Internet Engineering Task Force J. Manner Internet-Draft T. Suihko Expires: July, 2003 M. Kojo M. Liljeberg K. Raatikainen January, 2003 Localized RSVP Status of this Memo This document is a submission to the NSIS Working Group of the Internet Engineering Task Force (IETF). Comments should be submitted to the nsis@ietf.org mailing list. Distribution of this memo is unlimited. 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 in July 2003. Copyright Notice Copyright (C) The Internet Society (2000). All Rights Reserved. Abstract Guaranteed QoS for multimedia applications is based on reserved resources in each node on the end-to-end path. Even if the correspondent node does not support QoS, it would be useful to be able to reserve at least local resources at the access network, especially wireless link resources. Additionally, for mobile nodes the continuity of QoS is disturbed due to end-to-end signalling or slow re-reservations of resources after each handover. This draft proposes a simple enhancement to RSVP, so that initial resource reservations and re-reservations due to host mobility can be done locally in an access network. Manner et al Expires July 2003 [Page 1] Internet-Draft Localized RSVP January 2003 Table of Contents 1 Introduction ................................................. 2 1.1 Related work ............................................... 3 2 Local QoS Support ............................................ 4 2.1 Upstream transfers ......................................... 5 2.2 Downstream transfers ....................................... 5 2.3 Additional functionality ................................... 6 2.4 Addressing Issues .......................................... 8 2.5 Interworking Issues ........................................ 8 3 Fast local repair for mobile nodes ........................... 10 4 Security Consideration ....................................... 12 5 IANA Considerations .......................................... 13 6 Summary ...................................................... 13 7 References ................................................... 14 8 Author's Addresses ........................................... 15 1. Introduction Future mobile access networks will be based on IP technology. This implies that, on the network layer, all traffic, both traditional data and streamed data like audio or video, is transmitted as packets. Increasingly popular multimedia applications would benefit from better than best-effort service from the network, a forwarding service with strict Quality of Service (QoS) with guaranteed minimum bandwidth and maximum delay. Other applications, such as electronic commerce, network control and management, and remote login applications, would also benefit from a differentiated treatment. The IETF has two main models for providing differentiated treatment of packets in routers. The Integrated Services (IntServ) model [1] together with the Resource Reservation Protocol (RSVP) [2] [3] provides per-flow guaranteed end-to-end transmission service. The Differentiated Services (DiffServ) framework [4] provides non- signalled flow differentiation that usually provides, but does not guarantee, proper transmission service. These architectures, however, have problems. For example, RSVP requires support from both communication end points and from the intermediate routers. DiffServ, on the other hand, requires support from the sender of a stream and from the network nodes. The Internet Architecture Board has outlined additional issues related to these two architectures [5]. Let's consider a scenario, where a fixed network correspondent node (CN) would be sending a multimedia stream to an end host behind a wireless link. If the correspondent node does not support RSVP it cannot signal its traffic characteristics to the network and request specific forwarding services. Likewise, if the correspondent node is not able to mark its traffic with a DiffServ Code Point (DSCP) to trigger service differentiation, the multimedia stream will get only best-effort service which may result in poor visual and audio quality in the receiving application. Even if the connecting wired network is over-provisioned, reserving local resources is especially important in wireless access networks, where the bottleneck resource is most Manner et al Expires July 2003 [Page 2] Internet-Draft Localized RSVP January 2003 probably the wireless link. In the absence of end-to-end QoS support, an end-host could still want to reserve resources from the local (edge) network, for example from its access network, for both outgoing and incoming traffic. We propose a slight modification to RSVP that allows distinguishing