SRv6 Deployment and Operation Problem Summary
draft-liu-srv6ops-problem-summary-03

Network Working Group                                            Y. Liu
Internet-Draft                                             China Mobile
Intended status: Informational                                 D. Voyer
Expires: January 4, 2025                                    Bell Canada
                                                                T. Graf
                                                               Swisscom
                                                              Z. Miklos
                                                                    MTN
                                                           L. Contreras
                                                             Telefonica
                                                             N. Leymann
                                                       Deutsche Telekom
                                                                L. Song
                                                           Alibaba, Inc
                                                          S. Matsushima
                                                               SoftBank
                                                                 C. Xie
                                                          China Telecom
                                                                  X. Yi
                                                           China Unicom
                                                           July 5, 2024

               SRv6 Deployment and Operation Problem Summary
                    draft-liu-srv6ops-problem-summary-03

Abstract

   This document aims to provide a concise overview of the common
   problems encountered during SRv6 deployment and operation, which
   provides foundations for further work, including for example of
   potential solutions and best practices to navigate deployment.

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   This Internet-Draft will expire on January 4, 2025.

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Table of Contents

   1. Introduction.....................................................3
      1.1. Requirements Language.......................................3
   2. Simplified Inter-domain Implementation...........................3
   3. SRv6 Data Plane Visualization....................................4
      3.1. Leveraging Existing Frameworks with new parameters..........4
      3.2. Optimizing Network Analysis and Performance.................5
   4. IPv6 Address Assignment for SRv6.................................5
   5. Traffic steering to SRv6.........................................5
   6. Deployment Practice for SRv6 Protection..........................5
   7. Security Considerations..........................................6
   8. IANA Considerations..............................................6
   9. References.......................................................6
      9.1. Normative References........................................6
      9.2. Informative References......................................6
   Authors' Addresses..................................................8

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1. Introduction

   Segment Routing over IPv6 (SRv6) is a new technology that builds
   upon the existing IPv6 infrastructure to offer programmable data
   plane capabilities.  This allows for more granular control over
   traffic forwarding, enabling flexible and scalable network designs.
   While SRv6 presents numerous potential benefits, such as improved
   traffic engineering, optimized resource utilization, its deployment
   and operation come with certain challenges.

   This document aims to provide a concise overview of the common
   problems encountered during SRv6 deployment and operation, which
   provides foundations for further work, including for example
   potential solutions and best practices to navigate deployment . By
   understanding these challenges and exploring mitigation strategies,
   network administrators can make informed decisions when implementing
   and managing SRv6 networks.

   This document identifies a number of Deployment and Operation
   Problems (DOPs) that require additional work within IETF.

1.1. Requirements Language

   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. Simplified Inter-domain Implementation

   While traditional inter-domain implementations in service provider
   networks often rely on MPLS and leverage Option A.  Option A has
   scalability limitations and is complex to deploy and maintain.  The
   ASBR needs to manage the routing of all VPNs and create VPN
   instances for each VPN.  At the same time, it requests associating
   separate interfaces and corresponding VLANs for each inter-domain
   VPN. SRv6 presents an alternative approach with E2E inter-domain
   solution, potentially leading to simplification and improved
   scalability from the following 2 aspects: 1) SRv6naturally support
   end-to-end inter-domain by utilizing IPv6 route reachability; 2)
   IPv6 route aggregation reduces the number of SRv6 locators
   distribution for inter-domain deployment.  However it requests
   further work to deal with the challenges of SRv6 inter-domain
   deployments including:

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   DOP-1 How to deploy SRv6 inter-domain in the existing MPLS network,
   which requires consideration of existing mechanism and potential
   migration strategies.

   DOP-2 Utilizing SRv6 compression techniques in inter-domain scenario
   to further optimize bandwidth usage, which requires effective IPv6
   address planning and block allocation strategies to achieve optimal
   aggregation benefits.

   Also, protocol extension is out of scope and only implementation
   experience is considered to deal with these challenges.

   For management purposes, the controller sometimes needs to
   temporarily divert traffic from a specific forwarding path and then
   restore the path after a period of time. In this scenario, the
   controller can issue a shutdown operation to a specific path of the
   SR Policy on the device without removing the path. Subsequently,
   when restoration is needed, the controller can directly issue an
   "undo shutdown" operation to the specific path of the SR Policy.

3. SRv6 Data Plane Visualization

   Network visualization is a critical aspect for service providers,
   especially when implementing new technologies like SRv6.  It
   provides essential insights into network traffic flow, resource
   utilization, and potential performance bottlenecks.  Visualizing the
   SRv6 data plane requests further work in the aspects described next.

3.1. Leveraging Existing Frameworks with new parameters

   The existing IETF work on data collection formats can be leveraged
   for SRv6 data plane visualization.  Further work is necessary to
   define SRv6-specific customization information; For example:

   DOP-3 Reuse Telemetry Framework: The telemetry framework, used for
   collecting and transmitting network telemetry data, offers a solid
   foundation.  While specific content and parameters need to be
   defined to capture SRv6-specific information relevant for
   visualization.

