Network Working Group                                     A. Mankin, Ed.
Request for Comments: 2208                                       USC/ISI
Category: Informational                                         F. Baker
                                                           Cisco Systems
                                                               B. Braden
                                                              S. Bradner
                                                               M. O`Dell
                                                      UUNET Technologies
                                                              A. Romanow
                                                        Sun Microsystems
                                                              A. Weinrib
                                                       Intel Corporation
                                                                L. Zhang
                                                          September 1997

                  Resource ReSerVation Protocol (RSVP)
                   Version 1 Applicability Statement
                     Some Guidelines on Deployment

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.


   This document describes the applicability of RSVP along with the
   Integrated Services protocols and other components of resource
   reservation and offers guidelines for deployment of resource
   reservation at this time.  This document accompanies the first
   submission of RSVP and integrated services specifications onto the
   Internet standards track.

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RFC 2208           RSVP Applicability and Deployment      September 1997

1.  Introduction

   RSVP [RFC 2205] is a unicast and multicast signalling protocol,
   designed to install and maintain reservation state information at
   each router along the path of a stream of data.  The state handled by
   RSVP is defined by services [RFC 2211] and [RFC 2212] specified by
   the Integrated Services WG.  These services and RSVP are being
   introduced to the IETF's standards track jointly.  From henceforth,
   the acronym RSVP on its own is used as a shorthand for the signalling
   protocol combined with the integrated service specifications.

   RSVP must be used in conjunction with several additional components,
   described in Table 1.

          Table 1  Additional Components of Resource Reservation

   1. Message formats in which parameters for desired services can be
      expressed. A proposed standard set of these formats is specified
      in [RFC 2210].

   2. Router and host mechanisms (e.g. packet classification and
      scheduling, admission control algorithms) to implement one or
      both of the models [RFC 2211] and [RFC 2212], which are also
      in the standards track.

   3. Message formats in which parameters for desired policies for
      admission control and resource use can be expressed.  A small
      common subset of these formats for standards track is in the
      RSVP WG's charter.  The Policy objects in the RSVP Protocol
      Specification are optional only at this time.

   4. Diversely located mechanisms implementing desired admission
      control policy functions, including authorization and other
      security mechanisms.

   In the presence of some form of each component in Table 1, RSVP-
   enabled applications can achieve differentiated qualities of service
   across IP networks.  Networked multimedia applications, many of which
   require (or will benefit from) a predictable end-user experience, are
   likely to be initial users of RSVP-signalled services.

   Because RSVP and the integrated services and other components listed
   in Table 1 mark a significant change to the service model of IP
   networks, RSVP has received considerable interest and press in
   advance of its release as a standards track RFC.  At present, many
   vendors of operating systems and routers are incorporating RSVP and
   integrated services into their products for near-future availability.
   The goal of this applicability statement is to describe those uses of

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RFC 2208           RSVP Applicability and Deployment      September 1997

   the current RSVP specification that are known to be feasible, and to
   identify areas of limitation and ongoing chartered work addressing
   some of these limitations.

2.  Issues Affecting Deployment of RSVP

   Wide scale deployment of RSVP must be approached with care, as there
   remains a number of outstanding issues that may affect the success of

2.1.  Scalability

   The resource requirements (processing and storage) for running RSVP
   on a router increase proportionally with the number of separate
   sessions (i.e., RSVP reservations).  Thus, supporting numerous small
   reservations on a high-bandwidth link may easily overly tax the
   routers and is inadvisable.  Furthermore, implementing the packet
   classification and scheduling capabilities currently used to provide
   differentiated services for reserved flows may be very difficult for
   some router products or on some of their high-speed interfaces (e.g.
   OC-3 and above).

   These scaling issues imply that it will generally not be appropriate
   to deploy RSVP on high-bandwidth backbones at the present time.
   Looking forward, the operators of such backbones will probably not
   choose to naively implement RSVP for each separate stream.  Rather,
   techniques are being developed that will, at the "edge" of the
   backbone, aggregate together the streams that require special
   treatment.  Within the backbone, various less costly approaches would
   then be used to set aside resources for the aggregate as a whole, as
   a way of meeting end-to-end requirements of individual flows.

   In the near term, various vendors are likely to use diverse
   approaches to the aggregation of reservations.  There is not
   currently chartered work in the IETF for development of standards in
   this space. A BOF, Future Directions of Differential Services, on
   April 7, 1997, at the Memphis IETF, is to consider the IETF's next
   steps on this, among other issues.  Public documentation of
   aggregation techniques and experience is encouraged.

2.2.  Security Considerations

   The RSVP WG submission for Proposed Standard includes two security-
   related documents [Baker96, RFC 2207]. [Baker96] addresses denial and
   hijacking or theft of service attacks.  [RFC 2207] addresses RSVP
   mechanisms for data flows that themselves use IPSEC.

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RFC 2208           RSVP Applicability and Deployment      September 1997

   The first document is proposed to protect against spoofed reservation
   requests arriving at RSVP routers; such requests might be used to
   obtain service to unauthorized parties or to lock up network
   resources in a denial of service attack.  Modified and spoofed
   reservation requests are detected by use of hop-by-hop MD5 checksums
   (in an Integrity Object) between RSVP neighbor routers.  As
   described, RSVP hop-by-hop authentication assumes that key management
   and distribution for routers is resolved and deployed.  Until an
   effective key infrastructure is in place, manually keyed session
   integrity might be used.  In addition, [Baker96] may be updated with
   RFC 2085.

