North American Network Operators Group

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Re: consistency and cix

  • From: Howard C. Berkowitz
  • Date: Fri Mar 27 15:34:08 1998

At 11:41 -0800 3/27/98, Randy Bush wrote:
>V peers with X at a number of points.  V and X announce the same routes
>to each other at all these points.
>V and X are also members of the CIX and are announcing routes to the CIX
>router.  X announces different routes to the CIX router than they
>announce directly to peer V because Y pays X to specifically announce
>Y's routes at the CIX.

Where did Y come from?  A Nike commercial?  Y ask Y? :-)  Personally, I
find numbers easier to follow than letters in these examples, don't U?  Is
the multihomed case W?

Slightly more seriously, a little more detail would help.

Is Y's space independent from both X and V? I could see V being unhappy if
X is advertising a more specific route in V's space, although this could be
reasonable if coordinated.

Does Y advertise its routes at any points other than through X?   Does Y
have a distinct ASN?

If Y is being advertised as part of X's AS, that seems to be a valid local
peering policy.
>Should V be unhappy with X's inconsistent route announcements?  Should
>X's announcement via the CIX be consistent with their announcements at
>the other points V and X meet?
>  o yes, because the CIX is a peering point, though router-based (this
>    in itself may be worth a different discussion).
>  o no, because in realty V and X each are paying customers of the CIX,
>    and the CIX is merely announcing their customers' routes to each
>    other.

Is the underlying issue that someone should announce all routes at an
exchange point?  It sounds as if V is complaining because X is selling
transit to Y.