RFC 2103 (rfc2103) - Page 3 of 17

Mobility Support for Nimrod : Challenges and Solution Approaches

RFC 2103                Nimrod Mobility Support            February 1997


   Thus, providing a solution to mobility in the context of Nimrod may
   be perceived as one of maintaining a dynamic association between the
   endpoints and the locators.  Extending this viewpoint further, one
   can think of mobility-capable Nimrod as essentially consisting of two
   "modules":  the Nimrod routing module and the dynamic association
   module (DAM). The DAM is an abstraction, embodying the functionality
   pertinent to maintaining the dynamic association.  This is a valuable
   paradigm because it facilitates the comparison of various mobility
   schemes from a common viewpoint.  Our discussion will be structured
   based on the DAM abstraction and will be in two parts, the themes of
   which are :

   o What constitutes mobility for the DAM and Nimrod?  Is the
     realization of mobility as a mobility "module" that interacts
     with Nimrod viable? What then are the interactions between
     Nimrod and such a module?  These points will be discussed in
     section 3.

   o What are some of the approaches one can take in engineering the DAM
     functionality?  We classify some approaches and compare them in
     section 4.

   A word of caution:  the DAM should not be thought of as something
   equivalent to the current day Domain Name Service (DNS) - the DAM is
   a more general concept than that.  For instance, consider a mobility
   solution for Nimrod similar to the scheme described in [Sim94].  Very
   roughly, this approach is as follows:  Every endpoint is associated
   with a "home" locator.  If the endpoint moves, it tells a "home
   representative" about its new locator.  Packets destined for the
   endpoint sent to the old locator are picked up by the home
   representative and sent to the new locator.  In this scheme, the DAM
   embodies the functionalities implemented by all of the home
   representatives in regard to tracking the mobile hosts.  The point is
   that the association maintenance, while required in some form or
   other, may not be an explicitly distinct part, but implicit in the
   way mobility is handled.

   Thus, the DAM is merely an abstraction useful to our discussion and
   should not be construed as dictating a design.

   In summary, we view the Nimrod architecture as carrying a functional
   "stub" for mobility, the details of the stub being deferred for
   later.  The stub will be elaborated when a solution that meets the
   requirements of Nimrod becomes available (for instance from the IETF
   Mobile-IP research).  We do not, however, preclude the modification
   of any such solutions to meet the Nimrod requirements or preclude the
   development of an independent solution within Nimrod.




Ramanathan                   Informational