Alpha test of MAE filtering capability

Tue Feb 4 14:13:45 UTC 1997

> 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