NEMO Working Group J. Charbon Internet-Draft Keio university, Louis Pasteur Expires: December 30, 2003 university and WIDE C-W. Ng Panasonic Singapore Labs K. Mitsuya T. Ernst Keio university and WIDE July 1, 2003 Evaluating Multi-homing Support in NEMO Basic Solution draft-charbon-nemo-multihoming-evaluation-00 Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. 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." The list of current Internet-Drafts can be accessed at http:// www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on December 30, 2003. Copyright Notice Copyright (C) The Internet Society (2003). All Rights Reserved. Abstract This draft describes and explains prerequisites for NEMO Basic to support Multi-homing. We study those prerequisites with respect to each case of a taxonomy proposed to the NEMO WG and we analyze how the NEMO basic support solution fits with them. The analysis of each case listed in this taxonomy is broken into three parts, prerequisites, comments, and solution behaviors. Charbon, et al. Expires December 30, 2003 [Page 1] Internet-Draft Multi-homing in NEMO Basic Solution July 2003 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.1 Context and Motivations . . . . . . . . . . . . . . . . . . . 4 1.2 Terms and Abbreviations . . . . . . . . . . . . . . . . . . . 4 1.3 Multi-Homing & Support levels . . . . . . . . . . . . . . . . 4 1.4 Organization . . . . . . . . . . . . . . . . . . . . . . . . . 5 2. Case (0,0,0) . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.1 Prerequisites . . . . . . . . . . . . . . . . . . . . . . . . 7 2.2 Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.3 Solution behaviors . . . . . . . . . . . . . . . . . . . . . . 10 3. Case (1,0,0) . . . . . . . . . . . . . . . . . . . . . . . . . 12 3.1 Prerequisites . . . . . . . . . . . . . . . . . . . . . . . . 12 3.2 Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 3.3 Solution behaviors . . . . . . . . . . . . . . . . . . . . . . 13 4. Case (0,1,0) . . . . . . . . . . . . . . . . . . . . . . . . . 14 4.1 Prerequisites . . . . . . . . . . . . . . . . . . . . . . . . 14 4.2 Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 4.3 Solution behaviors . . . . . . . . . . . . . . . . . . . . . . 16 5. Case (1,1,0) . . . . . . . . . . . . . . . . . . . . . . . . . 17 5.1 Prerequisites . . . . . . . . . . . . . . . . . . . . . . . . 17 5.2 Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 5.3 Solution behaviors . . . . . . . . . . . . . . . . . . . . . . 17 6. Case (0,0,1) . . . . . . . . . . . . . . . . . . . . . . . . . 18 6.1 Prerequisites . . . . . . . . . . . . . . . . . . . . . . . . 18 6.2 Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 6.3 Solution behaviors . . . . . . . . . . . . . . . . . . . . . . 18 7. Case (1,0,1) . . . . . . . . . . . . . . . . . . . . . . . . . 19 7.1 Solution requirements . . . . . . . . . . . . . . . . . . . . 19 7.2 Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 7.3 Solution behaviors . . . . . . . . . . . . . . . . . . . . . . 20 8. Case (0,1,1) . . . . . . . . . . . . . . . . . . . . . . . . . 21 8.1 Solution requirements . . . . . . . . . . . . . . . . . . . . 21 8.2 Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 8.3 Solution behaviors . . . . . . . . . . . . . . . . . . . . . . 21 9. Case (1,1,1) . . . . . . . . . . . . . . . . . . . . . . . . . 22 9.1 Solution requirements . . . . . . . . . . . . . . . . . . . . 22 9.2 Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 9.3 Solution behaviors . . . . . . . . . . . . . . . . . . . . . . 22 Charbon, et al. Expires December 30, 2003 [Page 2] Internet-Draft Multi-homing in NEMO Basic Solution July 2003 10. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . 23 11. Security Considerations . . . . . . . . . . . . . . . . . . . 24 12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 25 References . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 27 Intellectual Property and Copyright Statements . . . . . . . . 