hypothetically, if mci enters into an agreement with MAE E/W to allow a list of mac header addresses to have access to our port on a gigaswitch, what reason is there for MAE E/W to share that list with anyone else?
Hypothetically, if MCI enters into an agreement with MFS to purchase a connection to a particular port of a GIGAswitch, what reason is there for MFS to share that port assignment with anyone else? See http://www.mfsdatanet.com/MAE/west.map.html with data like: Ames-Giga/2 198.32.136.12 mae-west.SanFrancisco.mci.net Certainly this data gives away *some* private information, but having that knowledge is often very useful when one discovers bizarre layer two problems. For instance, being able to ascertain that there is no packet loss from you to all devices on the same switch, and n% packet loss to all devices on another switch, without having to requests that MFS diagnose the apparent L3 problem, is very useful.
if there is no peering arrangement between two networks you could assume that the the mac header of one network's interface isn't on the list, right?
You could make that assumption, or perhaps that those two networks choose not to appear at that locality. You could also determine that information by sending a loose source-routed packet with a low ttl and watching where the time exceeded message comes from. Are there good operational reasons to make this data publically available? Do they outweigh the perceived privacy issues? It seems to me that there is no change in the "information leak" than is present in the status quo, and application of interconnect filtering is likely to cause a particular set of problems, some of which are obvious now ("A is on B's list and B is not on A's"), and some of which are perhaps a little more complicated (interactions with broadcast or multicast traffic, subtle distinctions in the way the GIGAswitch forwards frames to ports with filtering enabled, etc., etc.) wherein having this information would be valuable. --jhawk