Network Working Group Y. Liu
Internet-Draft China Mobile
Intended status: Informational D. Voyer
Expires: 13 August 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
12 February 2025
SRv6 Deployment and Operation Problem Summary
draft-liu-srv6ops-problem-summary-04
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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Internet-Draft SRv6 Deployment and Operation Problem Summary Feb 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. SRv6 and non-SRv6 network Coexistence and Transition.............6
8. SRv6 Traversing Third-Party Networks.............................6
9. Challenges of Different Network Types............................6
10. Security Considerations.........................................7
11. IANA Considerations.............................................7
12. References......................................................7
12.1. Normative References.......................................7
12.2. Informative References.....................................7
Authors' Addresses..................................................9
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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
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further work to deal with the challenges of SRv6 inter-domain
deployments including:
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.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
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performance, enhancing fault handling capabilities, ensuring
security, improving compatibility and interoperability, optimizing
management and monitoring, and enhancing deployment experience. Some
initial work could refer to [I-D.liu-srv6ops-sr-protection].
DOP-8 Deployment practices in operational scenarios of protection
in SRv6 networks.
7. SRv6 and non-SRv6 network Coexistence and Transition
To evolve an non-SRv6 network into an SRv6 network, take MPLS
network as an example, two scenarios need to be considered:
For SRv6 and MPLS coexistence, a smooth transition from an MPLS
network to an SRv6 network is required, avoiding service
interruptions. For instance, deploy dual-stack tunnels for VPN over
MPLS and VPN over SRv6, with MPLS and SRv6 sharing VPN instances.
When the next hop of the route is an IPv4 address, iterate through
the MPLS tunnel; when the next hop is an IPv6 address, iterate
through the SRv6 tunnel. Prefer VPN routes based on SRv6. Once the
transition is complete, remove the MPLS tunnel.
For SRv6 and MPLS integration, the legacy MPLS network and the newly
established SRv6 network coexist, ensuring intercommunication
between the two networks. For instance, configure route regeneration
and route re-advertisement functions between two address families
(EVPN, VPN) on edge nodes.
DOP-9 Achieving a smooth transition from non-SRv6 to SRv6 and
ensuring interoperability between MPLS and SRv6 networks.
8. SRv6 Traversing Third-Party Networks
In some cases, SRv6 needs to traverse third-party networks that may
not natively support SRv6. One of the possible methods is to
establish tunnels between nodes that support SRv6, and create SRv6
BE (Bandwidth Engineering) or SRv6 TE (Traffic Engineering) Policy
across the tunnels.
DOP-10 Effectively routing SRv6 traffic across third-party networks
that lack native SRv6 support.
9. Challenges of Different Network Types
SRv6 deployment faces various challenges across different network
environments, including not only carrier networks but also data
centers and enterprise-specific applications. For instance, in the
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power grid, SRv6 is supposed to provide Quality of Service (QoS)
guarantees, performance optimization, and other specialized features
to meet specific demands based on the power application scenario.
DOP-11 Ensuring effective SRv6 deployment across carrier, data
center, and industry networks, with a focus on QoS and performance.
10. Security Considerations
TBD.
11. IANA Considerations
This document makes no request of IANA.
Note to RFC Editor: this section may be removed on publication as an
RFC.
12. References
12.1. 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
12.2. Informative References
[I-D.liu-srv6ops-sid-address-assignment] Liu, Y. and Y. Zhu, "IPv6
Address Assignment for SRv6", Expired, 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.geng-srv6ops-traffic-steering-to-srv6] Geng, G. and Liu,
Y., "IPv6 Address Assignment for SRv6", Expired, Internet-
Draft, draft-geng-srv6ops-traffic-steering-to-srv6-00, 4
March 2024, <https://datatracker.ietf.org/doc/html/draft-
geng-srv6ops-traffic-steering-to-srv6-00>.
[I-D.liu-srv6ops-sr-protection] Liu, Y. and C. Lin, "Best
Practices for Protection of SR Networks", Expired,
Internet-Draft, draft-liu-srv6ops-sr-protection-02, 8 July
2024, <https://datatracker.ietf.org/doc/html/draft-liu-
srv6ops-sr-protection-02>.
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Authors' Addresses
Yisong Liu
China Mobile
Email: liuyisong@chinamobile.com
Daniel Voyer
Bell Canada
Email: Danvoyer@gmail.com
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
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Xinxin Yi
China Unicom
Email: yixx3@chinaunicom.cn
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