, "OSPF with
           Digital Signatures", RFC 2154, DOI 10.17487/RFC2154,
           June 1997, <https://www.rfc-editor.org/info/rfc2154>.

[RFC3630]  Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering
           (TE) Extensions to OSPF Version 2", RFC 3630,
           DOI 10.17487/RFC3630, September 2003,
           <https://www.rfc-editor.org/info/rfc3630>.

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

[RFC6863]  Hartman, S. and D. Zhang, "Analysis of OSPF Security
           According to the Keying and Authentication for Routing
           Protocols (KARP) Design Guide", RFC 6863,
           DOI 10.17487/RFC6863, March 2013,
           <https://www.rfc-editor.org/info/rfc6863>.

[RSVP-TE-Availability]
           Long, H., Ye, M., Mirsky, G., D'Alessandro, A., and H.
           Shah, "Ethernet Traffic Parameters with Availability
           Information", Work in Progress, draft-ietf-ccamp-rsvp-te-
           bandwidth-availability-08, January 2018.

Acknowledgments 🫶

The authors would like to thank Acee Lindem, Daniele Ceccarelli, and Lou Berger for their comments on the document 💕

Authors' Addresses 🎀

Hao Long
Huawei Technologies Co., Ltd.
No. 1899, Xiyuan Avenue, Hi-tech Western District
Chengdu  611731
China

Phone: +86-18615778750
Email: longhao@huawei.com


Min Ye
Huawei Technologies Co., Ltd.
No. 1899, Xiyuan Avenue, Hi-tech Western District
Chengdu  611731
China

Email: amy.yemin@huawei.com


Greg Mirsky
ZTE

Email: gregimirsky@gmail.com


Alessandro D'Alessandro
Telecom Italia S.p.A.

Email: alessandro.dalessandro@telecomitalia.it


Himanshu Shah
Ciena Corp.
3939 North First Street
San Jose, CA  95134
United States of America

Email: hshah@ciena.com

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