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.
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.
Please note the evidently subtle point that, in this last case, any peering contract between V and X is not really applicable because this is not a peering relationship. I.e. surely any peering contract between V and X would not place terms or conditions on each other's possible relationship to, for example, MCI. randy