local network reservations from the end-to-end reservations. The end host does not need to know the access network topology or the nodes that will reserve the local resources. The reservation message itself identifies the intention and the access network will find the correct network node(s) to respond to the reservation. Note that the scheme is not tied to only mobile networks but can be used in any access network that needs flexible local resource allocations. The localized RSVP signalling would fit well, for example, with a SIP session, where a call set up can have a pre-condition: if the request for local resources is successful, the end-host can send the COMET message and make the call "ring" [SIP]. Both ends would use their own local reservations. All mobility-related terminology in this document are taken from [16]. Therefore, the commonly used term 'access router' (AR) means the 'default router'. 1.1. Related work Currently we can identify two ways to signal QoS requirements to an access network: DiffServ Code Points (DSCP) and RSVP with IntServ. In the DiffServ-based solution an end host can mark the upstream packets with proper DSCP values, but for the downstream the gateway on the edge of the access network must be able to identify and handle the preferred streams. This can be accomplished with default values for different micro flows in the Service Level Agreement negotiated between the client and the access network service provider. An alternative way to make use of DiffServ could be through a Bandwidth Broker [6] [7] [8] that dynamically returns the proper code point for each flow: when the first packet of a flow arrives at the access network edge router, it requests the proper code point from the Bandwidth Broker. The router maintains a mapping from micro flow identification to the DiffServ code point (soft state) so that future packets can be directly identified and labelled. Still, this would require a protocol that the end host could use to dynamically adjust the mapping information stored at the access network edge for the incoming traffic. RSVP can provide the signalling mechanism for QoS requirements to the access network. For upstream reservations, the end host would send the Path message to the access network edge router, which would return the Resv message and set up the reservations. The edge router would act as an RSVP proxy [9]. However, the reservation in the downlink direction is not as straightforward since the downlink reservation needs to be initiated by the RSVP proxy. We would need a Manner et al Expires July 2003 [Page 3] Internet-Draft Localized RSVP January 2003 way to trigger the proxy to initiate the RSVP signalling for a downlink flow. Thus, these mechanisms do not seem to solve the problem entirely. The DiffServ mechanisms cannot provide explicit resource reservations. The problem with the RSVP proxy approach is that the proxy cannot automatically distinguish reservations that would be answered by the correspondent node and reservations that would require interception. Additionally, the RSVP proxy needs a way to know when to allocate resources for incoming flows. Mobile access networks also add to the problems, since mobile nodes can frequently change their point of attachment in the network and resource allocations need to be re- arranged, including changing the serving RSVP proxy. 2. Local QoS Support Our solution to the problem of localized QoS co-ordination is based on proxies and the RSVP local repair mechanism [2]. The proxy is running on an RSVP node and is called the Localized RSVP Proxy server (LRSVP proxy). The first sketch of this solution appeared in [10] and [11], although some implementation ideas have changed since. To implement a local resource signalling, we first of all need two flag bits from the unused Flags field in the RSVP Session Object. The Local Indication (LI) bit (currently we use bit 0x8) is used to differentiate reservations that are internal to the access network - when the bit is set the RSVP message is part of local resource signalling. A default value of zero indicates standard end-to-end signalling. The Expedited Refresh (ER) bit (currently we use bit 0x4) is used to indicate that a Path message is sent as a refresh to a broken path and must be forwarded immediately. This indication is needed because each RSVP hop propagates a Path message before a timeout only if the Path state has changed - when a route changes at the receiver end of the data flow, a Path message is needed to set up again the Path state. This is discussed in more detail later. We also need two new message types called "Path Request" message with an initial message type number 8 and "Path