29 Charbon, et al. Expires December 30, 2003 [Page 3] Internet-Draft Multi-homing in NEMO Basic Solution July 2003 1. Introduction 1.1 Context and Motivations As specified in the NEMO Basic Support in Requirement R.12 [Section 5. NEMO Basic Support One-liner Requirements] [2], the NEMO WG must ensure that the basic solution produced does not prevent the use of Multi-homing. However the NEMO Basic support solution [1] does not specify any particular mechanism to manage Multi-homing, but discussion on this purpose is still open (see [Section 7. Extended Home Network] [1]). This draft complements [4], analyzes the behavior of NEMO Basic Support [1] and deployment issues in different Multi-homing scenarios. This analysis can provide a preliminary evaluation of the NEMO basic support solution with respect to Multi-homing support for further discussions. It is assumed that the readers are familiar with the NEMO terminology specified in [3] and the taxonomy described in [4]. 1.2 Terms and Abbreviations In addition to the terms defined in [3], we use the following abbreviations in this memo: Prefix-BU: Mobile Network Prefix Binding Update 1.3 Multi-Homing & Support levels In order to evaluate the NEMO basic solution, the Multi-homing support can be classified into three main categories: o Fault-Tolerance/Redundancy: As long as the Mobile Network maintains at least one connection to the Internet, connectivity for all Mobile Nodes is guaranteed. This behavior is separated into two sub-classes: - Without transparency: The lost of one connection to the Internet breaks transport sessions that use it; however, new transport sessions are possible. - With transparency: The lost of one connection to the Internet is transparent for Layer 4 and above, i.e. lost of one connection does not disrupt transport sessions. Charbon, et al. Expires December 30, 2003 [Page 4] Internet-Draft Multi-homing in NEMO Basic Solution July 2003 o Load-Sharing: This is achieved when the traffic load is distributed among different connections between the mobile network and the Internet. Here, we do not indulge into the more exotic forms of load balancing such as random selection, round-robin per-packet, per-connection etc. As long as the protocol uses all active connections simultaneously, Load-sharing will have been deemed achieved. The benefits of load sharing is studied for inbound and outbound traffic. o Policy: The management of traffic can be done by any possible mechanism. For example, it may depend on: * The kind/cost of connection. * Social policy based on schedule. * The class of the avian carriers [8]. In fact, we only consider whether the solution provides a mechanism to carry some policy informations - such as the Flow Label in IPv6 header (see [Section 6. Flow Labels] [7]) - because going deeper into analyzing the solutions for all policy cases is too complex. 1.4 Organization In the remaining sections of this draft, we will analyze the behavior of NEMO basic support in each scenario from the Multi-homing taxonomy [4]. The analysis of each is broken into three parts: 1. Prerequisites: Prerequisites for Multi-homing support and its benefits against each classes defined above. 2. Comments: About prerequisites and deployment issues and other things related. 3. Solution Behaviors: How the NEMO Basic current solution support theses prerequisites. The "Prerequisites" part is syntactical in nature, the "Comments" part detailed, and the "Solution Behaviors" one technical. Charbon, et al. Expires December 30, 2003 [Page 5] The first case is a long description since we have to explain the prerequisites in detail. Thereafter, in subsequent sections we will aggregate the prerequisites as much as possible. Charbon, et al. Expires December 30, 2003 [Page 6] Internet-Draft Multi-homing in NEMO Basic Solution July 2003 2. Case (0,0,0) Illustration of the case: _____ _ p _ | | |_|-|<-_ |-|_|-| |-| _ _ |-|_|=| |_____| | _ |-|_| |_|-| | |-|_|-| | MNNs MR AR Internet AR HA 2.1 Prerequisites o Redundancy: If an interface/link