RFC 8191
Home Network Prefix Renumbering in Proxy Mobile IPv6 (PMIPv6)
Home Network Prefix Renumbering in Proxy Mobile IPv6 (PMIPv6) 🎀
- RFC: 8191 📜
- Title: Home Network Prefix Renumbering in Proxy Mobile IPv6 (PMIPv6) 🌸
- Authors: Z. Yan (CNNIC), J. Lee (Sangmyung University), X. Lee (CNNIC) 👯
- Category: Standards Track 🦋
- Date: August 2017 📅
- ISSN: 2070-1721
- Publisher: the Internet Engineering Task Force (IETF) 🌈
- Obsoletes / Updates: this one doesn't list any RFCs it obsoletes or updates, so it doesn't replace or change any earlier RFC 🙅♀️
Abstract ✨
Okay so, in basic Proxy Mobile IPv6 (PMIPv6), a Mobile Node (MN) gets a Home Network Prefix (HNP) when it first attaches, and it sets up its Home Address (HoA) using that HNP. While the MN is moving around, the HNP stays the same so the ongoing chats tied to the HoA don't break 🦋. The catch is that the current PMIPv6 spec doesn't say what to do when HNP renumbering happens (like when the service provider changes, or the site topology gets reshuffled, etc.) 😭. So this doc proposes a way to support HNP renumbering, as an optional extension of the PMIPv6 spec. Iconic behavior 💅.
Status of This Memo 📌
This is an Internet Standards Track document 🔥.
It's a product of the Internet Engineering Task Force (IETF) and 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 on Internet Standards, check Section 2 of RFC 7841 🧚.
For the current status, any errata, and how to send feedback, go to http://www.rfc-editor.org/info/rfc8191 🔗.
Copyright Notice 💜
Copyright (c) 2017 IETF Trust and the persons identified as the document authors. All rights reserved 🌸.
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) as they stand on the publication date. Please actually read these, bestie, because they spell out your rights and restrictions for this document 🙈. Code Components pulled out of this document must include the Simplified BSD License text, as described in Section 4.e of the Trust Legal Provisions, and they come with no warranty, as described in the Simplified BSD License ⚠️.
Table of Contents 🗂️
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Usage Scenarios . . . . . . . . . . . . . . . . . . . . . . . 3
3. HNP Renumbering Procedure . . . . . . . . . . . . . . . . . . 4
4. Session Connectivity . . . . . . . . . . . . . . . . . . . . 6
5. Message Format . . . . . . . . . . . . . . . . . . . . . . . 6
6. Other Issues . . . . . . . . . . . . . . . . . . . . . . . . 7
7. Security Considerations . . . . . . . . . . . . . . . . . . . 7
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
9.1. Normative References . . . . . . . . . . . . . . . . . . 8
9.2. Informative References . . . . . . . . . . . . . . . . . 9
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 101. Introduction 🌷
Right now, network managers like Provider-Independent (PI) addressing for IPv6, because it helps them dodge future renumbering 🙃. The problem is that lots of PI addresses cause Border Gateway Protocol (BGP) scaling problems [RFC7010]. So it's way better to build tools and practices that make IPv6 renumbering simpler, which cuts down on demand for IPv6 PI space [RFC6879]. This doc is all about supporting HNP renumbering when the HNP in PMIPv6 [RFC5213] is not a PI prefix. Main character energy 👑.
1.1. Requirements Language 🔑
Okay, 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 read as described in BCP 14 [RFC2119] [RFC8174], but only when they show up in all capitals, exactly like that 💖. Otherwise they're just regular words 🧚.
2. Usage Scenarios 🦋
There are a bunch of reasons why HNP renumbering support in PMIPv6 is useful, so here are some scenarios 🍓:
- Scenario 1: the HNP set used by a PMIPv6 service provider is assigned by a different Internet Service Provider (ISP). Then HNP renumbering MAY occur if the PMIPv6 service provider switches to a different ISP 🌈.
- Scenario 2: multiple Local Mobility Anchors (LMAs) MAY be deployed by the same PMIPv6 service provider, and then each LMA MAY serve for a specific HNP set. In this case, the HNP of an MN MAY change if the serving LMA is changed to another LMA that does not inherit the assigned HNP set [RFC6463] 👀.
