ANS to CIX Interconnection

mak mak
Thu Oct 1 01:55:23 UTC 1992

  You may be overestimating the problem. This is only an issue for regionals
who are using default. If you are routing via explicit announcements
from the backbone, it is a simple matter for us to filter out the
AS 1957 announcement to exclude this traffic. Or alternatively you
can do this in your peer router. 
  For regionals using default, it isn't possible to prevent traffic
from being sent from the regional to the CIX. One might think that
it would be possible to prevent traffic in the other direction by
filtering the announcement of that regional's networks by the
backbone to the CIX. But this is also not possible since the CIX
member networks are pointing default at the NSFNET backbone. So
routing will be asymmetric but it will work. I can make available
a postscript picture of the whole routing situation, if that would help.
  As far as whether this process has been open or not, first I should
say that this is not really a Merit/NSFNET issue. It is an agreement
between ANS (our subcontractor) and the CIX. As NSFNET service provider
we are trying to facilitate this interconnection for the benefit of
regionals. We were involved in the discussions of routing design
(in fact Jessica Yu provided quite a lot of consulting with this)
but the requirements were laid out by ANS and CIX. BARRnet and
NEARnet were involved, as they are both ANS and CIX members and
will make use of this interconnection.
  In any case we haven't made the change yet and I am certainly open
to constructive (or even other types of) suggestions. We are currently
working on verifying the integrity of the list of nets within AS 1957
and finalizing the confirmations with the current AS's for the database.
The actual configuration date is at least a week or two away. Let me
know if this helps or not.

> From:    "Milo S. Medin" (NASA ARC NSI Office) <medin at>
> To:      mak at
> CC:      bjp at, regional-techs at

> Mark, the issue as I see it is that the current plan for implementing
> CIX connectivity is a change from the previous policy, and that you are
> now shifting responsibility for ensuring this filtering from your routers
> to the regionals, which for the regional, may involve significant 
> administrative load, and which is the organization best capable of dealing
> with that administrative load. 
> Further, there is also the issue that this plan does not appear to have been
> developed in a cooperative fashion with the regionals and other peers network
> as a whole, as past shifts of functionality and responsibility between
> the backbone and regionals were done.
> I think there is not uniform consensus that the approach described is the
> best way of accomplishing the end goal, which also hasn't been described
> in a very explicit way, and is complicated by goals that NSF has and 
> potentially other goals that ANS itself has.  I'm not saying there is a confl
> here, just that the precise goals and objectives do not appear to be well
> understood by all parties involved.  This of course leads to confusion, which
> in turn will impede progress on any approach selected.  It's hard to judge 
> when you've got a good design if you don't understand what the requirements
> for the design are!
> Please feel free to correct me if I'm off base here.  This is just my 
> perception at this point, and I'm really not trying to throw stones, just
> trying to make sure evryone is working together on getting the job done
> right.  
> 						Thanks,
> 						   Milo

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