is broken, use the other: No additional prerequisites at NEMO level. But for efficient support of this benefit the layer 2 have to send interface/link informations or orders to NEMO. And this redundancy is always transparent: Read "Fault-Tolerance and the MNNs" in (Section 2.2). But this behavior is not sufficient to respect the requirements: Read "Load-sharing & Requirements" in (Section 2.2). o Load-Sharing: For this class the solution MUST at least: 1. Allows the use of several active bi-directional tunnels simultaneously between MR and HA. 2. Allows the binding of multiple CoAs against the same MNP. 3. Provides a method to identify which CoA a Prefix-BU is meant to update. Read "CoA Identification" in (Section 2.2). In this case the MR and the HA MUST use the two bi-directional tunnels simultaneously. Read "Load-sharing & Requirements" in (Section 2.2). * Outbound Traffic: The MR distributes between its CoAs. There is no assumption on the distribution mechanism. Charbon, et al. Expires December 30, 2003 [Page 7] Internet-Draft Multi-homing in NEMO Basic Solution July 2003 * Inbound Traffic: The HA distributes between MR's CoAs. The distribution can be statically fixed or be more dynamic: A preference can be sent with each Prefix-BU to mark the preference of each CoA in the HA's Binding Cache. o Policy: * Outbound Traffic: This behavior depends on the NEMO implementation. No way to impose an algorithm. * Inbound Traffic: Provide a policy field or policy sub-option with each Prefix-BU to indicate a policy management for each CoA to the HA. 2.2 Comments o CoA Identification: To illustrate this prerequisite, we consider the following example: The MR has two CoAs: CoA-1 and CoA-2. The HA have in its "NEMO Binding Cache" - Here this is a logical view of this cache : +=========================+=================+ | MNP/Prefix Length | Care Of Address | +=========================+=================+ | MNP-1/Length-1 | CoA-1 | +-------------------------+-----------------+ | MNP-1/Length-1 | CoA-2 | +=========================+=================+ Then the HA receives a Prefix-BU which contains: +=========================+=================+ | MNP/Prefix Length | Care Of Address | +=========================+=================+ | MNP-1/Length-1 | CoA-New | +=========================+=================+ The question is: Which CoA should CoA-New updates? CoA-1 or CoA-2? The solution needs a way to differentiate each CoA Charbon, et al. Expires December 30, 2003 [Page 8] Internet-Draft Multi-homing in NEMO Basic Solution July 2003 binding. o Load-sharing & Requirements: Fault-Tolerance is not sufficient, in all configuration cases, to conform to the Multi-Homing requirements defined in NEMO: Referring to [Section 5. Multi-homing] [3] the definition of a Multi-homed Mobile Router is: A MR is multi-homed when it has simultaneously more than one active connection to the Internet, [...] And according to [Section 5. NEMO Basic Support One-liner Requirements] [2]: R12: The solution MUST function for multi-homed MR and multi-homed mobile networks as defined in [NEMO-TERMS]). Particularly: R12.1: The solution MUST function for multi-MR mobile networks Thus the NEMO solution MUST manage network traffic simultaneously through the several connection of a same MR. o MR is the only one: Here only the MR is Multi-Homed and thus depending on the desired level of Multi-Homing, there exists several solutions to deal with this case, such as [5] and [6] deal with Multi-Interface issue and Mobility. o Fault-Tolerance and the MNNs: This configuration does not change anything on the behavior of MNNs: the MNNs always send their packets to the same interface - i.e. the ingress interface of MR. Thus the Fault-Tolerance with Transparency benefit is naturally provided to the MNNs. o Load-Sharing mechanisms: The MR can use many algorithms to share the outbound traffic according to administrator wishes. Same remark for each (0,*,*) case. For the inbound one, a preference can be sent with each Prefix-BU to mark preference of each CoA in the HA's binding table, and thus Charbon, et al. Expires December 30, 2003 [Page 9] Internet-Draft Multi-homing in NEMO Basic Solution July 2003 HA can perform load sharing according to MR's preference. Same remark for each (*,0,*) cases. 