Request Tear" with an initial message type number 9. The first message is used to request a Path message from the access network LRSVP proxy and the second message is used to tear down a downstream reservation. Note that due to the new message types, all RSVP routers inside the access network must be upgraded with the LRSVP extension. When a local end host wants to reserve resources in the local access network, it uses the LI flag in RSVP messages to indicate a local reservation. The structure of the RSVP messages follows the RSVP standard. The LRSVP proxy that receives an RSVP message with the LI bit set will notice that the flag was set, does not forward the message further to the next hop and responds according to the following description. Manner et al Expires July 2003 [Page 4] Internet-Draft Localized RSVP January 2003 2.1. Upstream transfers Setting upstream reservations is straightforward and follows closely the standard RSVP functionality. The local end host sends the usual Path message, but sets the LI flag bit in the Session Object. The Session Object of the message defines the destination of the flow that will eventually be transmitted from the local end host, and the Sender Template provides information about the local end host itself. [END HOST] [Access Router] [X-OVER ROUTER] [PROXY] [CN] | | | | | |------------- Path towards CN (LI) ---------->| | | | | | | | | | (proxy intercepts) | | | | | | | | |<---- Resv ----| | | |<---- Resv ----| | | |<---- Resv ---| | | | | | | | | Figure 1: Local Upstream reservation The Path message is routed within the access network and sets the Path state in RSVP routers. When the LRSVP proxy receives the Path message, it notes due to the LI bit that the reservation is meant to stay within the access network and responds with a Resv message. It will not forward the Path message further to the next hop. When a Resv message arrives at the local end host, the resources for the session defined in the Path message have been allocated. 2.2. Downstream transfers Before setting a downstream resource reservation, the local end host needs to be aware of the data senders. For multimedia communications, a session is usually initiated with application layer protocols like SIP [15] or RTSP [12]. Based on this correspondence, the local end host knows the necessary information about the sender. Another, more coarse reservation could be set, for example, for browsing different audio servers; the local end host would indicate in the RSVP messages that the sender will use UDP. It is, therefore, possible to make resource reservations for any sender that wants to communicate with the local end host. However, in order to allow for more accurate QoS support, more information should be given. The way to find this information is out of scope of this document. In order to set up the downstream reservation we need a way to signal the LRSVP proxy to initiate the RSVP reservation set up on behalf of the sender(s), that is, to send a Path message. To achieve this, the local end host sends the Path Request message with the LI flag bit set (Fig. 2). The Path Request message is identical to a standard Path message apart from the message type field. The Session Object must include information about the recipient, the local end host in this case, and the Sender Template must define the expected Manner et al Expires July 2003 [Page 5] Internet-Draft Localized RSVP January 2003 sender(s). The Traffic specification (TSpec) can either be based on the local end user's wishes, a best estimate of the incoming traffic characteristics, or on application level session signalling prior to the transfer. [END HOST] [Access Router] [X-OVER ROUTER] [PROXY] [CN] | | | | | |------------ Path Request towards CN (LI) --->| | | | | | | | | | (proxy intercepts) | | | | | | | | |<- Path (LI) --| | | |<- Path (LI) --| | | |<- Path (LI) -| | | | | | | | | |- Resv (LI) ->| | | | | |-- Resv (LI) ->| | | | | |-- Resv (LI) ->| | | | | | | Figure 2: Local downstream reservation When the LRSVP proxy receives this message, it detects that the message is meant to stay within the access network. The message type indicates that the proxy should initiate an RSVP reservation for a downstream flow and use the information in the message to fill the objects in a Path message. The proxy now generates a Path message that includes the parameter values in the Path Request message and sends it towards the local end host. When the local end host receives the Path message, it responds with a Resv message with the LI flag set. This reserves the downstream resources within the access network for the senders originally identified by the local end host. The Path Request message could also be used end-to-end, to request the correspondent node to initiate a resource reservation. In this case, the LI bit must not be set, since it would stop the message at the local access network. 