RFC 6279
Proxy Mobile IPv6 (PMIPv6) Localized Routing Problem Statement
RFC 6279 🎀 Proxy Mobile IPv6 (PMIPv6) Localized Routing Problem Statement
Authors: M. Liebsch, Ed. (NEC), S. Jeong (ETRI), and Q. Wu (Huawei) 🫶 Category: Informational 📚 ISSN: 2070-1721 Date: June 2011 📅 Obsoletes / Updates: Its title block doesn't list any document that it obsoletes or updates. 🙅♀️
(Part 1 of 3 💖)
Abstract ✨
Okay so, Proxy Mobile IPv6 is the IETF Standard for network-based mobility management 🌸 In PMIPv6, mobile nodes are topologically anchored at a Local Mobility Anchor, and that LMA forwards all the data for its registered mobile nodes 🦋 Localized routing is the thing where data packets go straight between two mobile nodes' Mobility Access Gateways, without their Local Mobility Anchor being involved in the forwarding 💅 Setting that up and keeping it going is not covered by the spec, so this document is here to map out the problem space of localized routing in PMIPv6 🔥
Status of This Memo 📝
This document is not an Internet Standards Track specification. It's published for informational purposes, so no vibe-checking it as a standard 🧚
This document is a product of the Internet Engineering Task Force (IETF) 🌈 It represents the consensus of the IETF community and it got public review. It was approved for publication by the Internet Engineering Steering Group (IESG). Not every document the IESG approves is a candidate for any level of Internet Standard, so see Section 2 of RFC 5741 if you want the details 🤓
Want the latest on this document's status, any errata, or how to give feedback? Check http://www.rfc-editor.org/info/rfc6279 ✨
Copyright Notice ©️
Copyright (c) 2011 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, which are at http://trustee.ietf.org/license-info. They're the version in effect on the date this document was published, so please read them carefully, because they spell out your rights and restrictions for this document 📜 Code Components pulled out of this document must include Simplified BSD License text, as described in Section 4.e of the Trust Legal Provisions, and they come without warranty, as described in the Simplified BSD License 🫶
Table of Contents 🗂️
1. Introduction ....................................................2
2. Conventions and Terminology .....................................3
3. Problem Statement for Localized Routing in PMIPv6 ...............4
3.1. General Observation ........................................4
3.2. Use Cases Analysis .........................................5
3.3. IPv4 Considerations ........................................8
3.3.1. Localized Routing for Communication between
IPv4 Home Addresses .................................8
3.3.2. IPv4 Transport Network Considerations ...............9
4. Functional Requirements for Localized Routing ...................9
5. Roaming Considerations .........................................10
6. Security Considerations ........................................11
7. Acknowledgments ................................................12
8. References .....................................................13
8.1. Normative References ......................................13
8.2. Informative References ....................................131. Introduction 🌷
The IETF picked Proxy Mobile IPv6 (PMIPv6) [RFC5213] as the base protocol for network-based localized mobility management (NetLMM) 👑 The base protocol's scope covers setting up and maintaining a tunnel between a Mobile Node's (MN's) Mobile Access Gateway (MAG) and its selected Local Mobility Anchor (LMA) 🦋 Data packets always go through the MN's MAG and its LMA, no matter where the MN's remote communication endpoint is 😭 Even if an MN and its Correspondent Node (CN) are attached to the same MAG or to different MAGs within the same provider domain, the packets for that conversation still go through the MN's and the CN's LMA. That LMA can be topologically far away from the MN's and the CN's MAG, or even in a separate provider domain 💀
[RFC5213] deals with the need to enable local routing of traffic between two nodes attached to the same MAG, but it doesn't specify the full procedure for setting up that localized routing state on the shared MAG 🙈