2.3 Solution behaviors o Against Load-Sharing: 1. Doesn't specify the simultaneous use of several bi-directional tunnels but doesn't prevent it. 2. Doesn't specify the binding of multiple CoAs against the same MNP but doesn't prevent it. 3. Doesn't provides a method to identify each CoA but doesn't prevent it: Here an explanation of one of possibility of this management: As long as there is no specific field for a CoA ID, the solution have to use a field present in current Prefix-BU definition. The only common field is each type of Prefix-BU - Implicit, Explicit and Explicit combined - is the Home Address Option in the Destination Option Header [Section 6.3 Home Address Option] [13]. Thus a NEMO implementation can create a Home Address for each egress interface. And when a CoA on an egress interface change, use in Prefix-BU the corresponding Home Address in the Home Address Option. An example to make clear this behavior: HA Routing Table & Binding Cache before: +===============+=================+=========================+ | Home Address | Care-of Address | MN Prefix/Prefix Length | +===============+=================+=========================+ | HoA-1 | CoA-1 | MNP-1/Length-1 | | HoA-2 | CoA-2 | MNP-1/Length-1 | +===============+=================+=========================+ Here HoA-x is the Home Address corresponding to the egress interface x on which is assigned CoA-x. Now the HA receives a Prefix-BU because CoA-1 has changed to CoA-New. Charbon, et al. Expires December 30, 2003 [Page 10] Internet-Draft Multi-homing in NEMO Basic Solution July 2003 The Prefix-BU: +===============+=================+=========================+ | Home Address | Care-of Address | MN Prefix/Prefix Length | +===============+=================+=========================+ | HoA-1 | CoA-New | MNP-1/Length-1 | +===============+=================+=========================+ The HA updates the HoA-1 entry, and thus the CoA-1 binding. Routing Table & Binding Cache after: +===============+=================+=========================+ | Home Address | Care-of Address | MN Prefix/Prefix Length | +===============+=================+=========================+ | HoA-1 | CoA-New | MNP-1/Length-1 | | HoA-2 | CoA-2 | MNP-1/Length-1 | +===============+=================+=========================+ You can see the difference with "CoA Identification" (Section 2.2). And an example of creation of Home Address according to egress interface can be: Egress Interface 1 -> EUI-64-1 -> Home Address for this interface: MNP:EUI-64-1 Egress Interface 2 -> EUI-64-2 -> Home Address for this interface: MNP:EUI-64-2 Maybe the solution should specify this behavior because it is very specific to NEMO. o Against dynamic Load-sharing and Policy: The solution didn't specify anything about a kind of preference/ policy field, but maybe an NEMO implementation can use some part of the reserved field in the MNP Option [Section 4.3. Mobile Network Prefix Option] [1] or in a sub-option. Charbon, et al. Expires December 30, 2003 [Page 11] Internet-Draft Multi-homing in NEMO Basic Solution July 2003 3. Case (1,0,0) Illustration of the case: MR2 p <-_ | _ |-|_|-| _____ |_|-| |-| | _ | | |-| _ |_|-| _ |-|_____| | _ |-|_| |-|_|-| |-|_|-| <- | | p MNNs MR1 Internet AR HA 3.1 Prerequisites For this case the solution MUST at least support all prerequisites from (Section 2.1). Differences with (0,0,0) case: o Load-sharing: For outbound traffic the MNNs distribute outgoing packets between the MRs. This kind of sharing is out of scope of NEMO WG. Read "Load-Sharing for Outbound Traffic" in (Section 3.2). 