2.3. Additional functionality All the other features of RSVP are used with LRSVP in the standard way including the local repair mechanism and reservation tear down. Downstream reservations are torn down with the Path Request Tear message. The operation follows that of the Path Request: the message does not change states within the network, but only triggers the proxy to send a Path Tear message towards the end host for the specified session. All messages used for local reservations must have the LI flag set in order to keep the signalling within the access network. Intermediate RSVP routers between the local end host and the LRSVP proxy should Manner et al Expires July 2003 [Page 6] Internet-Draft Localized RSVP January 2003 not process the Path Request message and they should forward it as an ordinary IP packet. An enhancement to the local repair changes this operation and is discussed later. The proposed scheme also allows RSVP to be used to signal DiffServ Code Points in a DiffServ access network using the RSVP DCLASS object [13]. The DCLASS object is used to represent and carry DiffServ code points within RSVP messages. The local end host can use the DCLASS object to instruct the LRSVP proxy to mark incoming traffic with certain DiffServ code points to trigger different forwarding behavior within the DiffServ access network. The local end host, however, needs to be aware of the different code point values and the related services, especially if other than standardized code points are used. This information can be part of host auto-configuration, for example. In addition, the LRSVP proxy may need information on how to map RSVP requests to proper DiffServ classes if it wants to have closer control of downstream resource allocations. This can be accomplished by using standardized code point values for the DiffServ Assured Forwarding service. Thus, our signalling mechanism can also be used to give relative priority to specific flows without explicit resource reservations. Furthermore, the proposed signalling can be used at both ends of a data stream. For example, if the two end hosts in different access networks are communicating with each other, both of them could use the mechanism to allocate resources, for example on their own access networks, independently of each other. This could happen, if the two access networks had a different view of QoS, one uses only IntServ and RSVP, while the other also uses DiffServ. In such a scenario, however, it may be more practical to use RSVP end-to-end, even if the core network connecting the two access networks does not support RSVP. If the reserved bits in the RSVP Session Object are deemed too valuable to be used for this kind of signalling, the RSVP CAP-object [14] could be used to carry the two bits needed by the localized RSVP. The CAP object can be used in the RSVP Path message to convey end host/upstream node capabilities to the downstream network/nodes. This would, however, add another eight bytes of headers in order to carry two bits of information. In addition, the processing of the messages is more time consuming due to the extra header. In any case, the new Path Request and Path Request Tear messages are still needed, because it would complicate the message processing in routers if the "request to send a Path" was indicated as another bit in the CAP object. With the new message type intermediate routers on the uplink can forward these two messages to the LRSVP proxy faster, since the router does not need to examine the whole packet and the CAP object in order to find the same information, just the message type. Manner et al Expires July 2003 [Page 7] Internet-Draft Localized RSVP January 2003 2.4. Addressing Issues When the local end host sends Path or Path Request messages, it needs to use some IP address as the destination in the IP header. The first option is to use the destination address of the correspondent host our local end host is trying to initiate a reservation for. However, the end host may not know the correspondent node address, for example, if it wants to allocate resources only for certain services regardless of the sender, HTTP, for example. In such a case, the end host must be given an address of an LRSVP proxy through auto- configuration. Alternatively, in an IPv6 access network, LRSVP proxies could have a reserved anycast address. A further concern arises if the access network has several inbound routes. It is possible that the local downstream reservation