IETF Next Steps in Signaling S. Lee Working Group J. Bang Internet-Draft B. Lee Expires: April 19, 2004 SAMSUNG AIT S. Jeong HUFS October 20, 2003 Mobility Functions in the QoS-NSLP draft-lee-nsis-mobility-nslp-00.txt 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 April 20, 2004. Copyright Notice Copyright (C) The Internet Society (2003). All Rights Reserved. Abstract The NSIS working group is standardizing a signaling protocol suite with QoS signaling as the first use case. The overall signaling protocol suite is decomposed into a generic lower layer with separate upper layers for signaling applications. The upper layer protocol, called NSIS Signaling Layer Protocol (NSLP), has an end-to-end scope and contains application specific functionality. One of the important features of an NSLP is mobility support. This document identifies desired mobility functions in an NSLP for QoS signaling (QoS-NSLP) in the network. Lee, et al. Expires April 19, 2004 [Page 1] Internet-Draft mQoS-NSLP October 2003 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Route Change and Mobility . . . . . . . . . . . . . . . . . . 5 3. Make-before-Break vs. Break-before-Make . . . . . . . . . . . 6 4. Mobility Event Detection . . . . . . . . . . . . . . . . . . . 7 5. Localized Path Repair . . . . . . . . . . . . . . . . . . . . 8 6. Route Change and Mobility . . . . . . . . . . . . . . . . . . 9 7. Support for Reservation Modes . . . . . . . . . . . . . . . . 10 8. Interaction with Mobility Protocols . . . . . . . . . . . . . 11 9. QoS Re-establishment Mechanisms in Mobile Scenarios . . . . . 13 9.1 Fast QoS Re-establishment . . . . . . . . . . . . . . . . . . 13 9.2 Fast Release of Resources . . . . . . . . . . . . . . . . . . 14 9.3 Confirmation/Error Handling . . . . . . . . . . . . . . . . . 15 10. Security Considerations . . . . . . . . . . . . . . . . . . . 16 11. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Appendix. A QoS Pre-establishment Procedures . . . . . . . . . . . 18 References . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 20 Intellectual Property and Copyright Statements . . . . . . . . 22 Lee, et al. Expires April 19, 2004 [Page 2] Internet-Draft mQoS-NSLP October 2003 1. Introduction The lower layer in the NSIS protocol suite, the NSIS Transport Layer Protocol (NTLP) is intended to provide a generally useful transport service for such signaling messages. The actual signaling messages are in general originated within upper layer signaling applications, each having its own NSIS Signaling Layer Protocol (NSLP), and the role of the NTLP is primarily just to move these messages around the network to the appropriate nodes. The general description of the NSIS protocol suite, including its two-layer architecture, can be found in [2]. One of the important features of an NSLP (in particular, an NSLP with QoS support) is mobility support. This document describes desired mobility functions in an NSLP for QoS signaling (hereafter 'QoS-NSLP') considering the mobility requirements for future signaling protocols. The main objective of the QoS-NSLP is to provide resource reservation. In this draft, only mobility-related protocol mechanisms of the QoS-NSLP are described, and the mobility functionality of the QoS-NSLP is called mQoS-NSLP. In high mobility environments, frequent handovers may result in a significant degradation of QoS performance if the wireless access network is unable to provide enhanced solutions for prompt QoS re-establishments. Therefore, one of the key features that should be supported in mQoS-NSLP is fast QoS re-establishment. The mQoS-NSLP should also support resource reservation in both sender- and receiver-oriented modes where a mobile node (MN) could be the sender or receiver. Based on these considerations, this document describes desired mobility functions for the mQoS-NSLP, including make-before-break, mobility event detection, localized path repair, state management, interaction with mobility protocols and so on. 1.1 Terminology AR: Access Router CAR: Candidate Access Router CARD: Candidate Access Router Discovery CCND: Candidate Crossover Node Discovery CN: Correspondent Node CT: Context Transfer Lee, et al. Expires April 19, 2004 [Page 3] Internet-Draft mQoS-NSLP October 2003 MN: Mobile Node mQoS-NSLP: Mobility Functionality of QoS-NSLP NE: NSIS Entity NSLP: NSIS Signaling Layer Protocol NTLP: NSIS Transport Layer Protocol OAR: Old Access Router Lee, et al. Expires April 19, 2004 [Page 4] Internet-Draft mQoS-NSLP October 2003 2. Route Change and Mobility Although the route change caused by the mobility event may be considered similar to standard route changes, the main difference is that the flow identifier does not change after the standard route change while the mobility may cause the change of the flow identifier. Therefore, the flow identifier should be updated along the entire chain of NSIS entities that are involved with the session that has been impacted by the mobility event. To update the flow identifier in an end-to-end manner, the crossover node which is the merging point of the old and new paths may decide to forward a state update message further towards the destination. The NTLP should detect any route change caused by the mobility event at transport level and triggers the mQoS-NSLP, and then the mQoS-NSLP should initiate necessary state creation (i.e., QoS re-establishment) along the new path and the update or removal of associated states, at signaling application level. Note that QoS re-establishment due to the standard route change may not need any state update along the entire signaling path since the flow identifier does not change (e.g., the IP address of endpoint does not change). The details about the route change detection procedure can be found in [21]. Lee, et al. Expires April 19, 2004 [Page 5] Internet-Draft mQoS-NSLP October 2003 3. Make-before-Break vs. Break-before-Make The act of transferring support of an MN from one AR to another is called handover. In other words, handover occurs when a flow has to be handed off from one AR to another as the MN moves. There are two possibilities for handling handover in terms of resource reservation: Make-before-Break and Break-before-Make. With Make-before-Break approach, resource reservation is set up along the new path including a new AR before releasing the resource along the old path. With Break-before-Make approach, current resource reservation is torn down before resource reservation is set up on the new path. Compared to the Break-before-Make approach, the Make-before-Break provides less QoS service disruption. In this case, however, it is necessary to provide QoS re-establishment in a very fast manner. Pre-reservation of resources or multi-homing support could be helpful for immediate QoS re-establishment after handover. In this draft, Make-before-Break approach is assumed to be used. Lee, et al. Expires April 19, 2004 [Page 6] Internet-Draft mQoS-NSLP October 2003 4. Mobility Event Detection Most of the existing approaches for signaling protocols consider only the actions which have to be taken after a handover occurs. Some newly proposed protocols use various ideas to speed up the QoS re-establishment and handle the specific mobility related events, e.g., the change of the IP address of an MN. However, most of the protocols do not introduce mechanisms for the preparation of a handover. To prepare immediate handover (i.e., for fast QoS re-establishment), the ?«MOBILITY?? object can be used by the mQoS-NSLP [15]. The ?