3.2 Comments o Fault-Tolerance is already done: Here all MNNs operate a selection of default router [Section 6.3.6. Default Router Selection] [9] which provide Fault-Tolerance benefit. Note: Depending on the implementation and the type of traffic this mechanism can be acceptable or too slow [Section 7.3. Neighbor Unreachability Detection] [9]. Charbon, et al. Expires December 30, 2003 [Page 12] Internet-Draft Multi-homing in NEMO Basic Solution July 2003 o Load-Sharing for Outbound Traffic: In this case, how to provide this benefit is not in the scope of NEMO Working Group. Anyway a good idea can be: [Default Router Preferences, More-Specific Routes, and Load Sharing] [10]. This solution can be considered for each (1,*,*) cases. 3.3 Solution behaviors Same behaviors as in (Section 2.3). Charbon, et al. Expires December 30, 2003 [Page 13] Internet-Draft Multi-homing in NEMO Basic Solution July 2003 4. Case (0,1,0) Illustration of the case: AR HA2 [Manage CoAx] _ | |-|_|-| _ _____ | |-|_| _ p _ | |-| |_|-|<-_ x|-|_|-| | _ |-|_|=| |_____|-| _ |_|-| y| | _ |-|_| |-|_|-| | MNNs MR AR Internet AR HA1 [Manage CoAy] 4.1 Prerequisites o Redundancy: Same as "Reduncancy" in (Section 2.1). o Load-Sharing: In this case the MR and the HAs MUST use the two bi-directional tunnels simultaneously. Read "Load-sharing & Requirements" in (Section 2.2). * Outbound Traffic: The MR distribute between its CoAs. There is no assumption on the distribution mechanism. * Inbound Traffic: The CNs distribute between the two HAs. No prerequisites at NEMO level for static Load-sharing and for dynamic one read "Interaction with routing protocols" in (Section 4.2). o Policy: * Outbound Traffic: This behavior is dependent on the NEMO implementation. No way to impose an algorithm. Charbon, et al. Expires December 30, 2003 [Page 14] Internet-Draft Multi-homing in NEMO Basic Solution July 2003 * Inbound Traffic: Close to Load-sharing prerequisite. Thus read "Interaction with routing protocols" in (Section 4.2). 4.2 Comments o Interaction with routing protocols: The main goal of this case is to provide HA redundancy and a kind of Routing Optimization. And here both HAs announce the same MNP. So: * The two HAs are in the same IGP domain: Each HA advertise the same MNP via the IGP routing protocol. The metric/cost used for these advertisements can be statically configured on the HA or dynamically by MR which sending a kind of "priority" - to make the difference with the "preference" field cited above - information to each HAs. For example this information can inside the Prefix-BU as sub-option. This idea come from Ryuji Wakikawa. * Is possible that theses HAs can be in different AS? Yes, read [Section 5.1.2. Possibly Multihomed, An Identical Prefix from a Different Origin] [11]. Advantage: + The inbound traffic always going to the cheapest HA according to the BGP policy of the CN domain. Inconvenient: + This route should be published in the Internet Route Registry for the two AS. Elsewhere, these announcement can be deleted by mechanism which are used to fight "route hijacking" in BGP. + The route optimization effect is only available for the inbound traffic. + The BGP protocol announce only one route, thus the CN has no "real" choice. The choice is made by the border router of the CN's AS. Charbon, et al. Expires December 30, 2003 [Page 15] Internet-Draft Multi-homing in NEMO Basic Solution July 2003 o Routing Optimization: If the goal is to provide a pure Routing Optimization - for inbound and outbound traffic - the solution has to establish a kind of Inter-HA protocol. But it's too early to say if this behavior have to be supported by NEMO Basic Support. In conclusion, there is no strong prerequisite at NEMO level, but some at deployment one. 4.3 Solution behaviors o Against Redundancy: The proposed solution should work without any changes. o Against Load-sharing and Policy: The solution doesn't provide any "priority" carriage to the HAs to influence the routing announces thus dynamic Load-sharing for inbound traffic is not provided. Charbon, et al. Expires December 30, 2003 [Page 16] Internet-Draft Multi-homing in NEMO Basic Solution July 2003 5. Case (1,1,0) Illustration of the case: MR2 AR HA2 [Manage MR2] p _ | <-_ | |-|_|-| _ _ |-|_|-| _____ | |-|_| |_|-| |-| |-| _ | | | |_|-| _ |-|_____|-| _ |-|_|-| | _ |-|_| <- | |-|_|-| p | MNNs MR1 Internet AR HA1 [Manage MR1] 5.1 Prerequisites For this case the solution just have to: o Refer to "Comments" in (Section 4.2) and in "Fault-Tolerance is already done" at (Section 3.2). 