initiated by the end host is set on a wrong LRSVP proxy, one that will not get the packets arriving to the end host. This seems more of a network design issue and therefore the access network operator must locate the LRSVP proxies based on the packet routing - the proxies could even be co-located at the access routers. Still, it is possible to make the RSVP daemon running on the access router to multicast the messages from the local end host to all LRSVP proxies in the network and, thus, set up reservation states for all inbound routes. This could be done only when the LI bit is set and the reservation does not define a specific correspondent node. 2.5. Interworking Issues The Localized RSVP makes use of two bits in the Session Object and adds two new message types. There can be situations where such a currently non-standard message arrives at a standard RSVP router. According to the message processing rules in RFC2209, the Path Request and Path Request Tear messages would be forwarded intact by standard RSVP routers. However, for standard RSVP message, the bits used by LRSVP may or may not be kept between RSVP hops, and, thus, the indication of local signalling or the need for an expedited refresh may be lost. Therefore, all RSVP routers within an access network wanting to support local reservations must be set to keep the bits intact. In one scenario, the local network of the end host would not understand the LRSVP extension or even standard RSVP. Thus, Path messages with the LI bit and Path Request message can be routed out of the local network. If the local network of the correspondent node has support for LRSVP, that LRSVP proxy gets the Path or Path Request message with the LI bit set from the external network. The proxy must drop the message and respond with a Perr message and use a new error code called "LRSVP not supported". This would inform the host that LRSVP is not supported and it still can try end-to-end signalling. Another interesting scenario arrises when the correspondent node is a Manner et al Expires July 2003 [Page 8] Internet-Draft Localized RSVP January 2003 mobile node and the parties use route optimization. It can happen, that the correspondent node is actually in the same access network as the end host using LRSVP, and the mobile none or both nodes try to reserve local resources indepdently of each other. Now it is possible that Path and Path Request messages with the LI bit set are routed directly to the correspondent node, without going through a local network LRSVP proxy. A solution would be that end hosts can also perform the same functions as an LRSVP proxy, that is, answer to Path messages with the LI bit set and, most importantly, handle Path Request messages as well: o If an end host receives an unsolicited Path message with the LI bit set, it should respond with a Resv message and not set the LI bit. The reason is that that if the LRSVP proxies drop Path messages with the LI bit set coming from external networks, the local end hosts can trust that if they receive such a message, it must have (if the network is properly configured) arrived from a node in the local access network. Now, if our end host that sent the Path message receives the Resv without the LI bit, it can use this as an indication that the correspondent node is in the local access network and may remove the LI bit in subsequent messages belonging to the same session. o Similary, if the correspondent node receives a Path Request message, it should respond with a Path message that does not have the LI bit set. Again, if our end host receives a Path message without the LI bit set in response to the local Path Request sent earlier, it can use this as an indication that the correspondent node is in the local domain and it may remove the LI bit in subsequent messages belonging to the same session. Now, if the correspondent node moves again and changes access networks, the signalling is already set to standard end-to-end mode and reservations in the new RSVP-aware access network would be set in place. In the latter scenario, it is quite possible, that the mobile correspondent node, located in the same access network as our end host, is not (L)RSVP aware. Thus, it cannot respond the RSVP messages and local, actually, any kind of RSVP-based, reservations are not possible. A further issue concerns the interactions between local and end-to- end reservations: could a local reservation be 'upgraded' into an end-to-end reservation? This should be possible for both directions: o If the proxy receives a fully standard Path message from the local network with the same session information as an existing local reservation, it must forward the message as