«MOBILITY?? object contains the detailed information about the mobility event which should be used for a particular treatment by associated NSIS entities. The signaling messages can contain the MOBILITY object as an explicit indicator of any mobility event. The MOBILITY object may consist of one or more 32-bit words with a one word header. When an MN detects a handover, the mQoS-NSLP of the MN may set the MOBILITY object in the refresh message and sends it to the current AR. The mQoS-NSLP of the AR may also set the MOBILITY object after receiving the movement information generated by a mobility protocol (e.g., 'RtSolPr' message in FMIPv6 [14]) within the MN. The MOBILITY object will be delivered to involved NSIS entities along the current signaling path to inform of the mobility event. The mobility event will eventually cause a route change as the MN moves to the new AR. Lee, et al. Expires April 19, 2004 [Page 7] Internet-Draft mQoS-NSLP October 2003 5. Localized Path Repair Usually, QoS-related information is generated by an MN or CN, and sent to a peer representing the opposite terminating point of the path. The paths in a mobility supporting access network usually change only partially. Therefore, the mQoS-NSLP should support localized path repair to avoid end-to-end signaling message exchanges which may incur a long delay. In other words, the mQoS-NSLP needs to limit the scope of signaling information to a section of the signaling path. This is referred to as localized signaling. The localized QoS signaling can be initiated by the NSIS-aware merging point of the old and new paths, which is sometimes called crossover node. After the crossover node is determined by the NTLP [21], the mQoS-NSLP should be notified of the crossover determination to re-install reservation states along the new path and to remove old reservation states along the old path. If the Old AR is the last node due to handover, the mQoS-NSLP of the NE in the old AR may trigger an error message to indicate that no more mQoS-NSLP messages will be forwarded to the last node (e.g., the MN). However, the states along the old path must not be deleted before re-establishing the state along the new path although the error message is initiated. Lee, et al. Expires April 19, 2004 [Page 8] Internet-Draft mQoS-NSLP October 2003 6. Route Change and Mobility The soft state similar to RSVP may need to be maintained to manage the reservation state at the NEs in the crossover node, routers, and MNs. On receiving a resource reservation message, an NE (specifically the mQoS-NSLP) sets up state for fast reservation. This state is deleted unless it is refreshed by a new resource reservation message before the refresh timer expires. It may be necessary to set the refresh timer value in a wireless network to a smaller value than that in the core (wired) network [6]. The main objective of adjustment of the refresh timer value is to minimize the unnecessary waste of resources. To do this, NEs can appropriately set the refresh interval suitable for their own environments in a peer-to-peer manner. Setting the timer value of the access network differently from that of the backbone network can be done by manual configuration or some adaptive technique. An example of adaptive technique may be to use the 'Refresh' object by defining the 'M' bit for mobility and the 'PRE' bit for fast re-establishment. In mobile and wireless networks, it may be desirable that the mQoS-NSLP can set its refresh timer value (by setting the M bit to 1) appropriately depending on the part of the network (e.g., an access network or backbone network). On receiving the MOBILITY object during handover, the mQoS-NSLP of candidate NEs which are supposedly involved in the QoS signaling application sets the 'RFE' bit of outgoing mQoS-NSLP messages (Refresh object) for fast QoS re-establishment. For instance, pre-reservation state may be maintained for a short period of time. To do this, the mQoS-NSLP of the involved NEs may set the 'PRE' bit to 1, and a pre-reservation state may be temporarily maintained to avoid the excessive waste of resources until the handover is completed. After handover, the PRE bit is reset to 'null' to reduce the overhead due to frequent transmission of refresh messages, and 'M' bit is kept to be '1' (see Section 9.1 and Appendix A for more details)[15]. Lee, et al. Expires April 19, 2004 [Page 9] Internet-Draft mQoS-NSLP October 2003 7. Support for Reservation Modes The mQoS-NSLP should be able to support resource reservation in both sender- and receiver-oriented modes where the MN could be the sender or receiver. With the sender-initiated approach, the MN (as a sender) can initiate a reservation setup for its outgoing flows as soon as it has moved toward another AR. With the receiver-initiated approach, the MN (as a sender) somehow has to inform the receiver of its handover, thus allowing the receiver to initiate a reservation for the flows. This delayed signaling problem in the receiver-initiated approach can be solved in a way similar to the fast re-establishment using the CT as described in Section 9.1. In addition to the unidirectional reservation above, the mQoS-NSLP should also support bidirectional reservation setup. With this bidirectional reservation setup, the state for bidirectional data flows is setup. In the basic case, bidirectional QoS signaling can simply use a separate instance of the same signaling mechanism in each direction. The bidirectional data flows have the same end points, but the path in the two directions does not need to be the same. In this case, there are a few merging points that downstream state of reservation and upstream state of reservation meet. Therefore, a crossover node for downstream reservation may be different from that for upstream reservation when the MN reaches a new attachment point of the network, i.e., a new AR. As a matter of course, the Session ID in the downstream reservation must be different from that of the upstream reservation. If the routes (i.e., upstream and downstream paths) are symmetric, a single signaling message can be used to set up reservation in both directions. If the routes are asymmetric, a signaling message from the originator (e.g., MN or CN) should trigger an independent signaling message from the responder. The correlation of the signaling for the two flow directions is carried out in the mQoS-NSLP. The NTLP would simply be enabled to bundle the messages together. Lee, et al. Expires April 19, 2004 [Page 10] Internet-Draft mQoS-NSLP October 2003 8. Interaction with Mobility Protocols As mentioned in Section 4, the mQoS-NSLP of an NE may be able to interwork with mobility protocols using the movement detection. The movement of an MN should be detected first by the NTLP of an MN or AR. The mQoS-NSLP is then triggered by the NTLP to act appropriately. The mQoS-NSLP may set the MOBILITY object of an outgoing QoS-NSLP message for fast QoS state re-establishment. This MOBILITY object can be used to find a crossover node or set the 'Refresh' object for changing the timer value. Seamless Mobility protocols Such as CARD and CT can be used to fast re-establish the mQoS-NSLP state after handover (or during handover). For fast re-establishment, the possible interaction scenarios with the seamless mobility protocols are as follows. When a handover is initiated, the current AR receiving the movement detection information from an MN may be able to use the CARD mechanism to find an appropriate access router (an NSIS aware node) before the handover is completed, and as a result a few candidate access routers (CARs) may be found. In this process, the AR should be able to recognize whether the CARs are NSIS-aware node after sending the 'capability reply' message (of CARD). The mQoS-NSLP of the AR may need to be interaction with the CT protocol to transfer the mQoS-NSLP state information for mQoS-NSLP state establishment to the newly discovered NSIS-aware candidate ARs. After receiving the context, NTLPs of the candidate ARs may be able to begin to trigger a candidate crossover node discovery mechanism using the mQoS-NSLP state information [21]. The crossover node discovery can be initiated during handover (i.e., before the handover is completed), for instance, for fast QoS re-establishment or pre-reservation. However, in this case, an efficient mechanism is needed to find a candidate crossover node. CARD and CR mechanisms can be used for this purpose. A candidate crossover node can be found easily since the candidate crossover node discovery is basically the same as the normal crossover node discovery. In response to the peer discovery request message, the candidate crossover node sends an acknowledgement message to its peer node. In some cases, however, it may not be possible to use mobility related protocols such as CT and CARD. In this case, the MN can initiate