RFC 2747 (rfc2747) - Page 3 of 21

RSVP Cryptographic Authentication

RFC 2747           RSVP Cryptographic Authentication       January 2000


   The security associations in IPSEC are based on destination address.
   It is not clear that RSVP messages are well defined for either source
   or destination based security associations, as a router must forward
   PATH and PATH TEAR messages using the same source address as the
   sender listed in the SENDER TEMPLATE.  RSVP traffic may otherwise not
   follow exactly the same path as data traffic.  Using either source or
   destination based associations would require opening a new security
   association among the routers for which a reservation traverses.

   In addition, it was noted that neighbor relationships between RSVP
   systems are not limited to those that face one another across a
   communication channel.  RSVP relationships across non-RSVP clouds,
   such as those described in Section 2.9 of [1], are not necessarily
   visible to the sending system.  These arguments suggest the use of a
   key management strategy based on RSVP router to RSVP router
   associations instead of IPSEC.

2.  Data Structures

2.1.  INTEGRITY Object Format

   An RSVP message consists of a sequence of "objects," which are type-
   length-value encoded fields having specific purposes.  The
   information required for hop-by-hop integrity checking is carried in
   an INTEGRITY object.  The same INTEGRITY object type is used for both
   IPv4 and IPv6.

   The INTEGRITY object has the following format:

      Keyed Message Digest INTEGRITY Object: Class = 4, C-Type = 1

       +-------------+-------------+-------------+-------------+
       |    Flags    | 0 (Reserved)|                           |
       +-------------+-------------+                           +
       |                    Key Identifier                     |
       +-------------+-------------+-------------+-------------+
       |                    Sequence Number                    |
       |                                                       |
       +-------------+-------------+-------------+-------------+
       |                                                       |
       +                                                       +
       |                                                       |
       +                  Keyed Message Digest                 |
       |                                                       |
       +                                                       +
       |                                                       |
       +-------------+-------------+-------------+-------------+




Baker, et al.               Standards Track