Internet Exchange Point(IXP) questions

Fri Feb 18 02:03:12 UTC 2011

I'm doing some research on multiple origin AS problems of IXPs. As I know,
generally there are two types of IXPs
type 1: use exchange routers, which works in layer 3
type 2: use switches and Ethernet topology, which works in layer 2.
So I have a couple of qustions:
1. For type 1, the exchange routers may use several IP prefixes for routing,
how often does the IP prefixes have their own AS?
2. For type 2, all peers connected to the IXP must work in the same subnet
required by Ethernet rules. Is possible that the subnet IP prefixes belong
to some private IP address space, such as 192.168.x.x? How often does this
happen? If the subnet only contains public IP addresses, how are the
addresses announced?

Thanks,
Yaoqing