The NetLMM Extensions (NetExt) Working Group wants to design a solution for localized routing in PMIPv6 🎯 That goal includes specifying the protocol messages and the associated protocol operation between PMIPv6 components. Those support setting up a direct routing path for data packets between the MN's and the CN's MAG, while both hosts keep getting mobility service under the PMIPv6 protocol [RFC5213] 💖 Because of localized routing, those packets get forwarded between the two associated MAGs without going through the MN's and the CN's LMA(s) ✨ If one or both nodes hand over to a different MAG, the localized routing protocol keeps the localized routing path alive 🔥 The relevant protocol interfaces may include the interface between associated MAGs, the one between a MAG and an LMA, and the one between LMAs 🧚 Setting up localized routing with CNs that aren't registered with a PMIPv6 network is out of scope for the NetExt solution and for this problem statement 🙅♀️
This document analyzes and discusses the problem space of always using the default route through two communicating mobile nodes' local mobility anchors 🌸 It also analyzes and describes the problem space of enabling localized routing in PMIPv6, taking different communication and mobility scenarios into account 🎀 Based on that analysis, it gives a list of key functional requirements that feed into the design of the protocol solution 👑
2. Conventions and Terminology 📖
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119] 💅
This document uses the terminology of [RFC5213] 🦋 On top of that, these terms are used in the context of this problem statement:
- Mobile Node (MN): A Mobile Node without IP mobility support, which is attached to a Mobile Access Gateway (MAG) and registered with a Local Mobility Anchor (LMA) according to the PMIPv6 specification [RFC5213] 🌷
- Correspondent Node (CN): A Correspondent Node according to its definition in [RFC3775], with or without IP mobility support. The CN is the communication peer of an MN that is attached to a MAG and registered with an LMA according to the PMIPv6 specification 💜
- Localized Routing: The result of signaling to set up routing states on relevant network entities, so that data packets can be forwarded between an MN and a CN. Both are attached to MAGs that share the same provider domain, and the MN's LMA and the CN's LMA aren't involved in the data forwarding 🫶
- Localized Routing States: Information for localized routing on relevant forwarding entities along the optimized data path between an MN and a CN. That info includes route entries and tunnel endpoints, and it may include more about the MN and the CN, like the communicating nodes' Mobile Node Identifier and their assigned Home Network Prefix 🧚
- Provider Domain: A network domain in which network components are administered by a single authority, e.g., the mobile operator 🌈
3. Problem Statement for Localized Routing in PMIPv6 🔍
3.1. General Observation ✨
The Mobile IPv6 (MIPv6) protocol [RFC3775] has built-in mechanisms for direct communication between an MN and a CN 🦋 Route optimization mechanisms in MIPv6 can't be directly applied in PMIPv6 😭 Following the PMIPv6 paradigm, MNs aren't involved in mobility signaling, so they can't do the signaling needed to set up localized routes 💀 Instead, the localized routing solution has to consider functions in the network to figure out whether a localized route should be used, and then control the setup and maintenance of the localized routing states accordingly, without any help from the MN or the CN 👑 When two nodes are attached to the PMIPv6 network infrastructure and each one is registered with an LMA, data packets between them always traverse the responsible LMA(s) 🙈 At least some deployments would benefit from having that communication localized, instead of having packets traverse the core network to the LMA(s) 💖 In this document's context, localized communication means offloading traffic from LMAs and setting up an optimized forwarding path between the two communication endpoints 🌸
Localized routing is understood in [RFC5213] as optimizing traffic between an MN and a CN that are attached to an access link connected to the same MAG 🎀 In that case, the MAG forwards traffic directly between the MN and the CN. This assumes the MAG is enabled to support this feature (the EnableMAGLocalRouting flag is set on the MAG) and that the MN's LMA enforces this optimization 🔥 [RFC5213] doesn't specify how an LMA can enforce optimization for that kind of local communication 🫶 Keeping local forwarding going between the MN and the regular IPv6 CN gets even more complicated when the MN hands over to a different MAG 😭 That use case isn't considered in the specification and is out of scope for this problem statement 💅 This document focuses on use cases where both the MN and the CN are within a PMIPv6 network and served by an LMA in a domain of LMAs 🧚