usual, but set a pending Path state indication for the end-to-end reservation. If a Resv arrives from the external network for this same session, it must change the reservation to an end-to-end reservation. Manner et al Expires July 2003 [Page 9] Internet-Draft Localized RSVP January 2003 o If the proxy receives a Path Request message from the local network without the LI bit set, it must forward the message to the IP destination address. If the proxy receives later a Path message from the external network for an existing local session, it must set a pending state for the end-to-end reservation. If a Resv is received from the local end host without the LI bit set, the proxy must change its state for the session to 'end-to-end' (by removing a local- indication from its session structures) and forward the Resv message further to the external network. Thus, it would be possible to upgrade a local session to end-to-end status. It is not clear whether there is a need for an end-to-end session to be 'downgraded' into a local session. 3. Fast local repair for mobile nodes The RSVP standard [2] defines that Path messages can perform a local repair of reservation paths. When the route between the communicating end hosts changes, a Path message will set the Path state of the reservation on the new route and a subsequent Resv message will make the resource reservation. Therefore, by sending a Resv message a host cannot alone update the reservation, and thus perform a local repair, before a Path message has passed. The RSVP specification also says that in order to provide fast adaptation to routing changes without the overhead of short refresh periods, the local routing protocol module can notify the RSVP process of route changes for particular destinations. The RSVP process should use this information to trigger a quick refresh of state for these destinations, using the new route (Chapter 3.6, RFC2205 [2]). However, for example, Mobile IP, does not affect routing directly in routers, and thus mobility may not be noticed at intermediate RSVP routers. When the mobile node has moved, it can send a Path message for each upstream resource reservation and initiate the local repair mechanism (Fig. 3). However, for the downstream, the mobile node will need to wait until it receives a Path message, settting up the Path state on the new route. Only after receiving the Path message, the mobile can send a Resv message to re-reserve the downstream resources. [END HOST] [NEW AR] [X-OVER ROUTER] [RSVP ROUTER] [PROXY] | | | | | |-- Path towards CN (LI)---->| | | | | | | | | | (X-over router intercepts) | | | | | | | | |<- Resv (LI) -| | | |<- Resv (LI)-| | | | | | | | | Figure 3: Fast upstream reservation The Path Request message can be used in mobile networks to initiate a faster local repair of downstream reservations on behalf of a mobile Manner et al Expires July 2003 [Page 10] Internet-Draft Localized RSVP January 2003 node that changed access routers during an ongoing RSVP session. When the mobile node changes its access router in the network, it should send the Path Request message immediately after the handover (Fig 4). The message must have the ER bit set to indicate that the request is for an existing session and triggered due to movement. The Path Request message is forwarded through the intermediate RSVP routers until it arrives at the LRSVP proxy. The message would then instruct the proxy to initiate a local repair by sending the needed Path message. The proxy must set the ER bit in the Session Object to indicate that this Path message is not an ordinary refresh message but instead triggered by a routing change and therefore must be forwarded immediately to the next hop. If the ER bit is not set, the RSVP router in Fig. 4 would not forward the Path message immediately towards the mobile node but, instead, would wait until its own scheduled refresh timeout. [END HOST] [NEW AR] [X-OVER ROUTER] [RSVP ROUTER] [PROXY] | | | | | |-------------- Path Request towards CN (LI,ER) --------------->| | | | | | | | | |<-Path (LI,ER)-| | | |<-Path (LI,ER)-| | | |<-Path (LI,ER)-| | | |<-Path (LI,ER)-| | | | | | | | | |- Resv (LI) -->| | | | | |- Resv (LI) -->| | | | | | | | Figure 4: Fast downstream reservation If the movement of the mobile node results in packets to flow through a new LRSVP proxy, the Path Request message would re-reserve the local resources for the new path. In this case, the proxy notes that the ER bit is set, but, since there is no existing state, it will initiate a new reservation. The ER bit must not be set in the following Path message since the reservation is a new one for this route. A enhancement to the scheme would allow a cross-over RSVP