MEXT Working Group M. Liebsch Internet-Draft NEC Intended status: Standards Track October 25, 2011 Expires: April 27, 2012 Per-Host Locators for Distributed Mobility Management draft-liebsch-mext-dmm-nat-phl-00.txt Abstract Mobile operators consider the distribution of mobility anchors to enable offloading some traffic from their core network. In scope of a solution for Distributed Mobility Management is the maintenance of IP sessions and IP address continuity when mobile nodes get a new mobility anchor assigned during handover. This document proposes the use of identifier-locator split concepts to achieve optimal routing of data packets to a mobile node's current mobility anchor. The use of per-host locator IP addresses allows translation of addresses within the mobile operator network to route packets to the mobile node's current mobility anchor, while address translation is kept transparent to the communication endpoints. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on April 27, 2012. 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 (http://trustee.ietf.org/license-info) in effect on the date of Liebsch Expires April 27, 2012 [Page 1] Internet-Draft DMM per-host locator October 2011 publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions and Terminology . . . . . . . . . . . . . . . . . 4 3. Routing Plane Considerations of DMM . . . . . . . . . . . . . 5 4. Use of NATs and per-host locators . . . . . . . . . . . . . . 8 5. Security Considerations . . . . . . . . . . . . . . . . . . . 10 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 7. Normative References . . . . . . . . . . . . . . . . . . . . . 12 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 13 Liebsch Expires April 27, 2012 [Page 2] Internet-Draft DMM per-host locator October 2011 1. Introduction The concept of Distributed Mobility Management (DMM) in based on the distribution of mobility anchors towards the access networks to provide mobile nodes with local anchors and enable optimal routing of traffic above anchor level to any kind of serving point, e.g. distributed content caches. The closer mobility anchors are located to mobile nodes, the more a mobile node's handover may necessitate the assignment of a new mobility anchor. Continuity of a mobile node's IP address or IP address prefix enables IP session continuity, but creates the problem of routing downlink packets to the mobile node's current mobility anchor. Different solutions and associated extensions to IP mobility management protocols are being considered to maintain a mobile node's IP session after mobility anchor relocation. The solution for DMM as described in this document adopts the concept of an identifier-locator split to solve the routing above anchor level and enable optimal routes to the mobile node's current mobility anchor. Whereas the mobile node's Home Network Prefix (HNP) or Home Address is treated solely as identifier after mobility anchor relocation, the mobile node's current mobility anchor represents the locator. The proposed solution assumes an Ingress Router (IR) which resolves the MN's identifier into a locator address. The mobile node's current mobility anchor serves as Egress Router (ER). Instead of using encapsulation to tunnel packets between an IR and the ER, per-host locator addresses are used to address translate downlink packets at the IR(s) and route packets to the mobile node's anchor. Locator addresses are overloaded to carry identifier information, which allows the ER to reverse address translate the packet's destination address into the mobile node's identifier (HNP or Home Address) as assigned by the initial mobility anchor. Liebsch Expires April 27, 2012 [Page 3] Internet-Draft DMM per-host locator October 2011 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]. Liebsch Expires April 27, 2012 [Page 4] Internet-Draft DMM per-host locator October 2011 3. Routing Plane Considerations of DMM The problem of routing downlink packets to the mobile node's current mobility anchor after anchor relocation is depicted in Figure 1. The MN initially attaches to a Mobility Anchor (MA) and gets assigned an HNP from this MA's prefix pool in case Proxy Mobile IPv6 is used as mobility management protocol below MAs. In case Mobile IPv6 is used, the initial MA assigns a Home Address to the MN. In the following description, PMIPv6 is assumed, whereas the proposed solution for DMM is independent of the mobility management protocol. The MN's initial anchor is denoted as previous MA (pMA), whereas the new anchor is denoted as new MA (nMA) The following symbolic notation of IP addresses is used: [Prefix]:: [Suffix]. +--+ |CN| +--+ : :data, dest. address A:1::1 : V ?? Mobile Operator Routing Plane PFX A:x:: PFX B:x:: +----+ +----+ |pMA | |nMA | +----+ +----+ |pAR/| |nAR/| |pMAG| |nMAG| +----+ +----+ . / . +--+ / . |MN|/ +--+ A:1::1 Figure 1: Issue of routing downlink packets after mobility anchor relocation The initial anchor pMA assigns the prefix A:1:: to the MN as a result of the MN's registration. Routers in the mobile operator's core network forward all packets with prefix (PFX) A:x:: towards pMA. As a result of handover, the MN gets a new mobility anchor (nMA) assigned. In case nMA continues anchoring the MN's initially Liebsch Expires April 27, 2012 [Page 5] Internet-Draft DMM per-host locator October 2011 assigned IP address prefix, the DMM solution must enable forwarding of downlink packets to the nMA instead of following the default routing states, which forward all A:x:: prefixes to the pMA. Forwarding of packets from the pMA to the nMA may imply suboptimal routes from the CN. Figure 2 depicts the generic concept of using an Ingress Router (IR) to resolve the MN's HNP into the associated locator address, which is represented by the MN's current MA (nMA). The mechanism to resolve the locator is out of scope of this version of the document. As the nMA serves as locator and ER, the IR can set up a forwarding tunnel to the ER. The inner packet carries the MN's identifier, which allows forwarding of the packet after decapsulation of the tunnel at the ER according to the mobility management protocol supported by the nMA. +--+ |CN| +--+ : :data, dest. address A:1::1 : V +--+ |IR| +--+ A:1::1 is identifier, B:254::254 is locator || ==================|| host route between IR and ER || || VV +----+ +------+ A:254::254|pMA | |nMA/ER| B:254::254 +----+ ++----++ |pAR/| |nAR/| |pMAG| |nMAG| +----+ +----+ . / . +--+ / . |MN|/ +--+ A:1::1 Figure 2: Identifier-Locator split to solve DMM on the routing plane to enable IP address continuity after anchor relocation Liebsch Expires April 27, 2012 [Page 6] Internet-Draft DMM per-host locator October 2011 Since the IR can be topologically far away from the nMA, the solution described in this document is based on address translation instead of using encapsulation between the IR and the ER. Liebsch Expires April 27, 2012 [Page 7] Internet-Draft DMM per-host locator October 2011 4. Use of NATs and per-host locators Translation of the MN's IP address into the locator address (pMA) implies loosing identifier information, which results in an issue at the ER to reverse address translate the MN's downlink packets into the associated identifier address (HNP, Home Address). Hence, the proposed solution is based on per-host locators instead of referring to the nMA's IP address as locator. Building the per-host locator is intrinsically supported by MAs for IP mobility management and are represented by the HNP or the Home Address respectively. At the nMA, the initially assigned address serves as identifier (HNP_id), whereas the nMA assigns a new HNP to the MN after registration, which is treated as per-host locator (HNP_loc). The HNP_loc is not advertised to the MN for address configuration, but provided to a mapping system, which enables IRs to resolve the HNP_id into an HNP_loc. The description of the mapping system is out of scope of the current version of this document. Figure 3 illustrates NATing the downlink packet's destination address at the IR into the HNP_loc. According to local binding information, the nMA can reverse address translate the packet into the original IP address of the MN, which carries the HNP_id prefix. Further forwarding from the nMA is performed according to the used mobility management protocol. Liebsch Expires April 27, 2012 [Page 8] Internet-Draft DMM per-host locator October 2011 +--+ |CN| +--+ : :data, dest. address A:1::1 : V +--+---+ |IR|NAT|--------------+ +--+---+ |data, dest. address B:1::1 | | | V +----+ MN's BCE@pMA: |NAT | MN's BCE@nMA: HNP A:1:: +----+ ++----++ HNP_id A:1:: |pMA | |nMA/ER| HNP_loc B:1:: +----+ ++----++ |pAR/| |nAR/| |pMAG| |nMAG| +----+ /+----+ . / . +--+ / . |MN|/ +--+ A:1::1 Figure 3: Using per-host locators to enable reverse NAT on the MN's current mobility anchor (nMA) Liebsch Expires April 27, 2012 [Page 9] Internet-Draft DMM per-host locator October 2011 5. Security Considerations Secure inter-working between with the mapping system must be established to avoid entering addresses of a malicious node as HNP_loc. Liebsch Expires April 27, 2012 [Page 10] Internet-Draft DMM per-host locator October 2011 6. IANA Considerations So far no need for IANA actions has been identified. Liebsch Expires April 27, 2012 [Page 11] Internet-Draft DMM per-host locator October 2011 7. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. Liebsch Expires April 27, 2012 [Page 12] Internet-Draft DMM per-host locator October 2011 Author's Address Marco Liebsch NEC Laboratories Europe NEC Europe Ltd. Kurfuersten-Anlage 36 D-69115 Heidelberg, Germany Phone: +49 6221 4342146 Email: liebsch@neclab.eu Liebsch Expires April 27, 2012 [Page 13]