With localized routing, operators can offload traffic from LMAs and from the core network 🌈 Setting up a direct path between the MN's and the CN's MAG can be beneficial for a few reasons. First, by limiting the communication to the access nodes, the data traffic traversing the MAG - LMA path (network) can be reduced. This matters a lot, because the transport network between the access and the core is often the bottleneck in terms of costs and performance 💸 Second, there may be performance benefits for data flows between the MN and the CN in terms of delay and packet loss, especially when the MN and the CN are attached to the same MAG and the LMA is topologically far away from that MAG 🚀 Even when the MN and the CN are attached to different MAGs, there could be a benefit in limiting the communication to the access network only, instead of traversing the transport network to the LMA 🌷 Furthermore, offloading traffic from the LMA through localized routing can improve the LMA's scalability, since it's a bottleneck for traffic being forwarded by many MAGs 👑
3.2. Use Cases Analysis
okay so this problem statement is all about local chats between PMIPv6 managed nodes 💬, the ones hanging out at MAGs that share the same provider domain 🌸. We're gonna look at different use cases where there's more than one LMA in the picture, which is giving main character energy with multiple anchors 👑. Figure 1 shows a PMIPv6-based network with two mobility anchors. Per [RFC5213], the MN moves around inside the PMIPv6 domain built by its LMA and MAG 🦋. Same vibe for the CN, which moves inside the domain built by the CN's LMA and MAG. And the analysis doesn't assume whether the MN and CN share the same PMIPv6 domain or not 🫶.
Internet Backbone
: :
+------------------+
| |
+----+ +----+
|LMA1| |LMA2|
+----+ +----+
| |
| |
+----+------------------+----+
| |
+----+ +----+
|MAG1| |MAG2|
+----+ +----+
: : :
+---+ +---+ +---+
|MN | |CN1| |CN2|
+---+ +---+ +---+Figure 1: Reference Architecture for Localized Routing in PMIPv6
All "A" use cases below assume that both the MN and the CN are registered with an LMA according to the PMIPv6 protocol 💅. MAG1 is always treated as the MN's current Proxy Care-of Address, while the CN can be connected to the same MAG, a different MAG, or a different LMA than the MN. So these topological differences get labeled like this:
A[number of MAGs][number of LMAs]
A11 🌷: The MN and the CN (CN1) connect to the same MAG (MAG1) and are registered with the same LMA (LMA). The common MAG may forward data packets between the MN and the CN directly without forwarding any packet to the LMA. [RFC5213] addresses this use case, but does not specify the complete procedure to establish such localized routing state on the shared MAG.
A12 🧚: The MN and the CN (CN1) connect to the same MAG (MAG1) and are registered with different LMAs (LMA1 and LMA2). The common MAG may forward data packets between the MN and the CN directly without forwarding any packet to the LMAs. Following the policy of [RFC5213] and enforcement of the setup of a localized forwarding path, potential problems exist in the case where LMA1 and LMA2 differ in their policy to control the MAG 😭.
A21 🍓: The CN (CN2) connects to a different MAG (MAG2) than the MN (MAG1), but the MN and the CN are registered with the same LMA (LMA1). The result of localized routing should be the existence of routing information at MAG1 and MAG2, which allows direct forwarding of packets between the MN's MAG1 and the CN's MAG2. As LMA1 is the common anchor for the MN and the CN and maintains location information for both nodes, no major race condition and instability in updating the states for localized routing is expected ✨.
A22 🔥: The CN (CN2) connects to a different MAG (MAG2) and a different LMA (LMA2) than the MN (MAG1, LMA1). The result of localized routing should be the existence of routing information at MAG1 and MAG2, which allows direct forwarding of packets between the MN's MAG1 and the CN's MAG2. As the location information of the CN and the MN is maintained at different LMAs, both LMAs need to be involved in the procedure to set up localized routing. In the case of a handover of the MN and/or the CN to a different MAG, non-synchronized control of updating the states for localized routing may result in race conditions, superfluous signaling, and packet loss 💀.
The following list summarizes general problems with setting up and maintaining localized routing between an MN and a CN. In the context of this problem statement, the MN and the CN are always assumed to be registered at an LMA according to the PMIPv6 protocol [RFC5213] 🎀.