the crossover node discovery only after it arrives at a new AR. To expedite the discovery process, it may be useful to transmit the peer discovery message (by the NTLP) and the binding update message at the same time. To immediately re-establish the mQoS-NSLP state after handover, the mQoS-NSLP should interwork with handover information (e.g., Binding Lee, et al. Expires April 19, 2004 [Page 11] Internet-Draft mQoS-NSLP October 2003 Update message in MIPv6). For instance, on receiving the handover information, mQoS-NSLP can set the 'M' bit of 'Refresh' bits to appropriately adjust the refresh timer for an access network and quickly trigger the peer discovery of NTLP. Lee, et al. Expires April 19, 2004 [Page 12] Internet-Draft mQoS-NSLP October 2003 9. QoS Re-establishment Mechanisms in Mobile Scenarios A route change due to mobility may cause the obsolete paths of mQoS-NSLP and may also cause the service disruption due to re-establishment of the mQoS-NSLP state. Therefore, it is required to immediately re-establish the same state of the mQoS-NSLP and afterwards to delete the obsolete paths quickly after handover [1]. The subsequent sections describe QoS re-establishment mechanisms in mobile scenarios in further detail. 9.1 Fast QoS Re-establishment This section considers two possible mechanisms to quickly re-establish reservation of resources along the new path after handover: Pre-establishment and Fast re-establishment [15]. The pre-establishment approach is used to reserve resources in areas which the MN may visit to support seamless QoS services. Although the NSIS requirement draft describes only QoS re-establishment after handover [1], the pre-establishment is a desirable feature to guarantee the seamless QoS services. On the other hand, the fast re-establishment approach is used to quickly set up reservation of resources along the new path to minimize the disruption of QoS services after handover. To carry out the pre-establishment mechanism, NEs may interwork with seamless mobility protocols (e.g., CARD and CT) as mentioned in Section 8 and use the CCND to localize the pre-establishment. The refresh timer value may also be optimized to avoid unnecessary pre-reservation (see Appendix A for further details). If pre-establishment is not used (or if pre-establishment of the mQoS-NSLP fails due to the lack of available resources or the failure of NEs along the new path), the NEs are responsible for fast re-establishing the mQoS-NSLP state after handover. The key ideas of the fast re-establishment are to transfer the mQoS-NSLP state to candidate NEs between a CCN and CARs by the CT before handover and to localize the re-establishment after handover. With the context transfer approach described above, the candidate NEs try to distribute the information of mQoS-NSLP state or continuously maintain the state until the pre-establishment succeeds before the completion of handover. The candidates can learn the mQoS-NSLP state from the By-the-CT approach in this way. For example, if the MN acts as a sender in the sender-initiated approach, the CAR may be used to establish the mQoS-NSLP state by sending a reservation message where the 'PRE' bit is set or to Lee, et al. Expires April 19, 2004 [Page 13] Internet-Draft mQoS-NSLP October 2003 transfer the context related to the mQoS-NSLP state toward the CCN during the handover. In this way, the candidate NEs between CAR and CCN can recognize the state information. It is also possible that the MN may initiate a reservation message after handover. In this case, the associated NEs can establish the mQoS-NSLP states more quickly since the mQoS-NSLP only needs to update the changed information (e.g., refresh timer value, flow ID, and so on)[17]. If the MN acts as a receiver, the CCN also uses the same process toward the CARs as the MN as a sender. If the CCN fails to transfer the states, the crossover node triggers a reservation message where the 'M' bit is set to establish the mQoS-NSLP state after receiving the handover information (e.g., a BU message). In order to fast re-establish the mQoS-NSLP states in the receiver-initiated approach, a path state should be established first. If the MN acts as a receiver, the mQoS-NSLP of the CCN needs to first establish the path state toward the CAR using in a peer-to-peer manner, and afterwards the MN can quickly reserve the resources by only sending a reservation message to the crossover node as soon as a path setup message is received after handover. If the MN acts as a sender, the CAR pre-establishes the path state up to the CCN. After handover, the mQoS-NSLP of the MN sends a path setup message where the 'M' bit is set toward the crossover node but the NEs on the new path only update changed information (e.g., refresh timer value, flow ID, mQoS-NSLP SPEC, and so on). As a result, the mQoS-NSLP state can be re-established quickly. If the CARD and the CT are not able to interwork with NTLP/mQoS-NSLP nor operate correctly, the re-establishment of the mQoS-NSLP state should be localized to minimize the disruption of QOS services. In this case, the mQoS-NSLP states are only re-established by the same method that the existing sender-initiated and receiver-initiated approaches operate without pre-establishment after handover. In this case, mQoS-NSLP messages should be transmitted simultaneously with Handover information (e.g., Biding Update message in MIPv6) even if NTLP and mQoS-NSLP do not have any interaction with mobility protocols as described in Section 8. 9.2 Fast Release of Resources As in RSVP, reservation states may be explicitly torn down when a flow terminates or when the admission control rejects a reservation. In addition, it is needed to release the previously reserved resources along the old path immediately after establishing the state Lee, et al. Expires April 19, 2004 [Page 14] Internet-Draft mQoS-NSLP October 2003 of QoS NSLP along new paths due to handover. To release the previously reserved resources along the old path after handover, a crossover node first needs to receive a teardown message (or a reservation message) from the MN which arrived at a new AR. On receiving the teardown message, NSLP on the crossover node immediately updates reservation states of the old session and simultaneously transmits a reservation a Reserve message toward the old AR to delete the state of the mQoS-NSLP along the old paths. 9.3 Confirmation/Error Handling As in RSVP, the MN can send a request for confirmation for its reservation request. In this case, the request for confirmation is included in the resource reservation messages. If any reservation fails, a reservation error message will be delivered to the MN. The reservation error message may contain enough information so that the MN can decide its future direction. If the Old AR is the last node after handover, the mQoS-NSLP of NE in the old AR may trigger an error message that indicates that no more NSLP messages are forwarded the last node. However, the states along the old paths must not be deleted before establishing the state along the new paths due to this error message. Lee, et al. Expires April 19, 2004 [Page 15] Internet-Draft mQoS-NSLP October 2003 10. Security Considerations The mQoS-NSLP relies on the security mechanisms described in [4]. Securing the mQoS-NSLP is provided by CMS which allows resource objects and related objects defined in this document to be encapsulated and protected by CMS. Therefore, no separate specification within the mQoS-NSLP is necessary to describe the format of these objects. This allows some flexibility in including protected objects to link the authorization step of different protocols and to transport local information within domains. The functionality described in [19] and [20] can be provided without substantial protocol modification/extensions. Lee, et al. Expires April 19, 2004 [Page 16] Internet-Draft mQoS-NSLP October 2003 11. Conclusion This document described the mobility functionality of the QoS-NSLP, including make-before-break, localized path repair, state management, unidirectional and bidirectional reservation support, interaction with mobility protocols, and so on. Lee, et al. Expires April 19, 2004 [Page 17] Internet-Draft mQoS-NSLP October 2003 Appendix. QoS Pre-establishment Procedures The pre-establishment mechanism may consist of three general operations for seamless handover [9] [10] and two main operations for QoS re-establishment: Movement Detection, Candidate Access Router Discovery (CARD), Context Transfer (CT), Candidate Crossover Node Discovery (CCND), and reservation setup. As mentioned in Section 4, a handover initiator (e.g., an MN or an AR) notifies the NE within the AR of the mobility event. In this case, the mQoS-NSLP of the NE constitutes the MOBILITY object, and should not delete the existing state along the old path even if the error message indicating the 'Can-Not-Be-Forwarded-to-the-LAST-NODE' is issued (see Section 5). After receiving the handover initiation information, the mQoS-NSLP/NTLP in the AR transfers its state information (such as the session identifier, flow identifiers, MOBILITY object, security-related information, and so on) to NSIS-aware CARs through interworking with CARD and CT as mentioned Section 8. After receiving the context, the NTLP in the candidate AR begins to trigger the CCND mechanism [21] based on the NTLP/mQoS-NSLP state information to localize pre-establishment. Before pre-establishment, the mQoS-NSLP of candidate ARs and a CCN need to reset the soft state refresh timer to the optimized value by the 'PRE' bit to utilize the resource efficiently. For example, if the refresh timer value in the pre-establishment phase is set to a little higher value than the estimated handover latency, the MN can received seamless QoS Services by the pre-reserved resources, and resources which are pre-reserved but unused will be automatically released after timeout. After handover is completed, the mQoS-NSLP should restore the original refresh timer value in order to avoid frequent transmission of refresh messages (as mentioned in Section 6). If the sender-initiated approach is used for pre-reservation and an MN acts as a sender (or a receiver), the CARs (or the CCN(s)) reserve resources in advance by sending a reservation message toward the CCN(s) (or the CARs). On the other hand, if the receiver-initiated approach is used and an MN is a sender (or receiver), the opposite operation is performed. To distinguish pre-establishment signaling messages from re-establishment signaling messages, the 'PRE' bit of the 'Refresh' object may be also used. Finally, mQoS-NSLP states between CCN and CAR will be pre-established, and the MN arriving at a new AR can receive QoS service immediately. Lee, et al. Expires April 19, 2004 [Page 18] Internet-Draft mQoS-NSLP October 2003 References [1] Brunner, M., "Requirements for Signaling Protocols", draft-ietf-nsis-req-09 (work in progress), August 2003. [2] Hancock, R., "Next Steps in Signaling: Framework", draft-ietf-nsis-fw-04 (work in progress), September 2003. [3] Chaskar, H., "Requirements of a Quality of Service (QoS) Solution for Mobile IP", RFC 3583, September 2003. [4] Schulzrinne, H., "CASP - Cross-Application Signaling Protocol", draft-schulzrinne-nsis-casp-01 (work in progress), March 2003. [5] Schulzrinne, H., "A Quality-of-Service Resource Allocation Client for CASP", draft-schulzrinne-nsis-casp-qos-01 (work in progress), March 2003. [6] McDonald, A., "A Quality of Service NSLP for NSIS", draft-mcdonald-nsis-qos-nslp-00 (work in progress), June 2003. [7] Bosch, S., "NSLP for Quality-of-Service signaling", draft-ietf-nsis-qos-nslp-00 (work in progress), September 2003. [8] Schulzrinne, H., "GIMPS: General Internet Messaging Protocol for Signaling", draft-schulzrinne-nsis-ntlp-00 (work in progress), June 2003. [9] Loughney, J., "Context Transfer Protocol", draft-ietf-seamoby-ctp-04 (work in progress), October 2003. [10] Liebsch, M., "Candidate Access Router Discovery", draft-ietf-seamoby-card-protocol-04 (work in progress), September 2003. [11] Tschofenig, H. and D. Kroeselberg, "Security Threats for NSIS", draft-ietf-nsis-threats-02 (work in progress), July 2003. [12] Buchli, M., "A Network Service Layer Protocol for QoS signaling", draft-buchli-nsis-nslp-00 (work in progress), June 2003. [13] Fu, X., "Mobility Support in NSIS", draft-fu-nsis-mobility-00 (work in progress), June 2003. [14] Koodli, R., "Fast Handovers for Mobile IPv6", draft-ietf-mobileip-fast-mipv6-08 (work in progress), October 2003. Lee, et al. Expires April 19, 2004 [Page 19] Internet-Draft mQoS-NSLP October 2003 [15] Lee, S., "QoS Signaling for IP-based Radio Access Networks", draft-lee-nsis-signaling-ran-00 (work in progress), June 2003. [16] Braden, B., Zhang, L., Berson, S., Herzog, S. and S. Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1 Functional Specification", RFC 2205, September 1997. [17] Berger, L., Gan, D., Swallow, G., Pan, P., Tommasi, F. and S. Molendini, "RSVP Refresh Overhead Reduction Extensions", RFC 2961, April 2001. [18] Westberg, L., "A Proposal for RSVPv2", draft-westberg-proposal-for-rsvpv2-01 (work in progress), November 2002. [19] Hamer, L-N., Gage, B. and H. Shieh, "Framework for Session Set-up with Media Authorization", RFC 3521, April 2003. [20] Hamer, L-N., Gage, B., Kosinski, B. and H. Shieh, "Session Authorization Policy Element", RFC 3520, April 2003. [21] Jeong, S., "Mobility Functions in the NTLP", draft-jeong-nsis-mobility-ntlp-00 (work in progress), October 2003. Authors' Addresses Sung-Hyuck Lee SAMSUNG Advanced Institute of Technology i-Networking Lab. San 14-1, Nongseo-ri, Giheung-eup Yongin-si, Gyeonggi-do 449-712 KOREA Phone: +82 31 280 9585 EMail: starsu.lee@samsung.com Jongho Bang SAMSUNG Advanced Institute of Technology i-Networking Lab. San 14-1, Nongseo-ri, Giheung-eup Yongin-si, Gyeonggi-do 449-712 KOREA Phone: +82 31 280 9585 EMail: jh0278.bang@samsung.com Lee, et al. Expires April 19, 2004 [Page 20] Internet-Draft mQoS-NSLP October 2003 Byoung-Joon Lee SAMSUNG Advanced Institute of Technology i-Networking Lab. San 14-1, Nongseo-ri, Giheung-eup Yongin-si, Gyeonggi-do 449-712 KOREA Phone: +82 31 280 9626 EMail: bj33.lee@samsung.com Seong-Ho Jeong Hankuk University of FS 89 Wangsan Mohyun Yongin-si, Gyeonggi-do 449-791 KOREA Phone: +82 31 330 4642 EMail: shjeong@hufs.ac.kr Lee, et al. Expires April 19, 2004 [Page 21] Internet-Draft mQoS-NSLP October 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. Copies of claims of rights made available for publication 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 implementors or users of this specification can be obtained from the IETF Secretariat. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights which may cover technology that may be required to practice this standard. Please address the information to the IETF Executive Director. Full Copyright Statement Copyright (C) The Internet Society (2003). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assignees. 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 Lee, et al. Expires April 19, 2004 [Page 22] Internet-Draft mQoS-NSLP October 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. Lee, et al. Expires April 19, 2004 [Page 23] IETF Next Steps in Signaling S. Lee Working Group SAMSUNG AIT Internet-Draft S. Jeong Expires: April 26, 2004 HUFS J. Bang BJ Lee SAMSUNG AIT October 27, 2003 Mobility Functions in the QoS-NSLP draft-lee-nsis-mobility-nslp-01.txt 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 April 26, 2004. Copyright Notice Copyright (C) The Internet Society (2003). All Rights Reserved. Abstract The NSIS working group is standardizing a signaling protocol suite with QoS signaling as the first use case. The overall signaling protocol suite is decomposed into a generic lower layer with separate upper layers for signaling applications. The upper layer protocol, called NSIS Signaling Layer Protocol (NSLP), has an end-to-end scope and contains application specific functionality. One of the important features of an NSLP is mobility support. This document identifies desired mobility functions in an NSLP for QoS signaling (QoS-NSLP) in Lee, et al. Expires April 26, 2004 [Page 1] Internet-Draft mQoS-NSLP October 2003 the network. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Route Change and Mobility . . . . . . . . . . . . . . . . . . 