   That RSVP needs an effective key infrastructure among routers is not
   unique to RSVP: it is widely acknowledged that there are numerous
   denial of service attacks on the routing infrastructure (quite
   independent of RSVP) that will only be resolved by deployment of a
   key infrastructure.

   Theft of service risks will require the user to deploy with caution.
   An elementary precaution is to configure management logging of new
   and changed filter specifications in RSVP-enabled infrastructure,
   e.g. the newFlow trap [RFC 2206].

   The Integrity object defined by [Baker96] may also play a role in
   policy control, as will be described in 2.3.

   The second security-related document provides a mechanism for
   carrying flows in which the transport and user octets have been
   encrypted (RFC 1827).  Although such encryption is highly beneficial
   to certain applications, it is not relevant to the functional
   security of RSVP or reservations.

   The following section on Policy Control includes additional
   discussion of RSVP authorization security.

2.3.  Policy Control

   Policy control addresses the issue of who can, or cannot, make
   reservations once a reservation protocol can be used to set up
   unequal services.

   Currently, the RSVP specification defines a mechanism for
   transporting policy information along with reservations.  However,
   the specification does not define policies themselves.  At present,
   vendors have stated that they will use the RSVP-defined mechanism to
   implement proprietary policies.

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RFC 2208           RSVP Applicability and Deployment      September 1997

   The RSVP WG is chartered to specify a simple standardized policy
   object and complete simple mechanisms for session use of the
   Integrity object in the near future.  This applicability statement
   may be updated at the completion of the WG's charter.

   Before any decision to deploy RSVP, it would be wise to ensure that
   the policy control available from a vendor is adequate for the
   intended usage.  In addition to the lack of documented policy
   mechanisms in any of the policy areas (such as access control,
   authorization, and accounting), the community has little experience
   with describing, setting and controlling policies that limit Internet
   service.  Therefore it is likely that vendor solutions will be
   revised often, particularly before the IETF has developed any policy

3.  Recommendations

   Given the current form of the RSVP specifications, multimedia
   applications to be run within an intranet are likely to be the first
   to benefit from RSVP.  SNA/DLSW is another "application" considered
   likely to benefit.  Within the single or small number of related
   administrative domains of an intranet, scalability, security and
   access policy will be more manageable than in the global Internet,
   and risk will be more controllable.  Use of RSVP and supporting
   components for small numbers of flows within a single Internet
   Service Provider is similar to an intranet use.

   Current experience with RSVP has been collected only from test runs
   in limited testbeds and intranet deployment.  We recommend that
   people begin to use RSVP in production intranet or limited ISP
   environments (as mentioned above), in which benefits can be realized
   without having to resolve some of the issues described in Section 2.
   To quote RFC 2026 about the use of Proposed Standard technology:

     Implementors should treat Proposed Standards as immature
     specifications.  It is desirable to implement them in order to gain
     experience and to validate, test, and clarify the specification.
     However, since the content of Proposed Standards may be changed if
     problems are found or better solutions are identified, deploying
     implementations of such standards into a disruption-sensitive
     environment is not recommended.

   General issues of scalability, security and policy control as
   outlined in Section 2 are the subjects of active research and
   development, as are a number of topics beyond this applicability
   statement, such as third-party setup of either reservations or
   differentiated service.

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4.  References

   [Baker96]  Baker, F., "RSVP Cryptographic Authentication", Work in

   [RFC 2206], Baker, F. and J. Krawczyk, "RSVP Management Information
           Base", RFC 2206, September 1997.

   [RFC 2207]  Berger, L. and T. O'Malley, "RSVP Extensions for IPSEC
           Data Flows", RFC 2207, September 1997.

   [RFC 2211] Wroclawski, J., "Specification of Controlled-Load
           Network Element Service", RFC 2211, September 1997.

   [RFC 2212] Shenker, S., C. Partridge and R. Guerin, "Specification
           of Guaranteed Quality of Service", RFC 2212, September 1997.

   [RFC 2205]  Braden, R. Ed. et al, "Resource ReserVation Protocol
           -- Version 1 Functional Specification", RFC 2205,
           September 1997.

   [RFC 2210] Wroclawski, J., "The Use of RSVP with IETF Integrated
           Services", RFC 2210, September 1997.

5.  Authors' Addresses

   Fred Baker                    Abel Weinrib
   Cisco Systems                 Intel Corporation
   Phone: 408-526-4257           Phone: 503-264-8972
   EMail:         EMail:

   Bob Braden
   USC/ISI                       Lixia Zhang
   4676 Admiralty Way            UCLA Computer Science Department
   Marina Del Rey, CA 90292      4531G Boelter Hall
   Phone: 310-822-1511           Los Angeles, CA 90095-1596 USA
   EMail:         Phone: 310-825-2695

   Scott Bradner                 Allyn Romanow
   Harvard University            Sun Microsystems
   Phone: 617-495-3864           Phone: 415-786-5179
   EMail:        EMail:

   Michael O'Dell                Allison Mankin
   UUNET Technologies  
   Phone: 703-206-5471

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