rfc8978v10.txt   rfc8978.txt 
Internet Engineering Task Force (IETF) F. Gont Internet Engineering Task Force (IETF) F. Gont
Request for Comments: 8978 SI6 Networks Request for Comments: 8978 SI6 Networks
Category: Informational J. Žorž Category: Informational J. Žorž
ISSN: 2070-1721 6connect ISSN: 2070-1721 6connect
R. Patterson R. Patterson
Sky UK Sky UK
February 2021 March 2021
Reaction of IPv6 Stateless Address Autoconfiguration (SLAAC) to Flash- Reaction of IPv6 Stateless Address Autoconfiguration (SLAAC) to Flash-
Renumbering Events Renumbering Events
Abstract Abstract
In scenarios where network configuration information related to IPv6 In scenarios where network configuration information related to IPv6
prefixes becomes invalid without any explicit and reliable signaling prefixes becomes invalid without any explicit and reliable signaling
of that condition (such as when a Customer Edge router crashes and of that condition (such as when a Customer Edge router crashes and
reboots without knowledge of the previously employed prefixes), hosts reboots without knowledge of the previously employed prefixes), hosts
skipping to change at line 245 skipping to change at line 245
of these prefixes to other internal network devices. Unless the of these prefixes to other internal network devices. Unless the
associated lease databases are stored on non-volatile memory, associated lease databases are stored on non-volatile memory,
these internal devices might get leased dynamic sub-prefixes of these internal devices might get leased dynamic sub-prefixes of
the stable prefix leased by the ISP. In other words, every time a the stable prefix leased by the ISP. In other words, every time a
prefix is leased, there is the potential for the resulting prefix is leased, there is the potential for the resulting
prefixes to become dynamic, even if the device leasing sub- prefixes to become dynamic, even if the device leasing sub-
prefixes has been leased a stable prefix by its upstream router. prefixes has been leased a stable prefix by its upstream router.
* While there is a range of information that may be employed to * While there is a range of information that may be employed to
correlate network activity [RFC7721], the use of stable prefixes correlate network activity [RFC7721], the use of stable prefixes
clearly simplifies network activity correlation and could reduce clearly simplifies network activity correlation and may reduce the
the effectiveness of "temporary addresses" [RFC4941]. effectiveness of "temporary addresses" [RFC8981].
* There might be existing advice for ISPs to deliver dynamic IPv6 * There might be existing advice for ISPs to deliver dynamic IPv6
prefixes *by default* (e.g., see [GERMAN-DP]) over privacy prefixes *by default* (e.g., see [GERMAN-DP]) over privacy
concerns associated with stable prefixes. concerns associated with stable prefixes.
* There might be scalability and performance drawbacks of either a * There might be scalability and performance drawbacks of either a
disaggregated distributed routing topology or a centralized disaggregated distributed routing topology or a centralized
topology, which are often required to provide stable prefixes, topology, which are often required to provide stable prefixes,
i.e., distributing more-specific routes or summarizing routes at i.e., distributing more-specific routes or summarizing routes at
centralized locations. centralized locations.
skipping to change at line 435 skipping to change at line 435
that while the values suggested in this section are an improvement that while the values suggested in this section are an improvement
over the default values specified in [RFC4861], they represent a over the default values specified in [RFC4861], they represent a
trade-off among a number of factors, including responsiveness, trade-off among a number of factors, including responsiveness,
possible impact on the battery life of connected devices possible impact on the battery life of connected devices
[RFC7772], etc. Thus, they may or may not provide sufficient [RFC7772], etc. Thus, they may or may not provide sufficient
mitigation to the problem discussed in this document. mitigation to the problem discussed in this document.
4. Future Work 4. Future Work
Improvements in Customer Edge routers [RFC7084], such that they can Improvements in Customer Edge routers [RFC7084], such that they can
signal hosts about stale prefixes to depreacte (and eventually signal hosts about stale prefixes to deprecate (and eventually
invalidate) them accordingly, can help mitigate the problem discussed invalidate) them accordingly, can help mitigate the problem discussed
in this document for the "home network" scenario. Such work is in this document for the "home network" scenario. Such work is
currently being pursued in [RENUM-CPE]. currently being pursued in [RENUM-CPE].