5 3. Make-before-Break vs. Break-before-Make . . . . . . . . . . . 6 4. Actions Triggered by a Mobility Event . . . . . . . . . . . . 7 5. Localized Path Repair . . . . . . . . . . . . . . . . . . . . 8 6. State management . . . . . . . . . . . . . . . . . . . . . . . 9 7. Support for Reservation Modes . . . . . . . . . . . . . . . . 10 8. Interactions with Mobility Protocols . . . . . . . . . . . . . 11 9. QoS Re-establishment Mechanisms in Mobile Scenarios . . . . . 13 9.1 Fast QoS Re-establishment . . . . . . . . . . . . . . . . . . 13 9.2 Fast Release of Resources . . . . . . . . . . . . . . . . . . 14 9.3 Confirmation/Error Handling . . . . . . . . . . . . . . . . . 15 10. Security Considerations . . . . . . . . . . . . . . . . . . . 16 11. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Appendix A. QoS Pre-establishment Procedures . . . . . . . . . . . 18 References . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 20 Intellectual Property and Copyright Statements . . . . . . . . 22 Lee, et al. Expires April 26, 2004 [Page 2] Internet-Draft mQoS-NSLP October 2003 1. Introduction The general description of the NSIS protocol suite, including its two-layer architecture, can be found in [2]. The lower layer in the NSIS protocol suite, the NSIS Transport Layer Protocol (NTLP) is intended to provide a generally useful transport service for such signaling messages. The actual signaling messages are in general originated within upper layer signaling applications, each having its own NSIS Signaling Layer Protocol (NSLP). One of the important features of an NSLP (in particular, NSLP for QoS support) is mobility support. This document identifies desired mobility functions in the QoS-NSLP [7] whose main objective is provide resource reservation according to the mobility requirements for future signaling protocols. The mobility functions in this document refer to the functions which are used to support mobility in NSIS signaling. In this document, only mobility-related protocol mechanisms of the QoS-NSLP are discussed, and the mobility functionality of the QoS-NSLP is called mQoS-NSLP. In high mobility environments, frequent handovers may result in a significant degradation of QoS performance if the wireless access network is unable to provide enhanced solutions for prompt QoS re-establishment. Therefore, one of the key features that should be supported in mQoS-NSLP is fast QoS re-establishment. The mQoS-NSLP should also support resource reservation in both sender- and receiver-oriented modes where a mobile node (MN) may act as a sender or receiver. Based on these considerations, this document discusses desired mobility functions for the mQoS-NSLP, including make-before-break, mobility event detection, localized path repair, state management, interaction with mobility protocols, and so on. 1.1 Terminology AR: Access Router CAR: Candidate Access Router CARD: Candidate Access Router Discovery CCND: Candidate Crossover Node Discovery CN: Correspondent Node CRN: Crossover Node Lee, et al. Expires April 26, 2004 [Page 3] Internet-Draft mQoS-NSLP October 2003 CT: Context Transfer MN: Mobile Node mQoS-NSLP: Mobility Functionality of QoS-NSLP NE: NSIS Entity NSLP: NSIS Signaling Layer Protocol NTLP: NSIS Transport Layer Protocol NAR: New Access Router OAR: Old Access Router Lee, et al. Expires April 26, 2004 [Page 4] Internet-Draft mQoS-NSLP October 2003 2. Route Change and Mobility Although the route change caused by a mobility event may be considered similar to standard route changes, the main difference is that the flow identifier may not change after the normal route change (e.g., due to link or node failure) while the mobility may cause the change of the flow identifier. Therefore, the flow identifier should be updated along the entire chain of NSIS entities that are involved with the session that has been impacted by the mobility event. To update the flow identifier in an end-to-end manner, the crossover node (CRN) which is the merging point of the old and new paths may decide to forward a state update message further towards the destination. The NTLP should detect any route change caused by the mobility event at transport level and triggers the mQoS-NSLP, and then the mQoS-NSLP should initiate necessary state creation (i.e., QoS re-establishment) along the new path and the update or removal of associated states, at signaling application level. Note that QoS re-establishment due to the standard route change may not need any state update along the entire signaling path since the flow identifier does not change (e.g., the IP address of endpoint does not change). The details about the route change detection procedure can be found in [24]. Lee, et al. Expires April 26, 2004 [Page 5] Internet-Draft mQoS-NSLP October 2003 3. Make-before-Break vs. Break-before-Make The act of transferring support of an MN from one AR to another is called handover. In other words, handover occurs when a flow has to be handed off from one AR to another as the MN moves. There are two possibilities for handling handover in terms of resource reservation: Make-before-Break and Break-before-Make. With the Make-before-Break approach, resource reservation is set up along the new path including a new AR before releasing the resource along the old path. On the other hand, with the Break-before-Make approach, current resource reservation is torn down before resource reservation is re-setup on the new path. Compared to the Break-before-Make approach, the Make-before-Break provides less QoS service disruption. In this case, however, it is necessary to support QoS re-establishment in a very fast manner. Pre-reservation of resources or multi-homing support could be helpful for immediate QoS re-establishment after handover is initiated. In the Make-before-Break approach which is assumed to be used in this document, the mQoS-NSLP of the CRN will play a significant role in QoS re-establishment because the CRN will be the appropriate node to initiate a new reservation state installation. Lee, et al. Expires April 26, 2004 [Page 6] Internet-Draft mQoS-NSLP October 2003 4. Actions Triggered by a Mobility Event In this section, we identify possible actions triggered by a mobility event. After a mobility event such as a handover is detected by the NTLP (e.g., using the Fast MIPv6 protocol), the mQoS-NSLP may need to initiate necessary actions such as immediate QoS re-establishment on the new path and release of resources on the old path. To support seamless handover (i.e., immediate QoS re-establishment), the MOBILITY object may be defined in the mQoS-NSLP message [15]. The MOBILITY object may contain various mobility-related fields such as the handover_init field and 'REFRESH' field. This handover_init field may be used to notify of handover initiation or any other mobility events, and therefore determine the appropriate time at which QoS re-establishment can be initiated by an NSIS node (e.g., the CRN). The REFRESH field can be used to explicitly notify of the change of state for fast state re-establishment (see Section 6). In other words, the MOBILITY object may act as an explicit indicator of a mobility event for fast QoS re-establishment. In addition, the CRN can regonize that the QoS re-establishment should be made on the local segment (e.g., MN-to-NAR) of the signaling path when receiving the MOBILITY object. The MOBILITY object may consist of one or more 32-bit words with a one word header as in RSVP [16]. The MOBILITY object may also be defined in the NTLP in a similar way. In this case, there should be some relationship between the MOBILITY objects of the NTLP and the NSLP. When an MN detects a handover, the mQoS-NSLP of the MN may set the MOBILITY object in the mQoS-NSLP signaling message and send it to the current AR, or the mQoS-NSLP of the AR may set the MOBILITY object after receiving the movement information generated by a mobility protocol (e.g., 'RtSolPr' message in FMIPv6 [14]). The MOBILITY object will be delivered to involved NSIS entities along the current signaling path to inform of the mobility event. The MOBILITY object will eventually cause the interaction with the seamless mobility protocols (e.g., CARD and CT), furthermore it can