Hallgren, Michael michael.hallgren at
Wed Mar 20 20:27:21 UTC 2002

> On Wed, Mar 20, 2002 at 11:55:50AM -0800, Aditya wrote:
> > > I.e.: set TTL to 1 and your route only goes to your neighbors.
> > ie. community no-export
> Only if your neighbor listens to communities & does not strip any
> that they recieve.  [Someone at lunch mentioned one ISP that wanted
> a guarentee that their neighbor would not propogate some routes &
> did not want to rely on setting no-export as that breaks too often.]

Right. Genrally (from what I've seen around) community values signalled
might be taken in account when from customers... but rarely (only special
cases, like honoring MEDs by the way) from peers. Diverging experience and
opinions welcome.

> > so could you give an example where you wouldn't use 
> community no-export nor a
> > pre-agreed upon community between multiple AS (neighbors 
> and their neighbors)
> > that this would be useful? 
> You can use communities and cooperative configuration to make nearly
> anything work.  However this is not the case fairly often in
> practice.
> You can attempt to get this done via cooperation and try to enforce
> this by checking route-servers and adding Ts&Cs to contracts, but
> it sure would be a lot easier if the protocol just did it.  Its
> also a lot harder to get cooperation more than 1 AS hop away
> (assuming that you know all of those folks).



> 	--asp

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