RFC 2103 (rfc2103) - Page 3 of 17
Mobility Support for Nimrod : Challenges and Solution Approaches
Alternative Format: Original Text Document
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