- MNs do not participate in mobility management and hence cannot perform binding registration at a CN on their own. Rather, entities in the network infrastructure must take over the role of MNs to set up and maintain a direct route. Accordingly, a solution for localized routing in PMIPv6 must specify protocol operation between relevant network components, such as between a MAG and an LMA, to enable localized routing for data traffic without traversing the MN's and the CN's LMA(s) 🦋.
- In the case where the MN and the CN are both registered with different LMAs according to the PMIPv6 protocol, relevant information for the setup of a localized routing path, such as the current MAG of the MN and the CN, is distributed between these LMAs. This may complicate the setup and stable maintenance of states enabling localized routing 🙈.
- In the case where localized routing between an MN and a CN has been successfully set up and both nodes move and attach to a new access router simultaneously, signaling the new location and maintenance of states for localized routing at relevant routers may run into a race condition situation. This can happen in the case where coordination of signaling for localized routing and provisioning of relevant state information is distributed between different network entities, e.g., different LMAs. In such a case, as a result of the MN's handover, updated information about the MN's location may arrive at the CN's previous MAG, while the CN has already moved to a new MAG. The same applies to the other direction, where the system may update the MN's previous MAG about the CN's new location, while the MN has moved to a new MAG in the meantime. The protocol solution must deal with such exceptional handover cases efficiently to avoid or resolve such problems 😤💖.
3.3. IPv4 Considerations
according to [RFC5844], the basic configuration requirements for supporting IPv4 in PMIPv6 are that LMAs and MAGs are both IPv4 and IPv6 enabled 🌈. Also, LMAs and MAGs must have a globally unique IPv6 address configured, irrespective of enabled support for IPv6 routing between these components. This requirement should also apply to configuration requirements of localized routing ✨.
Additional issues emerge when localized routing is considered for PMIPv6 with IPv4 support 👀. These can be sorted into two general groups: issues with localized routing between an MN's and a CN's IPv4 Home Addresses, and transport plane issues. The following subsections analyze these two groups 💅.
3.3.1. Localized Routing for Communication between IPv4 Home Addresses
In the case where an LMA and a MAG hold a registration to support IPv4 Home Address mobility for an MN, the MAG and the LMA must support appropriate encapsulation of IPv4 packets. To enable localized routing, the MN's MAG must encapsulate and forward routing path optimized packets to the CN's MAG and needs to ensure that the chosen encapsulation mode is supported by the correspondent MAG. Incompatibility in a selected encapsulation mode causes failure in setting up a localized route 😭.
When localized routing is used for IPv4 traffic, the conceptual data structures on associated MAGs must be augmented with appropriate parameters for forwarding localized traffic. MAGs may need to maintain a routing state for each MN-CN-pair and make routing decisions for uplink traffic based on the packet's complete IPv4 source and destination address. Hence, conceptual data structures to handle states for localized routes need to comprise this address tuple for unique identification 🔥.
As a known constraint, IPv4 addresses of two nodes that hold addresses from a private address space may overlap. To uniquely identify both nodes, the IPv4 address of the MN and the CN must not overlap. To cope with overlapping address spaces, the localized routing solution could use additional mechanisms to tag and uniquely identify the MN and the CN 🧚.
3.3.2. IPv4 Transport Network Considerations
The transport network between the LMA and the MAG may be based on IPv6 or IPv4. Deployments may ensure that the same transport mechanism (i.e., IPv6 or IPv4) is used for operational consistency 🦋. Similar to the encapsulation requirement stated in the previous section, the IP version used for localized routing is also assumed, by configuration, to be consistent across all MAGs within the associated provider domain. The design of optional mechanisms for negotiating the IP version to use as well as the encapsulation mode to use are outside the scope of the NetExt WG's solution for localized routing 🌸.
4. Functional Requirements for Localized Routing ✨
Several tasks need to be performed by the network infrastructure components before relevant information for such direct communication is discovered and associated states for localized routing can be set up 💖. The following list summarizes some key functions that need to be performed by the PMIPv6-enabled network infrastructure to substitute mobile nodes in setting up a direct route.
- Detection of the possibility to perform localized routing. This function includes looking at a data packet's source and destination address 👀.