be used to appropriately adjust the value of refresh timer to minimize the waste of resources (see Sections 6 and 9). Lee, et al. Expires April 26, 2004 [Page 7] Internet-Draft mQoS-NSLP October 2003 5. Localized Path Repair In general, the mQoS-NSLP related information is generated by an MN or CN, and sent to the opposite terminating point of the path. However, the paths in a mobility supporting access network usually change only partially. Therefore, the mQoS-NSLP should support localized path repair to avoid end-to-end signaling message exchanges which may incur a long delay. In other words, the mQoS-NSLP needs to limit the scope of signaling information to a local section of the signaling path. This is referred to as localized signaling in this document. The localized QoS signaling can be initiated by the NSIS-aware merging point of the old and new paths, which is sometimes called crossover node (CRN). After the CRN is determined by the NTLP (see Section 4 in [24]), the mQoS-NSLP should be notified of the CRN determination to quickly re-install reservation states along the new path and to remove old reservation states on the obsolete path to avoid double reservation and to increase resource utilization. In the localized path repair scenarios, the CRN may play the role of an NI, NF, or NR. For example, if an MN is receiver, the CRN may need to act as an NI to initiate QoS re-establishment on the new path and remove the old states on the obsolete path. if an MN is sender, the CRN may need to act as an NR to respond to the signaling initiation message from the MN and act as an NI to remove the old states on the obsolete path. Therefore, there may need to be some transitions between the operation modes of the CRN depending on the situation. If the old AR is the last node due to handover, the mQoS-NSLP of the old AR may trigger an error message to indicate that mQoS-NSLP messages can not be forwarded any further. The error message may cause the removal of the old states. However, in the case, the states along the old path must not be deleted before re-establishing the states along the new path although the error message is initiated. Lee, et al. Expires April 26, 2004 [Page 8] Internet-Draft mQoS-NSLP October 2003 6. State management The soft state similar to RSVP may need to be maintained to manage the reservation state at the NEs in the CRN, routers, and MNs. On receiving a resource reservation message, an NE (specifically the mQoS-NSLP) sets up state for fast reservation. This state is deleted unless it is refreshed by a new resource reservation message before the refresh timer expires. It may be necessary to set the refresh timer value in a wireless network to a smaller value than that in the core (wired) network [6]. The main objective of adjustment of the refresh timer value is to minimize the unnecessary waste of resources. To do this, the mQoS-NSLP of NEs may appropriately set the refresh interval considering network environments in a peer-to-peer manner. Setting the timer value of the access network differently from that of the backbone network can be done by manual configuration or some adaptive techniques. An example of such adaptive techniques may be to use the 'REFESH' field of the MOBILITY object where the 'M' bit is defined to indicate the type of network (e.g., the mobility-supporting access network) and the 'PRE' bit is defined for fast QoS re-establishment. In mobile and wireless networks, it may be desirable that the mQoS-NSLP can set its refresh timer value (by setting the M bit to '1') appropriately depending on the part of the network (e.g., an access network or backbone network). Upon receiving the MOBILITY object during handover, the mQoS-NSLP of candidate NEs which are supposedly involved in the QoS signaling application sets the 'PRE' bit of outgoing mQoS-NSLP messages for fast QoS re-establishment. For instance, pre-reservation state may need to be maintained for a short period of time. To do this, the mQoS-NSLP of the involved NEs may set the 'PRE' bit to 1, and a pre-reservation state may be temporarily maintained to avoid the waste of resources until the handover is completed. After handover, the PRE bit is reset to 'null' to reduce the overhead due to frequent transmission of refresh messages, and 'M' bit is kept to be '1' (see Section 9.1 and Appendix A for more details)[15]. Lee, et al. Expires April 26, 2004 [Page 9] Internet-Draft mQoS-NSLP October 2003 7. Support for Reservation Modes The mQoS-NSLP should be able to support resource reservation in both sender- and receiver-oriented modes where the MN could be the sender or receiver. With the sender-initiated approach, the MN (as a sender) can initiate a reservation setup for its outgoing flows as soon as it has moved to a new AR. With the receiver-initiated approach, the MN (as a sender) somehow has to inform the receiver of its handover, thus allowing the receiver to initiate a reservation for the flows. This delayed signaling problem in the receiver-initiated approach can be solved in a way similar to the fast re-establishment using the Candidate Access Router Discovery [10] and Context Transfer [9] as described in Section 9.1. In addition to the unidirectional reservation above, the mQoS-NSLP should also support bidirectional reservation setup. With this bidirectional reservation setup, the state for bidirectional data flows is setup. In the basic case, bidirectional QoS signaling can simply use a separate instance of the same signaling mechanism in each direction. Although the bidirectional data flows have the same end points, the path in the two directions does not need to be the same. In this case, there are a few merging points that the downstream state of reservation and the upstream state of reservation meet. Therefore, the CRN for the downstream reservation may be different from that for the upstream reservation when the MN reaches a new attachment point of the network. As a matter of course, the Session ID in the downstream reservation must be different from that of the upstream reservation. If the routes (i.e., upstream and downstream paths) are symmetric, a single signaling message can be used to set up reservation in both directions. If the routes are asymmetric, a signaling message from the originator (e.g., MN or CN) should trigger an independent signaling message from the responder. The correlation of the signaling for the two flow directions is carried out in the mQoS-NSLP. Lee, et al. Expires April 26, 2004 [Page 10] Internet-Draft mQoS-NSLP October 2003 8. Interactions with Mobility Protocols As mentioned in Section 4, the mQoS-NSLP of an NE may be able to interwork with mobility protocols using the movement detection. The movement of an MN should be detected first by the NTLP of an MN or AR. The mQoS-NSLP is then triggered by the NTLP to act appropriately. The mQoS-NSLP may set the MOBILITY object of an outgoing QoS-NSLP message for fast QoS state re-establishment. This MOBILITY object can be used to find a CRN or set the 'REFRESH' field for changing the value of refresh timer. Although NSIS is focused on Path-coupled signaling, interactions with path-decoupled signaling protocols such as seamless mobility protocols (e.g., CARD and CT) may be needed to fast re-establish the mQoS-NSLP state or check resource avability on the new path after handover (or during handover). For fast re-establishment, the possible interaction scenarios with the seamless mobility protocols are as follows. When a handover is initiated, the current AR receiving the movement detection information (e.g., 'RtSolPr' message in FMIPv6 [14]) from an MN may interact with the CARD mechanism to find an appropriate access router (an NSIS aware node) before the handover is completed (or, a few candidate access routers (CARs) may be found). In this process, the NTLP of the current AR should be able to recognize whether the CAR is an NSIS-aware node after sending the 'capability reply' message (of CARD). The mQoS-NSLP of the AR may need to be interaction with the CT protocol to transfer the mQoS-NSLP state information to the newly discovered NSIS-aware candidate AR. After receiving the context, the NTLP of the candidate AR