On Thu, Dec 13, 2001 at 10:30:39AM -0500, Kastenholz, Frank wrote:
> One of the problems with this whole area is that I've attempted
> to come up with a good, useful, crisp, definition of policy
> that covers what people are trying to do today with 'policy'.
> Unfortunately, policy is one of those N! things -- get N people
> in a room and you get N! definitions of policy. The lack of
> specificity and crispness of this section may be, I fear,
> a reflection of similar lacks in deployed networks. The
> only real requirement might be "operators have to be able
> to reach in and diddle with things"...
In the context of the current Internet, one could say there are
three components to policy:
1. Ingress policy - this controls what routes you accept from your
neighbors.
2. Route selection policy - this controls how you take the routes
you have available to use to make forwarding decisions.
3. Egress policy - this controls what routes you send to your neighbors.
These three components form the flow of routing, although routes
that are originated from the local router may start at step 2.
At each step, the route may be manipulated to change its properties.
These properties may be used to affect policy at a given stage,
either in the local speaker or some remote routing entity.
To effectively talk about policy past this abstraction, we need
to define the properties that the route has and the "expected"
behavior of how those properties will affect default route selection
in a remote routing entity or make available properties by which
they can exercise their own policy.
...
I'm very curious how we intend to approach "policy" in the next-generation
routing protocol. In the context of "privacy", policy is pretty
opaque from most providers - you can only see the results of it.
If policy is to remain opaque we are probably constraining ourselves
to something like the current Internet where things incrementally
converge.
> Frank Kastenholz
-- Jeff Haas NextHop Technologies
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