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Internet Engineering Task Force                                J. Manner
Internet-Draft                                                 T. Suihko
Expires: July, 2003                                              M. Kojo
                                                            M. Liljeberg
                                                          K. Raatikainen
                                                           January, 2003

                             Localized RSVP
                      <draft-manner-lrsvp-01.txt>

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,
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   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.

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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

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   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

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   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.

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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

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   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

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   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.





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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

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   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.

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   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

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   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.



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   [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.





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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.






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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

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   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

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   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.

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