Network Working Group H. Yokota Internet-Draft KDDI Lab Intended status: Standards Track G. Dommety Expires: January 10, 2008 Cisco Systems, Inc. July 9, 2007 Mobile IPv6 Fast Handovers for 3G CDMA Networks draft-ietf-mipshop-3gfh-03.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. 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 January 10, 2008. Copyright Notice Copyright (C) The IETF Trust (2007). Yokota & Dommety Expires January 10, 2008 [Page 1] Internet-Draft 3G CDMA Fast Handover July 2007 Abstract Mobile IPv6 is designed to maintain its connectivity while moving from one network to another. It is adopted in 3G CDMA networks as a way to maintain connectivity when the mobile node moves between access routers. However, this handover procedure requires not only movement detection, but also the acquisition of a new care-of address and the sending of a binding update message to the home agent before the traffic begins to direct to the new location. During this period, packets destined for the mobile node will be lost, which may not be acceptable for real-time application such as Voice over IP (VoIP) or video telephony. This document specifies fast handover methods in the 3G context in order to reduce latency and packet loss during handover. Table of Contents 1. Requirements notation . . . . . . . . . . . . . . . . . . . . 3 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 4. Network reference model for Mobile IPv6 over 3G networks . . . 6 5. Fast handover procedures . . . . . . . . . . . . . . . . . . . 8 5.1. Predictive fast handover . . . . . . . . . . . . . . . . . 8 5.2. Reactive fast handover . . . . . . . . . . . . . . . . . . 13 5.3. Network-controlled fast handover . . . . . . . . . . . . . 16 6. Message Format . . . . . . . . . . . . . . . . . . . . . . . . 18 6.1. New Option for access-specific handover information . . . 18 7. Security Considerations . . . . . . . . . . . . . . . . . . . 19 8. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . 20 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21 9.1. Normative References . . . . . . . . . . . . . . . . . . . 21 9.2. Informative References . . . . . . . . . . . . . . . . . . 21 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 22 Intellectual Property and Copyright Statements . . . . . . . . . . 23 Yokota & Dommety Expires January 10, 2008 [Page 2] Internet-Draft 3G CDMA Fast Handover July 2007 1. Requirements notation 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 [1]. Yokota & Dommety Expires January 10, 2008 [Page 3] Internet-Draft 3G CDMA Fast Handover July 2007 2. Introduction Mobile IPv6 [2] allows mobile nodes (MNs) to maintain persistent IPv6 addresses while roaming around in IPv6 networks and it is adopted in 3G CDMA networks for handing off between different access provider networks [4]. During handover, however, the mobile node (MN) needs to switch the radio networks, to obtain a new Care-of Address (CoA) and to re-register with the home agent (HA), which causes a communication disruption. This is not desirable for real-time applications such as VoIP and video telephony. To reduce this disruption time or latency, a fast handover protocol for Mobile IPv6 [3] is proposed. In this proposal, there are two modes called "predictive" fast handover and "reactive" fast handover. This document first specifies how these fast handover modes can be applied in the 3G context and shows that several Mobile IPv6 bootstrapping procedures can be omitted. In the case where the lower layer can provide necessary information for handover, network-controlled fast handover defined in this document can also be applied. Yokota & Dommety Expires January 10, 2008 [Page 4] Internet-Draft 3G CDMA Fast Handover July 2007 3. Terminology This document refers to [4] for Mobile IPv6 fast handover terminology. Terms that first appear in this document are defined below: Forward Pilot Channel: A portion of the Forward Channel that carries the pilot. The Forward Channel is a portion of the physical layer channels transmitted from the access network to the MN. Sector: A typical cell divides its coverage area into several sectors. In 3G CDMA systems, each sector uses a different PN (Pseudo Noise) code offset. Home Link Prefix (HLP): The prefix address assigned to the home link where the MN should send the binding update message. This is one of the bootstrap parameters for the MN. Packet Data Serving Node (PDSN): An entity that routes MN originated or MN terminated packet data traffic. A PDSN establishes, maintains and terminates link- layer sessions to MNs [4]. A PDSN can be the access