- Initiation of a procedure that sets up a localized routing path.
- Discovery of stateful entities (i.e., the LMA(s) and/or the MAG(s)) that maintain and can provide relevant information needed to set up a localized routing path. Such information may include the routable address of an LMA or MAG, where one or both mobile nodes are connected to and registered with that LMA or MAG 🔍.
- Control in setting up and maintaining (e.g., during handover) the localized routing path. Control is also needed to terminate the use of a localized routing path and to delete associated states, whereas a trigger for the termination may come from a non-PMIPv6-related component 🫶.
- Enforcement of administrative policy rules to localized routing. Such policies allow operators to have further control of the setup of a localized route and enable the possibility to disallow localized routing, for example, to ensure that traffic traverses charging-related functions on the LMA. Explicit authorization of localized routing is, for example, discussed in [PMIP6-LR]. As a further example, mobile-node- and operator-specific policy rules can be established on PMIPv6 components during PMIPv6 bootstrapping according to [RFC5779] 💅🌈.
5. Roaming Considerations 🌍
okay so Figure 2 shows the PMIPv6 roaming cases, where the PMIPv6 pieces (like LMAs and MAGs) tied to the MN and CN can be spread across different provider domains (domain A, B, and C), and the MN and/or CN can hop from one provider domain to another. 🦋 To support localized routing when roaming happens, it is required that the MAGs the MN and CN connect to be in the same provider domain, and that each MAG has a security relationship with the corresponding LMA that holds the registration for the MN or the CN, respectively. ✨
based on the roaming model in Figure 2, the MN's PMIPv6 domain is made up of its MAG (MAG1/MAG1') and its LMA (LMA1), while the CN's PMIPv6 domain is made up of the CN's MAG (MAG2/MAG2') and its LMA (LMA2/LMA2'). 💅 a solution for localized routing cannot assume whether or not the MN and CN share the same PMIPv6 domain, so MAG1/MAG1' may not share a security association with LMA2/LMA2', and MAG2/MAG2' may not share one with LMA1, respectively. 🙈
it's not required that the LMAs holding the registrations for the MN and CN be part of the same provider domain as the MAGs they attach to. 😭 when the MN's MAG and LMA belong to different provider domains (A and C), localized routing is subject to policy governing the service level agreements between those domains. the same goes for the provider domains providing the CN's MAG and LMA. 🫶 based on all of this, four PMIPv6 roaming and non-roaming cases can be taken into account:
- Case 1: The MN's MAG (
MAG1), the CN's MAG (MAG2), the MN's LMA (LMA1), and the CN's LMA (LMA2) are all located in the same provider domain A. 🍓 - Case 2: The MN's MAG (
MAG1), the CN's MAG (MAG2), and the MN's LMA (LMA1) are located in the same domain A, while the CN's LMA (LMA2') is located in provider domain B. 🌸 - Case 3: The MN's MAG (
MAG1') and the CN's MAG (MAG2') are located in domain C, while the MN's LMA (LMA1) and the CN's LMA (LMA2) are located in provider domain A. 🧚 - Case 4: The MN's MAG (
MAG1') and the CN's MAG (MAG2') are located in provider domain C, while the MN's LMA (LMA1) is located in provider domain A and the CN's LMA (LMA2') is located in provider domain B. 💀
in these roaming cases, the MN can be allowed to roam within its own domain (e.g., the MN's home domain, where its LMA lives) or across different domains (e.g., the MN moves from its home domain to a visited domain). ✨ during mobility, the CN and MN should remain attached to MAGs in the same provider domain so that traffic between their MAGs keeps routing efficiently. 👑
|
+-----+ +-----+ | +-----+
|LMA1 | |LMA2 | | |LMA2'|
+-----+ +-----+ | +-----+
|
|
|
|
+-----+ +-----+ |
|MAG1 | |MAG2 | |
+-----+ +-----+ |
|
|
Provider Domain A | Provider Domain B
------------------------------+-------------------------------