- Scenario 3: PMIPv6 HNP renumbering MAY be caused by the rebuilding of the network architecture as the companies split, merge, grow, relocate, or reorganize. For example, the PMIPv6 service provider MAY reorganize its network topology 🏗️.
In Scenario 1, we assume that only the HNP gets renumbered while the serving LMA stays the same. This is the basic scenario this document focuses on ✨. In Scenarios 2 and 3, things get more complicated, and HNP renumbering MAY result from more complex situations. For example, HNP renumbering MAY occur because the serving LMA switched over 🌀.
In Mobile IPv6 (MIPv6), when an HNP changes, the Home Agent (HA) actively tells its MN about the new prefix, so renumbering the Home Network Address (HoA) is well supported [RFC6275] 💜. In basic PMIPv6, the PMIPv6 binding gets triggered by a Mobile Access Gateway (MAG) when it notices the MN attaching 📡. The LMA also needs a way to immediately kick off a refresh of the PMIPv6 binding state during HNP renumbering. This was mentioned in Section 6.12 of [RFC5213], but the actual solution was never specified 😤.
3. HNP Renumbering Procedure 🎀
When HNP renumbering happens in PMIPv6, the LMA MUST notify the MAG about the new HNP, and then the MAG MUST announce the new HNP to the attached MN. Also, the LMA and the MAG MUST update the routing states for the HNP and the related addresses. To make this work, [RFC7077] can be adopted, since it specifies an asynchronous update from the LMA to the MAG about specific session parameters 💅. This document looks at the following two cases:
(1) HNP is renumbered under the same LMA
In this case, the LMA stays the same, like in Scenarios 1 and 3. The steps are shown in Figure 1 🦋.
+-----+ +-----+ +-----+
| MN | | MAG | | LMA |
+-----+ +-----+ +-----+
| | |
| | Allocate new HNP
| | |
| |<------------- UPN ---|
| | |
| | |
| | |
|<-----RA/DHCP --------| |
| | |
Address configuration | |
| | |
| Update binding & routing states |
| | |
| |--- UPA ------------->|
| | |
| | Update binding & routing states
| | |Figure 1: Signaling Call Flow for HNP Renumbering 🌸
- Okay, when a PMIPv6 service provider renumbers the HNP set under the same LMA, the serving LMA SHOULD initiate the HNP renumbering operation. The LMA allocates a new HNP for the related MN 🧚.
- The LMA sends the Update Notification (UPN) message to the MAG to update the HNP information. If the Dynamic Host Configuration Protocol (DHCP) is used to allocate the address, the DHCP infrastructure MUST also be notified about the new HNP 📬.
- Once the MAG gets this UPN message, it knows the related MN has the new HNP. Then the MAG MUST notify the MN about the new HNP with a Router Advertisement (RA) message, or allocate a new address within the new HNP through a DHCP procedure 📣.
- After the MN gets the HNP information through the RA message, it deletes the old HoA and configures a new HoA with the newly allocated HNP 🔄.
- When the new HNP is announced or the new address is configured on the MN successfully, the MAG MUST update the related binding and routing states. Then the MAG sends back the Update Notification Acknowledgement (UPA) message to the LMA, to say the HNP, related binding state, and routing state were updated successfully. After that, the LMA updates the routing and binding info for the MN so the new HNP replaces the old one 🥳.
(2) HNP renumbering is caused by the LMA switchover
Since the HNP is assigned by the LMA, HNP renumbering MAY be caused by the LMA switchover, like in Scenarios 2 and 3 🌀.
The LMA information is the basic configuration info of the MAG. When the LMA changes, the related profile SHOULD be updated by the service provider. That way, the MAG starts the binding registration to the MN's new LMA as specified in [RFC5213]. When HNP renumbering happens in this case, the new HNP info is sent by the LMA during the new binding procedure. So the MAG withdraws the MN's old HNP and announces the new HNP to the MN, similar to when the HNP is renumbered under the same LMA 💖.