router in the visited access provider network. Yokota & Dommety Expires January 10, 2008 [Page 5] Internet-Draft 3G CDMA Fast Handover July 2007 4. Network reference model for Mobile IPv6 over 3G networks Figure 1 shows a simplified reference model of the Mobile IP enabled 3G networks. The home agent (HA) and AAA server (AAA) of the mobile node (MN) reside in the home IP network and the MN roams within or between the access provider network(s). Usually, the home IP network is not populated by the MNs, which are instead connected only to the access provider networks. Prior to the Mobile IPv6 registration, the MN establishes an access technology specific link-layer connection with the access router (AR). When the MN moves from one AR to another, the link-layer connection is re-established and a Mobile IPv6 handover is performed. Those ARs reside in either the same or different access provider network(s). The figure shows the situation, where the MN moves from the previous access router (PAR) to the new access router (NAR) via the radio access network (RAN). Home IP Network +........................+ . +--------+ +--------+ . . | HA |--| AAA | . . +--------+ +--------+ . +../......\..............+ / \ Access Provider Network(s) +.............+ +.............+ . +---------+ . . +---------+ . . | PAR | . . | NAR | . . +---------+ . . +---------+ . . |: . . :| . . |:L2link L2link:| . . |: . . :| . . +----+:---+ . . +---:+----+ . . | RAN | . . | RAN | . . +----+:---+ . . +---:+----+ . . |: . . :| . . +----+ . . +----+ . . | MN | ---------> | MN | . . +----+ . . +----+ . +.............+ +.............+ Figure 1: Reference Model for Mobile IP In 3G CDMA networks, pilot channels transmitted by base stations allow the MN to obtain a rapid and accurate C/I (carrier to interference) estimate. This estimate is based on measuring the strength of the Forward Pilot Channel or the pilot, which is associated with a sector of a base station (BS). The MN searches for the pilots and maintains those with sufficient signal strength in the Yokota & Dommety Expires January 10, 2008 [Page 6] Internet-Draft 3G CDMA Fast Handover July 2007 pilot sets. The MN sends measurement results, which include the offsets of the PN code in use and the C/Is in the pilot sets, to provide the access network (AN) with the estimate of sectors in its neighborhood. There are several triggers for the MN to send those estimates, e.g. when the strength of a pilot in the pilot sets is higher enough than that of the current pilot, the MN sends the estimates to the access network. If the serving access network finds that the sector associated with the highest pilot strength belongs to a different AR, it attempts to close the connection with the MN. The MN then attempts to get a new traffic channel assigned in the new access network, which is followed by establishing a new connection with the new AR. The MN can continually search for pilots without disrupting the data communication and a timely handover is assisted by the network. If the air interface information can be used as a trigger for the handover between access routers, fast and smooth handover of Mobile IPv6 can be realized in 3G CDMA networks. To assist the handover of the MN to the new AR, various types of information can be considered: the pilot sets, which include the candidates of the target sectors or BSs, the cell information where the MN resides, the serving nodes in the radio access network and the location of the MN if available. To identify the access network that the MN moves to or from, the Access Network Identifiers (ANID), which is composed of the System ID (SID), Network ID (NID) and Packet Zone ID (PZID) can be used [5]. In this document, a collection of such information is called "handover assist information". In 3G networks, the link-layer address of the new access point defined in [3] may not be available. If this is the case, the handover assist information SHOULD be used instead. Yokota & Dommety Expires January 10, 2008 [Page 7] Internet-Draft 3G CDMA Fast Handover July 2007 5. Fast handover procedures There are two modes defined in [3] according to the timing of sending FBU (Fast Binding Update); one is called "predictive mode," where the MN sends FBU and receives FBAck (Fast Binding Ack) on PAR (Previous Access Router)'s link and the other is called "reactive mode," where the MN sends FBU from NAR (New Access Router)'s link. In the predictive mode, the time and place the MN hands off must be indicated sufficiently before the time it actually happens. In cellular systems, since handovers are controlled by the network, the predictive mode is well applied. However, if the network is not configured to be able to identify the new AR, to which the MN is moving next, in a timely manner, the reactive mode is better applied. 