may be able to begin to trigger a candidate crossover node discovery (CCND) mechanism using the mQoS-NSLP state information [24]. The CRN discovery can be initiated during handover (i.e., before the handover is completed), for instance, for fast QoS re-establishment or pre-reservation. However, in this case, an efficient mechanism is needed to find a candidate crossover node. CARD and CT mechanisms can be used for this purpose. A candidate crossover node can be found easily since the candidate crossover node discovery is basically the same as the normal crossover node discovery [24]. In response to a peer discovery request message, the candidate crossover node sends an acknowledgement message to its peer node. In some cases, however, it may not be possible to use mobility related protocols such as CT and CARD. In this case, the MN can initiate the crossover node discovery only after it arrives at a new AR. To expedite the discovery process, it may be useful to transmit the peer discovery message (by the NTLP) and the first binding update message at the same time. Lee, et al. Expires April 26, 2004 [Page 11] Internet-Draft mQoS-NSLP October 2003 To immediately re-establish the mQoS-NSLP state after handover, the mQoS-NSLP may need to monitor handover information (e.g., Binding Update messages in MIPv6). For instance, on receiving the handover information, mQoS-NSLP can set the 'M' bit of 'REFRESH' field to appropriately adjust the value of refresh timer suitable for an access network and quickly trigger the peer discovery of NTLP. Lee, et al. Expires April 26, 2004 [Page 12] Internet-Draft mQoS-NSLP October 2003 9. QoS Re-establishment Mechanisms in Mobile Scenarios A route change due to mobility may cause the obsolete paths of mQoS-NSLP and may also cause the service disruption due to re-establishment of the mQoS-NSLP state. Therefore, it is required to immediately re-establish the same state of the mQoS-NSLP on the new path and afterwards to delete the obsolete paths quickly after handover [1]. The following subsequent sections discuss QoS re-establishment mechanisms in mobile scenarios in further detail. 9.1 Fast QoS Re-establishment This section considers two possible mechanisms to quickly re-establish reservation of resources along the new path after handover: Pre-establishment and Fast re-establishment [15]. The pre-establishment approach can be used to reserve resources in areas which the MN may visit to support seamless QoS services. Although the NSIS requirement draft describes only QoS re-establishment after handover [1], the pre-establishment is a desirable feature to guarantee the seamless QoS services. On the other hand, the fast re-establishment approach can be used to quickly set up reservation of resources along the new path to minimize the disruption of QoS services after handover. To carry out the pre-establishment mechanism, NEs may interwork with seamless mobility protocols (e.g., CARD and CT) as mentioned in Section 8 and use the CCND to localize the pre-establishment. The refresh timer value may also be optimized to avoid unnecessary pre-reservation (see Appendix A for further details). If pre-establishment is not used (or if pre-establishment of the mQoS-NSLP fails due to the lack of available resources or the failure of NEs along the new path), the NEs are responsible for fast re-establishing the mQoS-NSLP state after handover. The key idea of the fast re-establishment is to transfer the mQoS-NSLP state to candidate NEs between the CCN and the CAR by the CT before handover and to localize the re-establishment after handover. With the context transfer approach described above, the candidate NEs try to distribute the information of mQoS-NSLP state among themselves or continuously maintain the state until the pre-establishment succeeds before the completion of handover. In this way, the candidate NEs can learn the mQoS-NSLP state through interactions with the seamboby protocols. For example, if the MN acts as a sender in the sender-initiated approach, the CAR may be used to establish the mQoS-NSLP state by Lee, et al. Expires April 26, 2004 [Page 13] Internet-Draft mQoS-NSLP October 2003 sending a reservation message where the 'PRE' bit is set or to transfer the context related to the mQoS-NSLP state toward the CCN during the handover. In this way, the candidate NEs between CAR and CCN can recognize the state information and check the avability of resources on the new path. It is also possible that the MN may initiate a reservation message after handover. In this case, the associated NEs can establish the mQoS-NSLP states more quickly since the mQoS-NSLP only needs to update the changed information (e.g., refresh timer value, flow ID, and so on)[17]. If the MN acts as a receiver, the CCN may also use the same process toward the CARs as the MN as a sender. If the CCN fails to transfer the states, the CRN generates a reservation message where the 'M' bit is set to establish the mQoS-NSLP state after receiving the handover information (e.g., the first BU message). In order to fast re-establish the mQoS-NSLP states in the receiver-initiated approach, a Path state may need to be established first. If the MN acts as a receiver, the mQoS-NSLP of the CCN may need to first establish the path state toward the CAR using in a peer-to-peer manner, and afterwards the MN can quickly reserve the resources by only sending a reservation message to the CRN as soon as a path setup message is received by the MN after handover. If the MN acts as a sender in the receiver-initiated approach, the CAR pre-establishes the path state up to the CCN. After handover, the mQoS-NSLP of the MN sends a path setup message where the 'M' bit is set toward the CRN but the NEs on the new path only update changed information (e.g., refresh timer value, flow ID, mQoS-NSLP states, and so on). As a result, the mQoS-NSLP state can be re-established quickly. If the CARD and the CT are not able to interwork with NTLP/mQoS-NSLP nor operate correctly, the re-establishment of the mQoS-NSLP state should be still localized to minimize the disruption of QOS services. In this case, the mQoS-NSLP states are only re-established by the same method that the existing sender-initiated and receiver-initiated approaches operate without pre-establishment after handover. In this case, mQoS-NSLP messages should be transmitted simultaneously with Handover information (e.g., the first Biding Update message in MIPv6) even if the NTLP and the mQoS-NSLP do not have any interactions with mobility protocols as described in Section 8. 9.2 Fast Release of Resources As in RSVP, reservation states may be explicitly torn down by the Lee, et al. Expires April 26, 2004 [Page 14] Internet-Draft mQoS-NSLP October 2003 mQoS-NSLP when a flow terminates or when the admission control rejects a reservation. In addition, it may be needed to release the previously reserved resources along the old path immediately after establishing the state of mQoS-NSLP along new paths due to handover. To release the previously reserved resources along the old path after handover, a CRN first needs to receive a teardown message (or a reservation message) from the MN which has arrived at a new AR. On receiving the teardown message, mQoS-NSLP of the CRN immediately updates reservation states of the old session and simultaneously transmits a reservation message toward the old AR to delete the state of the mQoS-NSLP along the old path. 9.3 Confirmation/Error Handling As in RSVP, the MN can send a request for confirmation for its reservation request. In this case, the request for confirmation is included in the resource reservation message. If any reservation fails, a reservation error message will be delivered to the MN. The reservation error message may contain enough information so that the MN can decide its future direction. If the Old AR is the last node after handover, the mQoS-NSLP of the old AR may trigger an error message that indicates that NSLP messages can not be forwarded any further. However, the states along the old path must not be deleted before establishing the state along the new path due to this error message. Lee, et al. Expires April 26, 2004 [Page 