Why does Sprint have address filters again?

John Golovich said once upon a time:

In the Detroit area alot of smaller ISPs are looking to create a
peering between each other to create shorter router for wherever
traffic needs to go (ie. transit routing).

This plan has been placed on hold and almost officially shelved
because alot of the smaller ISPs dont see the need for an AS number.

It is like trying to get your budget increased. If the fee for AS
numbers was removed this peering would probably be already completed.

Couldn't you just use internal AS numbers to talk to each other? I agree,
its not the best solution, but it would at least get you on the road.

Seems to me they would need at least one ASN. But they could split the
cost of that one amongst themselves to make it more reasonable and use
private ASNs internally. BGP confederations are well documented. Of
course, your routers would have to support confederations. Otherwise, you
might (or might not) be able to do something like that manually depending
upon the filtering, etc. capabilities of your routers.