5.1. Predictive fast handover Figure 2 shows the predictive mode of MIPv6 fast handover operation. When the MN finds a sector or a BS whose pilot signal is sufficiently strong, it initiates handover according to the following sequence: (a) A router solicitation for proxy router advertisement is sent to the PAR. (b) A proxy router advertisement containing the prefix in the NAR is sent back to the MN. (c) The MN creates an NCoA (new CoA) and sends the Fast Binding Update (FBU) storing the NCoA to the PAR, which in turn sends the Handover Initiate (HI) to the NAR. (d) The NAR sends the Handover Acknowledge (HAck) back to the PAR, which in turn sends the FBU acknowledgment (FBAck) to the MN. (e) The PAR starts forwarding packets toward the NCoA and the NAR captures and buffers them. (f) The link-layer connection associated with the PAR is closed and a new traffic channel is assigned in the new access network. (g) The MN attaches to the new access network. The attachment procedure is access technology specific. (h) The MN sends the Fast Neighbor Advertisement (FNA). (i) The NAR starts delivering packets to the MN. (j) The MN sends the BU to the HA to update the BCE with the NCoA and the HA sends back the BA to the MN. The AAA server may be Yokota & Dommety Expires January 10, 2008 [Page 8] Internet-Draft 3G CDMA Fast Handover July 2007 involved for authentication. MN PAR NAR HA AAA | RtSolPr | | | | (a) |------------->| | | | | PrRtAdv | | | | (b) |<-------------| | | | | FBU | Hl | | | (c) |------------->|-------------->| | | | FBack | HAck | | | (d) |<-------------|<--------------| | | | |forward packets| | | (e) | |==============>|(buffering) | | | | | | | (f) handover | | | | | | | | | +--------------------------------------------------------------+ (g) | Attachment procedure | +--------------------------------------------------------------+ | FNA | | | (h) |----------------------------->| | | | deliver packets | | | (i) |<=============================| | | | | BU/BA | (Authentication) (j) |<------------------------------------------->|<- - - - - - >| | | | | | Figure 2: MIPv6 Fast handover operation (predictive mode) It is assumed that the NAR can be identified by the PAR leveraging the handover assist information from the MN. To perform the predictive mode, the MN MUST send the FBU before the connection with the current access network is closed. If the MN fails to send the FBU before handover, it SHOULD fall back to the reactive mode. Even if the MN successfully sends the FBU, its reception by the PAR may be delayed for various reasons such as congestion. If the NAR receives the HI triggered by the delayed FBU after the reception of the FNA ((c) comes after (h)), then the NAR SHOULD send the HAck with handover not accepted and behave as the reactive mode. In (a), RtSolPr MUST include the MN and the New Access Point Link- Layer Address (LLA) options according to [3]. As for the MN-LLA option, the only available identifier is the interface ID, so it SHOULD be used for the MN-LLA. As for the New AP-LLA, the handover assist information may be applied. Since the LLA is assumed to be an IEEE identifier, even if the length field of the LLA option is in units of 8 octets, the actual length can be obtained by knowing that Yokota & Dommety Expires January 10, 2008 [Page 9] Internet-Draft 3G CDMA Fast Handover July 2007 the length of an IEEE identifier is 6 octets. If the interface ID of the MN is generated in the EUI-64-based format, the MN-LLA can be constructed from it. However, if the LLA is not well-known, the length of the LLA becomes ambiguous. If this is the case, it is necessary to use a new option defined in Section 6.1 and the corresponding length in it. In (b), PrRtAdv MUST include options for the LLA, IP address and prefix of the NAR. The PAR SHOULD be able to identify the NAR from the handover assist information provided by the MN. Figure 3 shows the call flow for the initial attachment in 3G CDMA network [6]. After the traffic channel is assigned, the MN first establishes a link-layer connection between itself and the access router. As the link-layer protocol, PPP can be considered and in this figure, a PPP handshake is depicted as an example. Then the MN registers with the HA by sending a Binding Update message. There are several parameters for using Mobile IPv6 such as the home address (HoA), the care-of address (CoA), the home agent address (HA) and the