   DOP-4 Reuse Netconf/Yang Framework: SRPING already defines the Yang
   Model for protocol extension; for better operation and maintenance
   of SRv6 network, the Yang Model for information collection, status
   notification, failure handling and recovery may also be required.

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3.2. Optimizing Network Analysis and Performance

   Once data is collected from network devices using the defined
   format, several techniques can be employed to utilize this
   information for network analysis and performance optimization for
   SRv6, especially traffic engineering.  This brings the need for:

   DOP-5 Identification of techniques for performance optimization in
   operational scenarios.

4. IPv6 Address Assignment for SRv6

   Existing IPv6 address planning approach ensures efficient address
   utilization and simplifies network management for IPv6 netowrk,
   which can't satisfy the SRv6 SID planning for service provider,
   especially considering the complexities introduced by advanced
   features like SRv6 compression.  Further work is requested
   including: SRv6 SID Block Assignment, SRv6 SID Assignment for P2P
   and P2MP, SRv6 Node ID Assignment, SRv6 Function ID Assignment and
   so on.  Some initial work could refer to [I-D.liu-srv6ops-sid-
   address-assignment].  In summary:

   DOP-6 Efficient assignment of addresses and identifiers.

5. Traffic steering to SRv6

   There are various SRv6 traffic steering methods, each with its own
   unique advantages and challenges. It is essential to choose the
   appropriate traffic steering method based on specific application
   scenarios to ensure efficient operation. This brings the need for:
   selecting the appropriate traffic steering method tailored to SRv6
   specific application scenarios and ensuring efficient execution.
   Some initial work could refer to [I-D. draft-geng-srv6ops-traffic-
   steering-to-srv6]. In summary:

   DOP-7 Efficient Traffic Steering to SRv6 Network.

6. Deployment Practice for SRv6 Protection

   Implementing reliability practices can significantly enhance the
   stability and performance of networks based on SRv6. Network
   failures are inevitable in the real world. Reliability practices can
   help network engineers quickly identify, isolate, and fix faults,
   thus minimizing impact on services.

   In summary, the necessity of SRv6 reliability practices is evident
   in several aspects, including improving network stability and
   performance, enhancing fault handling capabilities, ensuring

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   security, improving compatibility and interoperability, optimizing
   management and monitoring, and enhancing deployment experience. Some
   initial work could refer to [I-D.draft-liu-srv6ops-sr-protection].

   DOP-8  Deployment practices in operational scenarios of protection
   in SRv6 networks.

7. Security Considerations

   TBD.

8. IANA Considerations

   This document makes no request of IANA.

   Note to RFC Editor: this section may be removed on publication as an
   RFC.

9. References

9.1. Normative References

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

   [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
             2119 Key Words", BCP 14, RFC 8174, May 2017

9.2. Informative References

   [I-D.liu-srv6ops-sid-address-assignment] Liu, Y. and Y. Zhu, "IPv6
             Address Assignment for SRv6", Work in Progress, Internet-
             Draft, draft-liu-srv6ops-sid-address-assignment-00, 7
             February 2024,
             <https://datatracker.ietf.org/doc/html/draft-liu-srv6ops-
             sid-address-assignment-00>.

   [I-D. draft-geng-srv6ops-traffic-steering-to-srv6] Geng, G. and Liu,
             Y., "IPv6 Address Assignment for SRv6", Work in Progress,
             Internet-Draft, draft-geng-srv6ops-traffic-steering-to-
             srv6-00, 7 February 2024,
             <https://datatracker.ietf.org/doc/html/ draft-geng-
             srv6ops-traffic-steering-to-srv6-00>.

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   [I-D. draft-liu-srv6ops-sr-protection] Liu, Y. and C. Lin, "Best
             Practices for Protection of SR Networks", Work in
             Progress, Internet-Draft, draft-liu-srv6ops-sr-protection-
             01, 7 February 2024,
             <https://datatracker.ietf.org/doc/html/ draft-liu-srv6ops-
             sr-protection-01>.

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Authors' Addresses

   Yisong Liu
   China Mobile
   Email: liuyisong@chinamobile.com

   Daniel Voyer
   Bell Canada
   Email: daniel.voyer@bell.ca

   Thomas Graf
   Swisscom
   Email: Thomas.Graf@swisscom.com

   Zoltan Miklos
   MTN
   Email: Zoltan.Miklos@mtn.com

   Luis Contreras
   Telefonica
   Email: luismiguel.contrerasmurillo@telefonica.com

   Nicolai Leymann
   Deutsche Telekom
   Email: N.Leymann@telekom.de

   Linjian Song
   Alibaba, Inc
   Email: linjian.slj@alibaba-inc.com

   Satoru Matsushima
   SoftBank
   Email: satoru.matsushima@g.softbank.co.jp

   Chongfeng Xie
   China Telecom
   Email: xiechf@chinatelecom.cn

   Xinxin Yi

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   China Unicom
   Email: yixx3@chinaunicom.cn

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