4. Session Connectivity 📡
HNP renumbering MAY cause the MN's ongoing communications to disconnect. Basically, there are two modes for managing session connectivity during HNP renumbering 🙈.
(1) Soft mode
The LMA temporarily keeps the state of the old HNP during HNP renumbering (after the UPA reception). This lets it redirect packets to the MN before the MN reconnects the ongoing session and tells the Correspondent Node (CN) about its new HoA. The goal is to cut down on packet loss during HNP renumbering. The binding state for the old HNP SHOULD be marked, for example, as transient binding [RFC6058]. Also, the LMA MUST stop broadcasting routing info about the old HNP if the old HNP is no longer anchored at this LMA 🫶.
(2) Hard mode
If HNP renumbering happens with an LMA switchover, hard mode is RECOMMENDED because it keeps the protocol simple 🔥. In this mode, the LMA deletes the binding state of the old HNP after it receives the UPA message from the MAG, and then the LMA silently discards any packets destined for the old HNP 💀.
Part 1 is done! Part 2 picks up with Section 5 (Message Format) and everything after it, so stay tuned, bestie 🧚💖
5. Message Format 🎀
okay so this is where the actual messages get their outfits 💅 there are four of them, and I'm gonna walk you through each one.
(1) UPN message 💌
In the UPN message the LMA sends to the MAG, the notification reason is set to 2 (UPDATE-SESSION-PARAMETERS). Then the HNP Option [RFC5213] carrying the new HNP and the Mobile Node Identifier Option [RFC4283] (which identifies the MN) both ride along as Mobility Options of the UPN. The order of the HNP Option and the Mobile Node Identifier Option in the UPN message is not mandated here, so you do you 🦋
(2) UPA message 🫶
The MAG sends this one to say "yep, got your UPN with the (A) flag set" and to report how things went after processing it. If the MAG did not successfully renumber the HNP that the UPN asked for, the UPA gets Status Code 128 (FAILED-TO-UPDATE-SESSION-PARAMETERS). What the LMA does next is PMIPv6 service provider specific, so that part is up to the provider 🤷♀️
(3) RA message 📡
When the MAG uses the RA message to advertise the new HNP, it includes two Prefix Information Options [RFC4861] [RFC4862]. The first one carries the old HNP, with its Preferred Lifetime set to 0. The second one carries the new HNP with a Valid Lifetime, and its Preferred Lifetime is set to something larger than 0 ✨ the old prefix gets deprecated and the new one gets to shine.
(4) DHCP message 🌸
When DHCP is used in PMIPv6 to configure addresses for the MN, new IPv6 address(es) (for example the HoA) get generated based on the new HNP. The related DHCP procedure is also triggered by receiving the UPN message [RFC3315]. the vibe is very "new prefix, new address, same girl" 💖
6. Other Issues 🧚
okay, one more thing 👀 to keep the MN reachable, the Domain Name System (DNS) resource record for this MN MAY need to be updated when the MN's HNP changes [RFC3007]. But that's beyond the scope of this document, so we're leaving it for another day 💅
7. Security Considerations 🔐
ngl this section is the big one, so pay attention bestie 😭
The UPN and UPA messages in this document MUST be protected using end-to-end security association(s) offering integrity and data origin authentication, as specified in [RFC5213] and [RFC7077]. No skipping this part, fr fr.
When HNP renumbering is triggered, a new HNP SHOULD be allocated to the MN. The LMA MUST follow the procedure of PMIPv6 to make sure that only an authorized HNP can be assigned for the MN. That way the LMA is ready to be the topological anchor point of the new HNP, which is for that MN's exclusive use. Main character energy, but make it secure 👑
Per [RFC4862], if the Valid Lifetime in a Prefix Information Option is set to less than 2 hours in an unauthenticated RA, it gets ignored. So when the old HNP being deprecated shows up in an RA from the MAG, the Valid Lifetime SHOULD be set to 2 hours (and the Preferred Lifetime set to 0) for that unauthenticated RA. However, if the legality of the signaling messages exchanged between the MAG and the MN can be guaranteed, it MAY be acceptable to also set the Valid Lifetime to 0 for an unauthenticated RA. Only do that if you can actually guarantee the signaling is legit 🙈
8. IANA Considerations 📋
This document does not require any IANA actions. Zero registry drama today 🎀
9. References 📚
9.1. Normative References
[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>.