5.2 Comments Load-Sharing distribution: For Outbound Traffic: The MNNs distribute traffic between the two MRs. For Inbound Traffic: The CNs distribute traffic between the two HAs. 5.3 Solution behaviors Same behaviors as in (Section 4.3). Charbon, et al. Expires December 30, 2003 [Page 17] Internet-Draft Multi-homing in NEMO Basic Solution July 2003 6. Case (0,0,1) Illustration of the case: _____ _ p1,p2 _ | | |_|-|<-_ |-|_|-| |-| _ _ |-|_|=| |_____| | _ |-|_| |_|-| | |-|_|-| | MNNs MR AR Internet AR HA 6.1 Prerequisites For this case the solution MUST at least support all prerequisites from (Section 2.1). 6.2 Comments o Source Address selection: Each MNN gets two global addresses and thus performs Source Address Selection [12]. o Load-Sharing distribution: For Outbound Traffic: The MR distributes traffic between its two CoAs. For Inbound Traffic: The HA distributes traffic between the two MR's CoAs. 6.3 Solution behaviors Same behaviors as in (Section 2.3). Charbon, et al. Expires December 30, 2003 [Page 18] Internet-Draft Multi-homing in NEMO Basic Solution July 2003 7. Case (1,0,1) Illustration of the case: MR2 p2 <-_ | _ |-|_|-| _____ |_|-| |-| | _ | | |-| _ |_|-| _ |-|_____| | _ |-|_| |-|_|-| |-|_|-| <- | | p1 MNNs MR1 Internet AR HA 7.1 Solution requirements For this case, the solution MUST at least do nothing special because for the HA, the Mobile Network is seen like two distinct Mobile Network. 7.2 Comments o Source Address selection: Each MNN gets two global addresses and thus performs Source Address selection. However, the MRs or the HA can apply some kind of Ingress Filtering - like Reverse Path Filtering or other - and depending on the routing protocol configuration, a MR/the HA can refuse to forward packets with a different source prefix other than the MR advertised MNP. In [Section 7. Interactions with Routing] [12]: "Implementations may also use the choice of router to influence the choice of source address. For example, suppose a host is on a link with two routers. One router is advertising a global prefix A and the other router is advertising global prefix B. Then when sending via the first router, the host may prefer source addresses with prefix A and when sending via the second router, prefer source addresses with prefix B." Thus care must be taken when configuring MRs and routing protocol Charbon, et al. Expires December 30, 2003 [Page 19] Internet-Draft Multi-homing in NEMO Basic Solution July 2003 behavior between MRs and HA. o Redundancy without transparency: Suppose MR1 or the tunnel between MR1 and HA goes down, the MNNs that choose the p1 prefixed source address will lose their connections because they - if ingress filtering - can't send theses packets to MR2. But new connections are still possible by using the other source address corresponding to the prefix advertised by MR2 (i.e. p2). But the time to switch source address can be very long: the non-usable source address will have to become deprecated [5. Source Address Selection] [12]. Providing this kind of transparency is out of scope of NEMO Basic. For MNNs that act as a Mobile Host this issue should be solved in the Mobile-IP Working Group. o Load-Sharing distribution: For Outbound Traffic: The MNNs distribute traffic between the two MRs. For Inbound Traffic: The HA distributes traffic between the CoAs of each MR. 7.3 Solution behaviors The default behavior is enough to support this case. Charbon, et al. Expires December 30, 2003 [Page 20] Internet-Draft Multi-homing in NEMO Basic Solution July 2003 8. Case (0,1,1) Illustration of the case: AR HA2 [Manage p2] _ | |-|_|-| _ _____ | |-|_| _ p1,p2 _ | |-| |_|-|<-_ |-|_|-| | _ |-|_|=| |_____|-| _ |_|-| | | _ |-|_| |-|_|-| | MNNs MR AR Internet AR HA1 [Manage p1] 8.1 Solution requirements Nothing special because each HA see the same Mobile Network but through its own Mobile Network Prefix. 