home link prefix (HLP). These addresses are required prior to sending a Binding Update. In [6], obtaining these values is called bootstrapping and the bootstrapping information is obtained during the link-layer establishment phase. The procedure for the initial attachment is as follows: (g) The link-layer connection establishment and the bootstrapping phase (g-1) The LCP configure-request/response messages are exchanged. (g-2) User authentication (e.g. CHAP or PAP) is conducted. (g-3) The bootstrapping parameters (e.g. HA, HLP or HoA) are conveyed from the AAA and stored in the NAR (target PDSN). (g-4) Unique interface IDs are negotiated in IPv6CP. (g-5) The MN configures its link-local address based on the obtained interface ID. (g-6) A router advertisement containing the prefix is received by the MN. (g-7) The MN configures its CoA based on the obtained prefix. Yokota & Dommety Expires January 10, 2008 [Page 10] Internet-Draft 3G CDMA Fast Handover July 2007 (g-8) DHCPv6 is used to obtain the bootstrap parameters such as the HA, HLP or HoA. (g-9) The MN configures its HoA based on the obtained parameters. If a new HoA is provided at (g-8), the MN adopts it (stateful auto-configuration); otherwise, the MN generates the HoA based on the HLP and its Interface ID (stateless auto- configuration). MN PAR NAR HA AAA / | (serving PDSN) (target PDSN) | | | | LCP | | | | | (1) |<----------------------->| | | | | CHAP/PAP | Access-Request/Accept | | (2) |<----------------------->|<-------------|------->| |+........................................+ | | | |. | | +------------+ . | | | |.(3)* | | | HA,HLP,HoA |<-------+ | |. | | +------------+ . | | |. | | . | | |. | IPv6CP(IF-ID) | . | | |.(4)* |<---------|------------->| . | | (g)< . +---------+ | | | . | | |.(5)*| LL-addr |<-+ | | . | | |. +---------+ | | . | | |. | | . | | |. | RA(prefix) | . | | |.(6)* |<---------|--------------| . | | |. +-----+ | | | . | | |.(7)*| CoA |<-----+ | | . | | |. +-----+ | | . | | |. | | . | | |. | DHCPv6(HA,HLP,HoA) | . | | |.(8)* |<---------------+------->| . | | |. +------------+ | | | . | | |.(9)*| HoA,HLP,HoA |<---+ | . | | |. +------------+ | | . | | |+........................................+ | | \ | | | | | Figure 3: Attachment procedure in 3G CDMA network As is shown in Figure 3, it takes a considerable amount of time to establish a link-layer connection and all of the above sequences run every time the MN attaches to a new access network. It is therefore beneficial if packets on the fly to the MN are saved not only during the time period where the MN switches to the new radio channel but Yokota & Dommety Expires January 10, 2008 [Page 11] Internet-Draft 3G CDMA Fast Handover July 2007 also during the time period where the MN establishes the link-layer connection. There are several ways to configure a unique IP address for the MN. If a globally unique prefix is assigned per each link as introduced in [6], the MN can use any interface ID except that of the other peer to create a unique IP address. If this is the case, however, the PAR cannot provide the MN with a correct prefix for the new network since such a prefix is selected by the NAR and provided in the router advertisement. Still, the NCoA MUST be included in the FBU for the PAR to resolve the IP address of the NAR, so that the MN configures a temporary NCoA with the prefix of the NAR and the correct NCoA MUST be assigned by the NAR. Therefore, at step (c) in Figure 2, the PAR MUST send the HI with the S flag set when it receives the FBU from the MN. On the other hand, if more than one MN connected to an AR share the same prefix, each MN MUST have a unique interface ID. Unless it is guaranteed that each MN connected to the network including a roaming case is preconfigured with a unique interface ID, it MUST be agreed or provided by the NAR via the HI/Hack exchange. In [3], the FNA MUST include the LLA of the MN, but the point-to- point link-layer connection makes it unnecessary. The only required information is the NCoA to check if there is a corresponding buffer, thus in (h), the function of the FNA can be realized in several ways. o Since the establishment of the link-layer connection in (g) indicates readiness of data communication on the MN side, the NAR immediately checks if there is a buffer that has packets destined for the NCoA and starts delivering if any. (elimination of FNA) o The FNA equivalent information can be conveyed in the phase of the link-layer connection, e.g. by conveying the NCoA in a PPP IPCP with vendor specific extension as defined in [8]. Only when this message is received by the NAR, it