router that has the reservation for the mobile node stored on a different interface to send the needed Path message (Fig. 5). RSVP routers inside the access network would look into Path Request messages. If the router notices it is the cross-over router, it sends a Path message towards the local end host. If an RSVP router sends the Path message, it must not send the Path Request message any further. This requires more intelligence from intermediate RSVP routers, but allows for faster state updates. This functionality would be especially important when the session is end-to-end instead of local: the Path Request message would not go to the correspondent node, but trigger the closer cross-over router to repair the local path of the reservation. Manner et al Expires July 2003 [Page 11] Internet-Draft Localized RSVP January 2003 [END HOST] [NEW AR] [X-OVER ROUTER] [PROXY] | | | | |- Path Request towards CN (LI,ER) ->| | | | | | | | (X-over router intercepts) | | | | | | |<--- Path (LI) ---| | |<-- Path (LI) ---| | | | | | | |--- Resv (LI) -->| | | | |--- Resv (LI) --->| | | | | | Figure 5: Enhancement of the fast downstream reservation The LI flag must be set in all RSVP refresh messages if the reservation is set for the local access network. This will prevent refresh message, like the Path Request message, to be routed out of the access network. 4. Security Consideration The Path Request message is handled similarly to a Reservation Confirmation. Thus, the message triggers most processing at the LRSVP proxy. This could potentially be used for Denial of Service attacks. A possible solution is to make RSVP daemons located on access routers make a sanity check on all Path Request (and Path Request Tear) messages: the receiver of the stream must be a node on a link connected to the AR. This requires that a security association must be set up between the local end hosts and the access routers. This has the benefit that the proxy may trust that the access router has authenticated and authorized the message; this can be seen as distributed processing (of the authentication and authorization data). The same considerations apply for the Path message. The RSVP daemon at the end hosts and LRSVP proxy must also modify their security/sanity checks to allow the end host to send the Path Request with apparently suspicious session information (identifying the correspondent node(s)). Also, the proxy must be able to send RSVP messages "on-behalf" of external network nodes. The LRSVP proxy must be configured to identify its ingress and egress interfaces. If the proxy receives a Path or a Path Request message with the LI bit set from outside the access network, it must drop the message. The two new messages can make use of the standard RSVP INTEGRITY and POLICY objects. For the remaining functionality, the security considerations with standard RSVP apply. Manner et al Expires July 2003 [Page 12] Internet-Draft Localized RSVP January 2003 5. IANA Considerations IANA needs to allocate the two flag bits in the RSVP Session Object, the LI and ER bits. In addition, IANA needs to give two RSVP message type numbers to the Path Request and Path Request Tear messages and one Error Type indicating that a local resource reservation is not allowed. 6. Summary In summary, the Localized RSVP requires the following changes in the standard RSVP protocol: a) A new message type and number, named Path Request (initially number 8). b) A new message type and number, named Path Request Tear (initially number 9). c) A bit from the Session Object for the use as the Local Indication (LI) (initially bit 0x8). d) A bit from the Session Object for use as the Expedited Refresh (ER) indication (initially bit 0x4). e) An RSVP router must keep the LI bit set in all messages belonging to that session, if it encounters packets with the bit set. f) An RSVP router that is not also a proxy, must forward an RSVP packet with a message type "Path Request" without storing state. g) An access network RSVP router should be able to use the Path Request as an indication of the need for a local repair. This can enable faster reservation set up following a handover. This affects point f), because the router that receives a Path Request must first check if it has the Path state stored on another network interface. If one is present, the Path Request message must not be forwarded to the next hop and instead the router must send a Path message towards the mobile node. h) A new error code to indicate that the access network does not support local reservations. If local resources cannot be requested, the end-host can always try to do end-to-end signalling. To summarize, these changes are small and would