Re: Addr: Local Preference Computation

[Joel Halpern <[e-mail]>]

I have been reading the local-pref/MED discussion, and trying to tie it
back to my understanding of the assumptions that had been made originally.

As I understood things, the point of "local-pref" was to ensure that all
border routers of an AS made the same choice of path for a given destination. 
This would then allow the appropriate BGP advertisement to be generated by
all AS boundary routers.

If I am reading the discussion right, the routing loops occur because
the local-pref value is not sthe only thing being used.  Therefore, 
internal routers (who do not have the full policy of the external border
routers) are getting confused about what is happening?

1) I would strongly suggest that the discussion would be helped by an 
    explicit statement in each proposal of how the fields (MED an and 
    local-pref) are to generated and compared for route selection.
2) If the old assumptions are no longer applicable, I would appreciate
    an explanation of why.  The most obvious cause would be that some
    underlying precept turns out not to be the case.  For example, the
    local-pref stuff is basically based on assuming similarity of policy
    mechanisms on all border routers of an AS. Does that no longer obtain?

Yours, with apologies for not being as current on some of the thinging as
I should be,
Joel M. Halpern			[e-mail]
Newbridge Networks Inc.