checks if there is a buffer for the NCoA. (L2 implementation of FNA) o The MN sends the FNA as defined in [3] with the LLA of the MN, which may be derived from the EUI-64 based interface ID. (standard implementation of FNA) When PPP IPCP option is used as the means for the L2 implementation of FNA, it SHOULD be confirmed that the NAR supports this option, otherwise it may cause a longer delay by the Configure-Reject message. The primary benefit of this mode is that the packets destined for the MN can be buffered at the NAR, and packet loss due to handover will be much lower than that of the normal MIPv6 operation. Regarding the Yokota & Dommety Expires January 10, 2008 [Page 12] Internet-Draft 3G CDMA Fast Handover July 2007 bootstrapping, the following benefits can be obtained, too: o Since the HA, HLP and HoA are not changed during the fast handover, bootstrapping information is not required. o Since the NCoA including the interface ID can be obtained or configured via the fast handover procedures, a router advertisement is not required. Therefore, the bootstrapping procedures (g-3) to (g-9) can be omitted from the standard MIPv6 operation in Figure 3. Also, if the security policy permits, the NAR can know the MN by the NAI in the PPP link setup and the authentication in (g-2) may be omitted. Note that another authentication is conducted in the MIPv6 registration phase and presumably the same AAA is referred to. 5.2. Reactive fast handover When the MN cannot receive the FBAck on the PAR's link or the network does not support the predictive fast handover, the reactive fast handover can be applied. To support the predictive fast handover, the PAR must accurately resolve the address of the NAR from the lower layer information such as the link-layer address of the new access point or the base station, which is not always feasible in some cases. To minimize packet loss in this situation, the PAR instead of the NAR can buffer packets for the MN until the MN regains connectivity with the NAR. The NAR obtains the information of the PAR from the MN on the NAR's link and receives packets buffered at the PAR. In this case, the PAR does not need to know the IP address of the NAR or the NCoA and just waits for the NAR to contact the PAR. However, since the PAR needs to know when to buffer packets for the MN, the PAR obtains the timing of buffering from the MN via the FBU or the lower layer signaling, e.g. an indication of the release of the connection with the MN. Details of the procedure are as follows: (a) A router solicitation for proxy router advertisement MAY be sent to the PAR. (b) The proxy router advertisement MAY be sent to the MN, but the prefix of the NAR MAY not be included. (c) The MN sends the FBU or the access network indicates the close of the connection with the MN by the lower layer signaling. The PAR MAY start buffering packets destined for the PCoA. (d) The link-layer connection associated with the PAR is closed and a new traffic channel is assigned in the new access network. Yokota & Dommety Expires January 10, 2008 [Page 13] Internet-Draft 3G CDMA Fast Handover July 2007 (e) The MN attaches to the new access network. The attachment procedure is access technology specific. Since the IP address of the MN is guaranteed to be unique, the MN SHOULD not perform DAD (f) The MN sends the Fast Binding Update (FBU) to the NAR either or not being encapsulated by the Fast Neighbor Advertisement (FNA). (g) The NAR decapsulates the FBU if encapsulated and sends it to the PAR. (h) The PAR sends the Handover Initiate (HI) to the NAR with the Code set to 1. (i) The NAR sends the Handover Acknowledge (HAck) back to the PAR. (j) The PAR sends the FBAck to the NAR. (k) If the PAR is buffering packets destined for the PCoA, it starts forwarding them as well as newly arriving ones to the NAR. (l) The NAR delivers the packets to the MN. (m) The MN sends the BU to the HA to update the BCE with the NCoA and the HA sends back the BA to the MN. The AAA server may be involved for authentication. Yokota & Dommety Expires January 10, 2008 [Page 14] Internet-Draft 3G CDMA Fast Handover July 2007 MN PAR NAR HA AAA | RtSolPr | | | | (a) |------------->| | | | | PrRtAdv | | | | (b) |<-------------| | | | | FBU | | | | (c) |- - - - - - ->|(buffering) | | | | | | | | (d) handover | | | | | | | | | +--------------------------------------------------------------+ (e) | Attachment procedure | +--------------------------------------------------------------+ | FNA[FBU]/FBU | | | (f) |----------------------------->| | | | | FBU | | | (g) | |<--------------| | | | | HI | | | (h) | |-------------->| | | | | HAck | | | (i) | |<--------------| | | | | FBack | | | (j) | |-------------->| | | | |forward packets| | | (k) | |==============>| | | | deliver packets | | | (l) |<=============================| | | | | BU/BA | (Authentication) (m) |<------------------------------------------->|<- - - - - - >| | | | | | Figure 4: MIPv6 Fast handover operation (reactive mode) To indicate the PAR to buffer packets destined for the PCoA, in (c), the MN SHOULD not include information on the NCoA in the FBU and the PAR SHOULD accept it. Or, when the PAR is indicated that the session with the MN has been closed by the lower layer signaling when the PAR attempts to send the FBAck, the PAR MAY start buffering. An L2-based fast handover is possible as defined in [7] by extending the L2 link from the previous access network to the new access network via the PAR and the NAR. The timing of the fast handover trigger is the same as the reactive fast handover method (without buffering) in this section. In the case of the L2-based fast handover, however, once the L2 link is extended to the new location, it is maintained until the MN becomes inactive (dormant) and the link is released. As long as the L2 link is extended, the path, on which packets are conveyed, is not optimal in length. In the case of Yokota & Dommety Expires January 10, 2008 [Page 15] Internet-Draft 3G CDMA Fast Handover July 2007 Mobile IPv6 fast handover, when the new location is registered with the HA, the packets are directed to the NAR. 5.3. Network-controlled fast handover If the lower layer can provide necessary information for handover and support handover triggering, the fast handover can also be provided to MNs that do not support FMIPv6. RtSolPr, FBU and FNA, which are initiated by the MN, may be replaced by such lower layer protocols and the fast handover can be performed without explicit involvement of the MN. This type of fast handover has been proposed, for example, in [9] and called the network-controlled fast handover in this document. The detailed sequence is shown in Figure 5. (a) The MN initiates the handover procedure with the currently connected network, which may interact with the new network. The handover intiation procedure is access technology specific. (b) The PAR (typically) sends the HI to the NAR; however, the NAR may instead send the HI to the PAR based on the lower-layer interworking. (c) The AR that received the HI sends back the HAck to the peer AR. (d) The AR that received the HAck MAY send the Unsolicited HAck to the peer AR to confirm the reception of the HAck and/or to send access technology specific information. (e) The PAR starts forwarding packets to the NAR and the NAR MAY buffers them. (f) The link-layer connection associated with the PAR is closed and a new traffic channel is assigned in the new access network. (g) The MN attaches to the new network. The attachment procedure is access technology specific. (h) The NAR starts delivering packets to the MN. (i) The MN sends the BU with the CoA being the NCoA to the HA and the HA sends back the BA to the MN after successful authentication of the BU. From this time on, the HA starts sending packets directly to the MN via the NAR. Yokota & Dommety Expires January 10, 2008 [Page 16] Internet-Draft 3G CDMA Fast Handover July 2007 MN PAR NAR HA AAA | | | | | +--------------------------------+ | | (a) | Lower-layer HO initiation | | | +--------------------------------+ | | | | HI | | | (b) | |<------/------>| | | | | HAck | | | (c) | |<------/------>| | | | | (UHAck) | | | (d) | |<- - - /- - - >| | | | |forward packets| | | (e) | |==============>|(buffering) | | | | | | | (f) handover | | | | | | | | | +--------------------------------------------------------------+ (g) | Attachment procedure | +--------------------------------------------------------------+ | deliver packets | | | (h) |<=============================| | | | | BU/BA | (Authentication) (i) |<------------------------------------------->|<- - - - - - >| | | | | | Figure 5: Network-controlled fast handover operation Even after the MN has moved to the new network, the PAR continues to send the packets to the MN by forwarding them to the NAR. The NAR is responsible for delivering packets whose destination address is the PCoA to the MN in the new network. As far as the PAR is involved, however, the path from the HA to the MN is not optimal. In order to optimize the path towards the MN, the binding cache in the HA needs to be updated. At an appropriate point after the NCoA has been assigned to the MN, the MN sends the BU to the HA to update the binding cache in the HA to the NCoA. Yokota & Dommety Expires January 10, 2008 [Page 17] Internet-Draft 3G CDMA Fast Handover July 2007 6. Message Format 6.1. New Option for access-specific handover information If the lower layer information of the new point of attachment is not represented as the Link-Layer Address, the following option SHOULD be used. The primary purpose of this option is to convey the handover assist information described in Section 4. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Option-Code | AS-Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | AS-Value... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type T.B.D. Length The size of this option in 8 octets including the Type, Length, Option-Code and AS-Length fields. Option-Code Indicates the particular type of access-specific information. This value is administrated by the vendor or organization that uses this option. AS-Length The size of the AS-Value field in octets. AS-Value Zero or more octets of access-specific information data. This option MUST be understood by the sender (typically the MN) and the receiver (typically the AR or the HA). If nodes in between do not support this option, they SHOULD treat this option as opaque and MUST not drop it. Depending on the size of the AS-Value field, appropriate padding MUST be used to ensure that the entire option size is a multiple of 8 octets. The AS-Length is used to disambiguate the size of the AS- Value. Yokota & Dommety Expires January 10, 2008 [Page 18] Internet-Draft 3G CDMA Fast Handover July 2007 7. Security Considerations The security considerations for Mobile IPv6 fast handover are described in [3]. When a 3G network is considered, the PAR and the NAR have a trusting relationship and the links between them and those between the ARs and the MN are usually secured. When the MN is authenticated at the phase of the link-layer connection, the AR can distinguish the authenticated users from the others. This may not be the case, however, if the access networks are operated by different providers. Yokota & Dommety Expires January 10, 2008 [Page 19] Internet-Draft 3G CDMA Fast Handover July 2007 8. Conclusions The handover performance of the standard Mobile IPv6 is not sufficient for real-time communications that are not resilient to packet loss. The Mobile IPv6 fast handover methods are effective for these applications. This document specifies how these methods can be applied to 3G networks. By introducing fast handover, not only are more packets saved which otherwise would be dropped, but also some of the bootstrapping parameters can be omitted at the link establishment phase, which can expedite the handover process. Yokota & Dommety Expires January 10, 2008 [Page 20] Internet-Draft 3G CDMA Fast Handover July 2007 9. References 9.1. Normative References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [2] Johnson, D., "Mobility Support in IPv6", RFC 3775, June 2004. [3] Koodli, R., Ed., "Fast Handover for Mobile IPv6", RFC 4068, July 2005. 9.2. Informative References [4] 3GPP2 TSG-A, "Interoperability Specification (IOS) for cdma2000 Access Network Interfaces Part 1 Overview", A.S0011-C v.1.0, February 2005. [5] 3GPP2 TSG-A, "3GPP2 Access Network Interfaces Interoperability Specification", A.S0001-A v.2.0, June 2001. [6] 3GPP2 TSG-X, "cdma2000 Wireless IP Network Standard: Simple IP and Mobile IP services", X.S0011-002-D v.1.0, February 2006. [7] 3GPP2 TSG-X, "cdma2000 Wireless IP Network Standard: Packet Data Mobility and Resource Management", X.S0011-003-D v.1.0, February 2006. [8] Simpson, W., "PPP Vendor Extensions", RFC 2153, May 1997. [9] 3GPP2 TSG-X, "Fast Handoff for HRPD", X.P0043 v.0.3, 2006. Yokota & Dommety Expires January 10, 2008 [Page 21] Internet-Draft 3G CDMA Fast Handover July 2007 Authors' Addresses Hidetoshi Yokota KDDI Lab 2-1-15 Ohara, Fujimino Saitama, 356-8502 JP Phone: +81 49 278 7894 Fax: +81 49 278 7510 Email: yokota@kddilabs.jp Gopal Dommety Cisco Systems, Inc. 170 West Tasman Drive San Jose, CA 95134 US Phone: +1 408 525 1404 Email: gdommety@cisco.com Yokota & Dommety Expires January 10, 2008 [Page 22] Internet-Draft 3G CDMA Fast Handover July 2007 Full Copyright Statement Copyright (C) The IETF Trust (2007). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Intellectual Property The IETF takes no position regarding the validity or scope of any Intellectual Property Rights 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; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Acknowledgment Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Yokota & Dommety Expires January 10, 2008 [Page 23]