15] Internet-Draft mQoS-NSLP October 2003 10. Security Considerations The mQoS-NSLP relies on the security mechanisms described in [4]. Securing the mQoS-NSLP is provided by CMS which allows resource objects and related objects defined in this document to be encapsulated and protected by CMS. Therefore, no separate specification within the mQoS-NSLP is necessary to describe the format of these objects. This allows some flexibility in including protected objects to link the authorization step of different protocols and to transport local information within domains. The functionality described in [19] and [20] can be provided without substantial protocol modification/extensions. Lee, et al. Expires April 26, 2004 [Page 16] Internet-Draft mQoS-NSLP October 2003 11. Summary This document identified the mobility functionality of the QoS-NSLP, including make-before-break, localized path repair, state management, unidirectional and bidirectional reservation support, interactions with mobility protocols, and so on. Lee, et al. Expires April 26, 2004 [Page 17] Internet-Draft mQoS-NSLP October 2003 Appendix A. QoS Pre-establishment Procedures The pre-establishment mechanism may consist of three general operations for seamless handover [9] [10] and two main operations for QoS re-establishment: Movement Detection, Candidate Access Router Discovery (CARD), Context Transfer (CT), Candidate Crossover Node Discovery (CCND), and reservation setup. As mentioned in Section 4, a handover initiator (e.g., an MN or an AR) notifies the NE within the AR of the mobility event. In this case, the mQoS-NSLP of the NE constitutes the MOBILITY object, and should not delete the existing state along the old path even if the error message indicating the 'Can-Not-Be-Forwarded-to-the-LAST-NODE' is issued (see Section 5). After receiving the handover initiation information, the mQoS-NSLP/NTLP in the AR transfers its state information (such as the session identifier, flow identifiers, MOBILITY object, security-related information, and so on) to NSIS-aware CARs through interworking with CARD and CT as mentioned Section 8. After receiving the context, the NTLP in the candidate AR begins to trigger the CCND mechanism [21] based on the NTLP/mQoS-NSLP state information to localize pre-establishment. Before pre-establishment, the mQoS-NSLP of candidate ARs and a CCN need to reset the soft state refresh timer to the optimized value by the 'PRE' bit to utilize the resource efficiently. For example, if the refresh timer value in the pre-establishment phase is set to a little higher value than the estimated handover latency, the MN can received seamless QoS Services by the pre-reserved resources, and resources which are pre-reserved but unused will be automatically released after timeout. After handover is completed, the mQoS-NSLP should restore the original refresh timer value in order to avoid frequent transmission of refresh messages (as mentioned in Section 6). If the sender-initiated approach is used for pre-reservation and an MN acts as a sender (or a receiver), the CARs (or the CCN(s)) reserve resources in advance by sending a reservation message toward the CCN(s) (or the CARs). On the other hand, if the receiver-initiated approach is used and an MN is a sender (or receiver), the opposite operation is performed. To distinguish pre-establishment signaling messages from re-establishment signaling messages, the 'PRE' bit of the 'Refresh' object may be also used. Finally, mQoS-NSLP states between CCN and CAR will be pre-established, and the MN arriving at a new AR can receive QoS service immediately. Lee, et al. Expires April 26, 2004 [Page 18] Internet-Draft mQoS-NSLP October 2003 References [1] Brunner, M., "Requirements for Signaling Protocols", draft-ietf-nsis-req-09 (work in progress), August 2003. [2] Hancock, R., "Next Steps in Signaling: Framework", draft-ietf-nsis-fw-04 (work in progress), September 2003. [3] Chaskar, H., "Requirements of a Quality of Service (QoS) Solution for Mobile IP", RFC 3583, September 2003. [4] Schulzrinne, H., "CASP - Cross-Application Signaling Protocol", draft-schulzrinne-nsis-casp-01 (work in progress), March 2003. [5] Schulzrinne, H., "A Quality-of-Service Resource Allocation Client for CASP", draft-schulzrinne-nsis-casp-qos-01 (work in progress), March 2003. [6] McDonald, A., "A Quality of Service NSLP for NSIS", draft-mcdonald-nsis-qos-nslp-00 (work in progress), June 2003. [7] Bosch, S., "NSLP for Quality-of-Service signaling", draft-ietf-nsis-qos-nslp-00 (work in progress), September 2003. [8] Schulzrinne, H., "GIMPS: General Internet Messaging Protocol for Signaling", draft-schulzrinne-nsis-ntlp-00 (work in progress), June 2003. [9] Loughney, J., "Context Transfer Protocol", draft-ietf-seamoby-ctp-04 (work in progress), October 2003. [10] Liebsch, M., "Candidate Access Router Discovery", draft-ietf-seamoby-card-protocol-04 (work in progress), September 2003. [11] Tschofenig, H. and D. Kroeselberg, "Security Threats for NSIS", draft-ietf-nsis-threats-02 (work in progress), July 2003. [12] Buchli, M., "A Network Service Layer Protocol for QoS signaling", draft-buchli-nsis-nslp-00 (work in progress), June 2003. [13] Fu, X., "Mobility Issues in Next Steps in Signaling (NSIS)", draft-fu-nsis-mobility-01 (work in progress), October 2003. [14] Koodli, R., "Fast Handovers for Mobile IPv6", draft-ietf-mobileip-fast-mipv6-08 (work in progress), October 2003. Lee, et al. Expires April 26, 2004 [Page 19] Internet-Draft mQoS-NSLP October 2003 [15] Lee, S., "QoS Signaling for IP-based Radio Access Networks", draft-lee-nsis-signaling-ran-00 (work in progress), June 2003. [16] Braden, B., Zhang, L., Berson, S., Herzog, S. and S. Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1 Functional Specification", RFC 2205, September 1997. [17] Berger, L., Gan, D., Swallow, G., Pan, P., Tommasi, F. and S. Molendini, "RSVP Refresh Overhead Reduction Extensions", RFC 2961, April 2001. [18] Westberg, L., "A Proposal for RSVPv2", draft-westberg-proposal-for-rsvpv2-01 (work in progress), November 2002. [19] Hamer, L-N., Gage, B. and H. Shieh, "Framework for Session Set-up with Media Authorization", RFC 3521, April 2003. [20] Hamer, L-N., Gage, B., Kosinski, B. and H. Shieh, "Session Authorization Policy Element", RFC 3520, April 2003. [21] Shen, C., "Several Framework Issues Regarding NSIS and Mobility", draft-shen-nsis-mobility-fw-00 (work in progress), July 2002. [22] Chaskar, H. and C. Westphal, "QoS Signaling Framework for Mobile IP", draft-westphal-nsis-qos-mobileip-00 (work in progress), June 2002. [23] Schulzrinne, H., "GIMPS: General Internet Messaging Protocol for Signaling", draft-ietf-nsis-ntlp-00 (work in progress), October 2003. [24] Jeong, S., "Mobility Functions in the NTLP", draft-jeong-nsis-mobility-ntlp-01 (work in progress), October 2003. Authors' Addresses Sung-Hyuck Lee SAMSUNG Advanced Institute of Technology i-Networking Lab. San 14-1, Nongseo-ri, Giheung-eup Yongin-si, Gyeonggi-do 449-712 KOREA Phone: +82 31 280 9585 EMail: starsu.lee@samsung.com Lee, et al. Expires April 26, 2004 [Page 20] Internet-Draft mQoS-NSLP October 2003 Seong-Ho Jeong Hankuk University of FS 89 Wangsan Mohyun Yongin-si, Gyeonggi-do 449-791 KOREA Phone: +82 31 330 4642 EMail: shjeong@hufs.ac.kr Jongho Bang SAMSUNG Advanced Institute of Technology i-Networking Lab. San 14-1, Nongseo-ri, Giheung-eup Yongin-si, Gyeonggi-do 449-712 KOREA Phone: +82 31 280 9585 EMail: jh0278.bang@samsung.com Byoung-Joon (BJ) Lee SAMSUNG Advanced Institute of Technology i-Networking Lab. San 14-1, Nongseo-ri, Giheung-eup Yongin-si, Gyeonggi-do 449-712 KOREA Phone: +82 31 280 9626 EMail: bj33.lee@samsung.com Lee, et al. Expires April 26, 2004 [Page 21] Internet-Draft mQoS-NSLP October 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. Copies of claims of rights made available for publication 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 implementors or users of this specification can be obtained from the IETF Secretariat. 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Expires April 26, 2004 [Page 22] Internet-Draft mQoS-NSLP October 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. Lee, et al. Expires April 26, 2004 [Page 23]