8.2 Comments o Redundancy without transparency: If HA1 or the tunnel between HA1 and the MR goes down, the MNNs that choose p1 prefixed source address will lose theirs connections because MR can't forward these packets to the HAy - because of the Ingress Filtering made by ISP of HA2. But new connections are possible by switching to the source address with the other mobile network prefix (i.e. p2). Again, we have the penalty of switching source addresses. o Load-Sharing distribution: For Outbound Traffic: The MR distributes traffic between its two CoAs. For Inbound Traffic: The CNs distribute between the two HAs. 8.3 Solution behaviors The default behavior is enough to support this case. Charbon, et al. Expires December 30, 2003 [Page 21] Internet-Draft Multi-homing in NEMO Basic Solution July 2003 9. Case (1,1,1) Illustration of the case: MR2 AR HA2 [Manage MR2] p2 _ | <-_ | |-|_|-| _ _ |-|_|-| _____ | |-|_| |_|-| |-| |-| _ | | | |_|-| _ |-|_____|-| _ |-|_|-| | _ |-|_| <- | |-|_|-| p1 | MNNs MR1 Internet AR HA1 [Manage MR1] 9.1 Solution requirements Nothing special because each HA see the same Mobile Network but through its own MR. 9.2 Comments o Redundancy without transparency: If MR1 or HA1 or the tunnel between MR1 and HA1 goes down, the MNNs that choose p1 prefixed source address will lose their connections because they can't send theses packets to the MR2 - the Ingress Filtering made by ISP of HA2. But new connections are possible by using the source address corresponding to the MNP advertised by MR2 (i.e. p2). o Load-Sharing distribution: For Outbound Traffic: The MNNs distribute between the two MRs. For Inbound Traffic: The CNs distribute between the two HAs. 9.3 Solution behaviors The default behavior is enough to support this case. Charbon, et al. Expires December 30, 2003 [Page 22] Internet-Draft Multi-homing in NEMO Basic Solution July 2003 10. Conclusions In this draft, we explore the level of Multi-homing support available in the NEMO Basic proposed solution with respect to Multi-homing requirements, the main goal being: "Do not prevent Multi-homing configurations/benefits by the using of NEMO Basic Support." and this goal is mainly respected. However, based on our analysis, we propose some improvements. o Preference & Priority: Theses two informations permit to manage the sharing/the policy of the Inbound traffic to the Mobile Network through several CoAs and/or several HAs. Theses information could be added to the Prefix-BU, and the proposed solution specify a field/an sub-option to permit some implementation to provide this benefit; or specify in the next release of NEMO protocol. o Multiple CoAs for the same MNP: The proposed solution doesn't have to specify anything one this subject, just to support it. But a paragraph on this purpose can be helpful for implementation's developers. The problem of Multi-homing in Network Mobility covers many specifications and network domains, which makes the ideas about this subject interesting but difficult to fix. We hope that this document can trigger further discussions on the Multi-homing aspect of NEMO basic solution. Charbon, et al. Expires December 30, 2003 [Page 23] Internet-Draft Multi-homing in NEMO Basic Solution July 2003 11. Security Considerations This document is an on-going work to evaluate the degree of Multi-homing support in NEMO solutions. There should be a separate draft produced by the working group to analyze security threats for network in motion. As such, no special security considerations is listed here. However, since this memo also looks into the analysis of problems in a Multi-homed mobile network, we will add problems related to security threat here as and when they are encountered. We also encourage interested readers to contribute to this part. Charbon, et al. Expires December 30, 2003 [Page 