Comments on alternatives

[Joel Halpern <[e-mail]>]

Having posted some of the difficulties to the list, I certainly agree that
there are some problems with our transit-router to transit-router
behavior.

There are several possible approaches to the solution.

1) Rifs/BGP Queries are a methodology outlined in an ID.  The primary
    concern I have with this particular methodology is its interaction
    with multiple levels of aggregation.  If there are multiple levels,
    one is required to make several queries and maintain several
    "relationships" with aggregating routers.  This seems to be significant
    overhead.

2) NHRP with state exchange could be used in certain situations.  If both
    ends are BGP routers (or both are intra-domain routers within the same
    domain) a degenerate exchange between the two will allow the detection
    of routing loops, and their removal.
2a) In order to do this however, we would also have to specify what happens
    when the query crosses the intra/inter border.  Is it terminated.  Is
    the query propagated, and the response replaced if it turns out to be
    router-router?  (There are enough bits to tell this.)  Or is there
    something else to do in this case.

3) Or should we punt the whole thing back to a query that ONLY works for
    host resolution.  I personally would like a mechanism which worked
    for host-host, host-router, and appropriate router-router if that can
    be determined safely and reliably.

Thank you,
Joel M. Halpern				[e-mail]
Newbridge Networks Inc.