RE: Next question...

["Tony Li" <Tony.Li@procket.com>]

|   > I suspect most of the complaints about host based locator 
|   selection is
|   > really an indirect fear of loss of control.
|   
|   i suspect it is folk with a knowledge of just how difficult 
|   and complex
|   global routing is when isolated to a site border router and 
|   our minds
|   boggle when we think of all the hosts having to do it too.


I have to disagree with both.  First, there is no way that
the site border router OR the host is going to have full information
about global routing.  They *might* have some limited policy
information and a mechanism to retrieve locators.

My concern is not so much about loss of control as it is with
the administrative burden of implementing the policies.  Most
policies are going to be site-wide, not host specific.  Having
to distribute this policy and keep it consistent across an
enterprise can be done by our standard system administration tools,
but the effort involved in doing so is non-trivial and the
number of exception hosts is likely to be small, so this just
seems like a poor ROI for the site administrator(s).

Our job, as architects, is not to create an architecture with
infinite flexibility.  Rather, it is to reject those options
which lead to unnecessary complications down the line.  Control
at the host seems like an infrequently used feature.  Note that
policy for a specific host can be implemented at either the 
site border router (SBR) or at the host, so removing the policy
decision from the host isn't actually eliminating architectural
flexibility.

Tony