24] Internet-Draft Multi-homing in NEMO Basic Solution July 2003 12. Acknowledgements The authors would like express their appreciation to Ryuji Wakikawa and Pascal Thubert for their significant comments on this document. The authors would also like to extend their gratitude to people who have given valuable comments on various Multi-homing issues on the mailing list. Charbon, et al. Expires December 30, 2003 [Page 25] Internet-Draft Multi-homing in NEMO Basic Solution July 2003 References [1] Devarapalli, V., Wakikawa, R., Pestrescu, A. and P. Thubert, "Nemo Basic Support Protocol", Internet Draft: draft-ietf-nemo-basic-support-00.txt, Work In Progress, June 2003. [2] Ernst, T., et al, "Network Mobility Support Goals and Requirements", Internet Draft: draft-ietf-nemo-requirements-01.txt, Work In Progress, May 2003. [3] Ernst, T. and H-Y. Lach, "Network Mobility Support Terminology", Internet Draft: draft-ietf-nemo-terminology-00.txt, Work In Progress, May 2003. [4] Ng, C-W. and J. Charbon, "Multi-Homing Issues in Bi-directional Tunneling", Internet Draft: draft-ng-nemo-multihoming-issues-01, Work In Progress, May 2003. [5] Wakikawa, R., Uehara, K. and T. Ernst, "Multiple Care-of-Address Registration on Mobile IPv6", Internet Draft: draft-wakikawa-mobileip-multiplecoa-01.txt, Work In Progress, June 2003. [6] Montavont, N. and T. Noel, "MIPv6 for Multiple Interfaces", Internet Draft: draft-montavont-mobileip-mmi-00.txt, Work Expired, Jully 2002. [7] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", RFC 2460, December 1998. [8] Waitzman, D., "IP over Avian Carriers with Quality of Service", RFC 2549, April 1999. [9] Narten, T., Nordmark, E. and W. Simpson, "Neighbor Discovery for IP Version 6 (IPv6)", RFC 2461, December 1998. [10] Draves, R. and R. Hinden, "Default Router Preferences, More-Specific Routes, and Load Sharing", Internet Draft: draft-ietf-ipv6-router-selection-02.txt, Work In Progress, June 2002. [11] Savola, P., "Examining Site Multi-homing in Finnish Networks", Master's Thesis. , April 2003. [12] Draves, R., "Default Address Selection for Internet Protocol Charbon, et al. Expires December 30, 2003 [Page 26] Internet-Draft Multi-homing in NEMO Basic Solution July 2003 version 6 (IPv6)", RFC 3484, February 2003. [13] David, D., Charles, C. and J. Jari, "Mobility Support in IPv6", Internet Draft: draft-ietf-mobileip-ipv6-23.txt, Work In Progress, May 2003. Authors' Addresses Julien Charbon Keio university, Murai Lab, Louis Pasteur university and WIDE project Keio University. 5322 Endo Fujisawa-shi, Kanagawa 252-8520 Japan Phone: +81-466-49-3529 Fax: +81-466-49-1101 EMail: julien@sfc.wide.ad.jp URI: http://www.sfc.wide.ad.jp/~julien/ Chan-Wah Ng Panasonic Singapore Laboratories Pte Ltd Blk 1022 Tai Seng Ave #06-3530 Tai Seng Industrial Estate Singapore 534415 SG Phone: +65 65505420 EMail: cwng@psl.com.sg Koshiro Mitsuya Keio university and WIDE project Keio University. 5322 Endo Fujisawa-shi, Kanagawa 252-8520 Japan Phone: +81-466-49-3529 Fax: +81-466-49-1101 EMail: mitsuya@sfc.wide.ad.jp URI: http://www.sfc.wide.ad.jp/~mitsuya/ Charbon, et al. Expires December 30, 2003 [Page 27] Internet-Draft Multi-homing in NEMO Basic Solution July 2003 Thierry Ernst Keio university and WIDE project Keio University. 5322 Endo Fujisawa-shi, Kanagawa 252-8520 Japan Phone: +81-466-49-1395 Fax: +81-466-49-1100 EMail: julien@sfc.wide.ad.jp URI: http://www.sfc.wide.ad.jp/~ernst/ Charbon, et al. Expires December 30, 2003 [Page 28] Internet-Draft Multi-homing in NEMO Basic Solution July 2003 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP-11. 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This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION Charbon, et al. Expires December 30, 2003 [Page 29] Internet-Draft Multi-homing in NEMO Basic Solution July 2003 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Acknowledgement Funding for the RFC Editor function is currently provided by the Internet Society. Charbon, et al. Expires December 30, 2003 [Page 30]