Improvements in the SLAAC protocol [RFC4862] and some IPv6-related Improvements in the SLAAC protocol [RFC4862] and some IPv6-related
algorithms, such as "Default Address Selection for Internet Protocol algorithms, such as "Default Address Selection for Internet Protocol
Version 6 (IPv6)" [RFC6724], would help improve network robustness. Version 6 (IPv6)" [RFC6724], would help improve network robustness.
Such work is currently being pursued in [RENUM-RXN]. Such work is currently being pursued in [RENUM-RXN].
The aforementioned work is considered out of the scope of this The aforementioned work is considered out of the scope of this
skipping to change at line 506 skipping to change at line 506
linkova-6man-default-addr-selection-update-00, 30 March linkova-6man-default-addr-selection-update-00, 30 March
2017, <https://tools.ietf.org/html/draft-linkova-6man- 2017, <https://tools.ietf.org/html/draft-linkova-6man-
default-addr-selection-update-00>. default-addr-selection-update-00>.
[FRITZ] Gont, F., "Quiz: Weird IPv6 Traffic on the Local Network [FRITZ] Gont, F., "Quiz: Weird IPv6 Traffic on the Local Network
(updated with solution)", SI6 Networks, February 2016, (updated with solution)", SI6 Networks, February 2016,
<https://www.si6networks.com/2016/02/16/quiz-weird-ipv6- <https://www.si6networks.com/2016/02/16/quiz-weird-ipv6-
traffic-on-the-local-network-updated-with-solution/>. traffic-on-the-local-network-updated-with-solution/>.
[GERMAN-DP] [GERMAN-DP]
BFDI, "Einführung von IPv6 Hinweise für Provider im BFDI, "Einführung von IPv6: Hinweise für Provider im
Privatkundengeschäft und Hersteller" [Introduction of Privatkundengeschäft und Hersteller" [Introduction of
IPv6: Notes for providers in the private sector and IPv6: Notes for providers in the consumer market and
manufacturers], Entschliessung der 84. Konferenz der manufacturers], Entschliessung der 84. Konferenz der
Datenschutzbeauftragten des Bundes und der Lander Datenschutzbeauftragten des Bundes und der Lander
[Resolution of the 84th Conference of the Federal and [Resolution of the 84th Conference of the Federal and
State Data Protection Commissioners], November 2012, State Commissioners for Data Protection], November 2012,
<http://www.bfdi.bund.de/SharedDocs/Publikationen/ <http://www.bfdi.bund.de/SharedDocs/Publikationen/
Entschliessungssammlung/DSBundLaender/84DSK_EinfuehrungIPv Entschliessungssammlung/DSBundLaender/84DSK_EinfuehrungIPv
6.pdf?__blob=publicationFile>. 6.pdf?__blob=publicationFile>.
[Linux-update] [Linux-update]
Gont, F., "Subject: [net-next] ipv6: Honor all IPv6 PIO Gont, F., "Subject: [net-next] ipv6: Honor all IPv6 PIO
Valid Lifetime values", message to the netdev mailing Valid Lifetime values", message to the netdev mailing
list, 19 April 2020, list, 19 April 2020,
<https://patchwork.ozlabs.org/project/netdev/ <https://patchwork.ozlabs.org/project/netdev/
patch/20200419122457.GA971@archlinux- patch/20200419122457.GA971@archlinux-
skipping to change at line 541 skipping to change at line 541
renum-07>. renum-07>.