[RFC3007] Wellington, B., "Secure Domain Name System (DNS) Dynamic
Update", RFC 3007, DOI 10.17487/RFC3007, November 2000,
<http://www.rfc-editor.org/info/rfc3007>.
[RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins,
C., and M. Carney, "Dynamic Host Configuration Protocol
for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July
2003, <http://www.rfc-editor.org/info/rfc3315>.
[RFC4283] Patel, A., Leung, K., Khalil, M., Akhtar, H., and K.
Chowdhury, "Mobile Node Identifier Option for Mobile IPv6
(MIPv6)", RFC 4283, DOI 10.17487/RFC4283, November 2005,
<http://www.rfc-editor.org/info/rfc4283>.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
DOI 10.17487/RFC4861, September 2007,
<http://www.rfc-editor.org/info/rfc4861>.
[RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
Address Autoconfiguration", RFC 4862,
DOI 10.17487/RFC4862, September 2007,
<http://www.rfc-editor.org/info/rfc4862>.
[RFC5213] Gundavelli, S., Ed., Leung, K., Devarapalli, V.,
Chowdhury, K., and B. Patil, "Proxy Mobile IPv6",
RFC 5213, DOI 10.17487/RFC5213, August 2008,
<http://www.rfc-editor.org/info/rfc5213>.
[RFC6275] Perkins, C., Ed., Johnson, D., and J. Arkko, "Mobility
Support in IPv6", RFC 6275, DOI 10.17487/RFC6275, July
2011, <http://www.rfc-editor.org/info/rfc6275>.
[RFC6463] Korhonen, J., Ed., Gundavelli, S., Yokota, H., and X. Cui,
"Runtime Local Mobility Anchor (LMA) Assignment Support
for Proxy Mobile IPv6", RFC 6463, DOI 10.17487/RFC6463,
February 2012, <http://www.rfc-editor.org/info/rfc6463>.
[RFC7077] Krishnan, S., Gundavelli, S., Liebsch, M., Yokota, H., and
J. Korhonen, "Update Notifications for Proxy Mobile IPv6",
RFC 7077, DOI 10.17487/RFC7077, November 2013,
<http://www.rfc-editor.org/info/rfc7077>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <http://www.rfc-editor.org/info/rfc8174>.9.2. Informative References
[RFC6058] Liebsch, M., Ed., Muhanna, A., and O. Blume, "Transient
Binding for Proxy Mobile IPv6", RFC 6058,
DOI 10.17487/RFC6058, March 2011,
<http://www.rfc-editor.org/info/rfc6058>.
[RFC6879] Jiang, S., Liu, B., and B. Carpenter, "IPv6 Enterprise
Network Renumbering Scenarios, Considerations, and
Methods", RFC 6879, DOI 10.17487/RFC6879, February 2013,
<http://www.rfc-editor.org/info/rfc6879>.
[RFC7010] Liu, B., Jiang, S., Carpenter, B., Venaas, S., and W.
George, "IPv6 Site Renumbering Gap Analysis", RFC 7010,
DOI 10.17487/RFC7010, September 2013,
<http://www.rfc-editor.org/info/rfc7010>.Acknowledgements 🫶
Big thanks to Jong-Hyouk Lee 💜 his work was supported by 'The Cross-Ministry Giga KOREA Project' grant from the Ministry of Science, ICT and Future Planning, Korea. Iconic support 🌈
Authors' Addresses 💌
Zhiwei Yan
CNNIC
No.4 South 4th Street, Zhongguancun
Beijing 100190
China
Email: yan@cnnic.cn
Jong-Hyouk Lee
Sangmyung University
31, Sangmyeongdae-gil, Dongnam-gu
Cheonan 31066
Republic of Korea
Email: jonghyouk@smu.ac.kr
Xiaodong Lee
CNNIC
No.4 South 4th Street, Zhongguancun
Beijing 100190
China
Email: xl@cnnic.cn📦 where this page comes from
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