make RSVP more appealing as a signalling protocol for IP access networks. The changes are required only within access networks, unless the Path Request message is deemed useful for a wider application. Manner et al Expires July 2003 [Page 13] Internet-Draft Localized RSVP January 2003 7. References [1] R. Braden, D. Clark, S. Shenker, "Integrated Services in the Internet Architecture: an Overview". Internet Engineering Task Force, Request for Comments 1633, June 1994. [2] R. Braden, L. Zhang, S. Berson, S. Herzog, S. Jamin. "Resource ReSerVation Protocol (RSVP), Version 1 Functional Specification. Internet Engineering Task Force, Request for Comments 2205, September, 1997. [3] J. Wroclawski, "The Use of RSVP with IETF Integrated Services. Internet Engineering Task Force, Request for Comments 2210, September, 1997. [4] S. Blake, D. Black, M. Carlson, E. Davies, Z. Wang, W. Weiss, "An Architecture for Differentiated Services", Internet Engineering Task Force, Request for Comments 2475, December, 1998. [5] G. Huston, "Next Steps for the IP QoS Architecture". Internet Engineering Task Force, Request for Comments 2990, November 2000. [6] K. Nichols, V. Jacobson, L. Zhang, "A Two-bit Differentiated Services Architecture for the Internet". Internet Engineering Task Force, Request for Comments 2638, July 1999. [7] R. Yavatkar, D. Hoffman, Y. Bernet, F. Baker, M. Speer, "SBM (Subnet Bandwidth Manager): A Protocol for RSVP-based Admission Control over IEEE 802-style networks". Internet Engineering Task Force, Request for Comments 2814, May 2000. [8] Phil Chimento and Ben Teitelbaum, "QBone Bandwidth Broker Architecture". The Internet2 initiative, June 2000. (http://qbone.internet2.edu/bb/bboutline2.html). [9] S. Gai, D. G. Dutt, N. Elfassy, Y. Bernet, "RSVP Proxy". Internet Draft (work in progress), March 2002 (expired) (draft-ietf-rsvp- proxy-03.txt). [10] Jukka Manner and Kimmo Raatikainen, "Extended Quality-of-Service for Mobile Networks". Proceedings of the 9th International Workshop on Quality of Service (IWQoS), June 2001, pp. 275-280. Published in the series Springer Lecture Notes in Computer Science (LNCS) 2092. [11] IST-BRAIN Project, "Deliverable D2.2: BRAIN architecture specifications and models, BRAIN functionality and protocol specification". March 2001, (available at: http://www.ist- brain.org). [12] H. Schulzrinne, A. Rao, R. Lanphier, "Real Time Streaming Protocol (RTSP)". Internet Engineering Task Force, Request for Comments 2326, April 1998. [13] Y. Bernet,"Format of the RSVP DCLASS Object". Internet Manner et al Expires July 2003 [Page 14] Internet-Draft Localized RSVP January 2003 Engineering Task Force, Request for Comments 2996, November 2000. [14] Hamid Sued, "Capability Negotiation: The RSVP CAP Object". Internet Draft (work in progress), May 2001 (expired) (draft-ietf- issll-rsvp-cap-03.txt). [15] J. Rosenberg aet al., "SIP: Session Initiation Protocol". RFC 3261, June 2002 [16] J. Manner at al., "Mobility related terminology". Internet Draft, November 2002 (draft-ietf-seamoby-mobility- terminology-01.txt). 8. Author's Addresses Questions about this document may be directed to: Jukka Manner Department of Computer Science University of Helsinki P.O. Box 26 (Teollisuuskatu 23) FIN-00014 HELSINKI Finland Voice: +358-9-191-44210 Fax: +358-9-191-44441 E-Mail: jmanner@cs.helsinki.fi Markku Kojo Department of Computer Science University of Helsinki P.O. Box 26 (Teollisuuskatu 23) FIN-00014 HELSINKI Finland Voice: +358-9-191-44179 Fax: +358-9-191-44441 E-Mail: kojo@cs.helsinki.fi Kimmo Raatikainen Department of Computer Science University of Helsinki P.O. Box 26 (Teollisuuskatu 23) FIN-00014 HELSINKI Finland Voice: +358-50-483-6275 Fax: +358-9-191-44441 E-Mail: kraatika@cs.helsinki.fi Tapio Suihko VTT Information Technology Manner et al Expires July 2003 [Page 15] Internet-Draft Localized RSVP January 2003 P.O. Box 1203 FIN-02044 VTT Finland Voice: +358-9-456-6078 Fax: +358-9-456-7028 E-Mail: tapio.suihko@vtt.fi Mika Liljeberg Nokia Research Center P.O. Box 407 FIN-00045 Nokia Group Finland Voice: +358-50-4836791 Fax: +358- E-Mail: Mika.Liljeberg@nokia.com Acknowledgement This work has been partially performed in the framework of the IST project IST-2000-28584 MIND, which is partly funded by the European Union. The authors would like to acknowledge the help of their colleagues in preparing this document, in particular Eleanor Hepworth and Alberto Lopez. Full Copyright Statement Copyright (C) The Internet Society (2000). 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 assigns. 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 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Manner et al Expires July 2003 [Page 16]