[RENUM-RXN] [RENUM-RXN]
Gont, F., Zorz, J., and R. Patterson, "Improving the Gont, F., Zorz, J., and R. Patterson, "Improving the
Robustness of Stateless Address Autoconfiguration (SLAAC) Robustness of Stateless Address Autoconfiguration (SLAAC)
to Flash Renumbering Events", Work in Progress, Internet- to Flash Renumbering Events", Work in Progress, Internet-
Draft, draft-ietf-6man-slaac-renum-02, 19 January 2021, Draft, draft-ietf-6man-slaac-renum-02, 19 January 2021,
<https://tools.ietf.org/html/draft-ietf-6man-slaac-renum- <https://tools.ietf.org/html/draft-ietf-6man-slaac-renum-
02>. 02>.
[RFC4941] Narten, T., Draves, R., and S. Krishnan, "Privacy
Extensions for Stateless Address Autoconfiguration in
IPv6", RFC 4941, DOI 10.17487/RFC4941, September 2007,
<https://www.rfc-editor.org/info/rfc4941>.
[RFC7084] Singh, H., Beebee, W., Donley, C., and B. Stark, "Basic [RFC7084] Singh, H., Beebee, W., Donley, C., and B. Stark, "Basic
Requirements for IPv6 Customer Edge Routers", RFC 7084, Requirements for IPv6 Customer Edge Routers", RFC 7084,
DOI 10.17487/RFC7084, November 2013, DOI 10.17487/RFC7084, November 2013,
<https://www.rfc-editor.org/info/rfc7084>. <https://www.rfc-editor.org/info/rfc7084>.
[RFC7721] Cooper, A., Gont, F., and D. Thaler, "Security and Privacy [RFC7721] Cooper, A., Gont, F., and D. Thaler, "Security and Privacy
Considerations for IPv6 Address Generation Mechanisms", Considerations for IPv6 Address Generation Mechanisms",
RFC 7721, DOI 10.17487/RFC7721, March 2016, RFC 7721, DOI 10.17487/RFC7721, March 2016,
<https://www.rfc-editor.org/info/rfc7721>. <https://www.rfc-editor.org/info/rfc7721>.
[RFC7772] Yourtchenko, A. and L. Colitti, "Reducing Energy [RFC7772] Yourtchenko, A. and L. Colitti, "Reducing Energy
Consumption of Router Advertisements", BCP 202, RFC 7772, Consumption of Router Advertisements", BCP 202, RFC 7772,
DOI 10.17487/RFC7772, February 2016, DOI 10.17487/RFC7772, February 2016,
<https://www.rfc-editor.org/info/rfc7772>. <https://www.rfc-editor.org/info/rfc7772>.
[RFC8981] Gont, F., Krishnan, S., Narten, T., and R. Draves,
"Temporary Address Extensions for Stateless Address
Autoconfiguration in IPv6", RFC 8981,
DOI 10.17487/RFC8981, February 2021,
<https://www.rfc-editor.org/info/rfc8981>.
[RIPE-690] Žorž, J., Steffann, S., Dražumerič, P., Townsley, M., [RIPE-690] Žorž, J., Steffann, S., Dražumerič, P., Townsley, M.,
Alston, A., Doering, G., Palet Martinez, J., Linkova, J., Alston, A., Doering, G., Palet Martinez, J., Linkova, J.,
Balbinot, L., Meynell, K., and L. Howard, "Best Current Balbinot, L., Meynell, K., and L. Howard, "Best Current
Operational Practice for Operators: IPv6 prefix assignment Operational Practice for Operators: IPv6 prefix assignment
for end-users - persistent vs non-persistent, and what for end-users - persistent vs non-persistent, and what
size to choose", RIPE 690, October 2017, size to choose", RIPE 690, October 2017,
<https://www.ripe.net/publications/docs/ripe-690>. <https://www.ripe.net/publications/docs/ripe-690>.
[UK-NOF] Palet Martinez, J., "IPv6 Deployment Survey and BCOP", UK [UK-NOF] Palet Martinez, J., "IPv6 Deployment Survey and BCOP", UK
NOF 39, January 2018, NOF 39, January 2018,
 End of changes. 8 change blocks. 
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