I did observe 2 exchange points have direct connection between them, does it mean they belong to the same switch fabiric? What does this mean?
I mean in a trace (from traceroute probing), 2 exchange points (in Mr Woodcock's list) are next to each other.
.... ip of AS1, ip of EP1, ip of EP2, ip of AS2, ....
I thought they are connected to each other directly (probably the connecion is not as simple as the p2p link between 2 routers).
I 'spect that you are seeing something like secondary IP s on the same phys interface.
Are those private peering points?
confusion of terms. When bits cross an administrative boundary [...]
Sorry, I did confuse peering with transit. But I thought those private peering points are somewhat similiar too the IXs, ISPs exchange traffic there and they may also provide transit to the customers there.
Nope. You remain confused. exchanges are not "peering" or "transit" or a floor wax. ISP policies determine if they propgate routes or not and if they are willing to propogate third party routes e.g. routes not originated by their direct neighbors. exchanges are just a way to interconnect between ISPs.
So. Is this one exchange point (one switch), four exchange points ( 4 VLANS), or five exchange points ( 5 subnets)? Which ones are public? Which ones are private? and why?
Is this case very common?
More than you would want to beleive. Now answer the question. --bill