Provider Domain C
+-----+ +-----+
|MAG1'| |MAG2'|
+-----+ +-----+Figure 2: PMIPv6 Roaming Cases Considered for Localized Routing 🗺️
6. Security Considerations 🔐
this section is seriously important, bestie, so pay attention 🚨 a protocol solution for localized routing in a PMIPv6 network must counter unauthorized changes to a routing path. 😱 specifically, the control plane for localized routing must preclude any blocking or hijacking of mobile nodes' traffic by malicious or compromised network components. a security solution must also support suitable mechanisms for authenticating the control plane components of the localized routing functional architecture, for both roaming and non-roaming scenarios. and any possibility for Internet hosts to interfere with the localized routing procedure in a malicious way must be precluded. 💖
since network entities other than MNs and CNs do the signaling to set up localized routing, the MIPv6 return routability test [RFC3775] is not suitable for authenticating the associated signaling messages in PMIPv6. ⚠️ solutions for localized routing in PMIPv6 need to mitigate, or provide sufficient defense against, possible security threats. when PMIPv6 participants are administered within the same domain, infrastructure-based authorization mechanisms, such as IPsec, may be usable to protect the localized routing signaling. 🔒
existing security associations according to [RFC5213] can be reused to protect localized routing signaling on the interface between a MAG and an LMA. 🫶 in the case where a protocol solution for localized routing in PMIPv6 relies on protocol operation between MAGs, there must be a way to protect the signaling between those MAGs. the same applies to signaling on a possible protocol interface between two LMAs of the same domain. 🌈
7. Acknowledgments 🎀
many aspects of the problem space for route optimization in PMIPv6 were discussed in a PMIPv6 Route Optimization Design Goals document, which was submitted to the NetLMM WG in November 2007. 🥰 this group of contributors includes Sangjin Jeong, Christian Vogt, Ryuji Wakikawa, Marco Liebsch, Behcet Sarikaya, Shinta Sugimoto, Long Le, Alice Qinxia, and Jaehwoon Lee. huge thanks to Rajeev Koodli for his comments on the structure and scope of this problem statement for the NetExt WG. 🫶
this problem statement reflects the results of the discussion in the NetExt group. 👑 many thanks to Hidetoshi Yokota, Carlos Bernardos, Ashutosh Dutta, Sri Gundavelli, Mohana Jeyatharan, Jouni Korhonen, Glen Zorn, Dirk von Hugo, Frank Xia, Xiangsong Cui, and Basavaraj Patil for their comments and support in improving the quality of the problem statement. ✨
8. References 📚
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5213] Gundavelli, S., Ed., Leung, K., Devarapalli, V.,
Chowdhury, K., and B. Patil, "Proxy Mobile IPv6",
RFC 5213, August 2008.
[RFC5844] Wakikawa, R. and S. Gundavelli, "IPv4 Support for Proxy
Mobile IPv6", RFC 5844, May 2010.8.2. Informative References
[PMIP6-LR] Zorn, G., Wu, Q., Liebsch, M., and J. Korhonen, "Diameter
Support for Proxy Mobile IPv6 Localized Routing", Work
in Progress, May 2011.
[RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support
in IPv6", RFC 3775, June 2004.
[RFC5779] Korhonen, J., Ed., Bournelle, J., Chowdhury, K., Muhanna,
A., and U. Meyer, "Diameter Proxy Mobile IPv6: Mobile
Access Gateway and Local Mobility Anchor Interaction with
Diameter Server", RFC 5779, February 2010.Authors' Addresses 🦋
Marco Liebsch (editor)
NEC Laboratories Europe
NEC Europe Ltd.
Kurfuersten-Anlage 36
69115 Heidelberg
Germany
Phone: +49 6221 4342146
EMail: liebsch@neclab.eu
Sangjin Jeong
ETRI
218 Gajeongno, Yuseong
Daejeon 305-700
Korea
Phone: +82 42 860 1877
EMail: sjjeong@etri.re.kr
Qin Wu
Huawei Technologies Co., Ltd
101 Software Avenue, Yuhua District
Nanjing 210012
China
Phone: +86 25 56623633
EMail: sunseawq@huawei.com📦 where this page comes from
- ietf: rfc6279 2011-06
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