In the referenced message, Jared Mauch said:
You may want to consider using tftp/rcp/whatnot loaded
files for this.As it loads [most if not all depending on the config length] all
of the config then parses it promptly.this will prevent leakage in rare cases.
- jared
I have noted that even tftp-loaded files run the risk of a BGP scan
occuring between the parsing of "no access-list foo" and the parsing
of the first "access-list foo" line. It appears Brand C takes the
non-existance of an access-list to mean "implicit permit". I think this
is probably the source of much of the seen mini-leaks.
As someone else mentioned, prefix-lists (again brand C) do allow for
insertion and deletion of individual items at "any" point in the list,
so may be a good workaround. However, if you are doing anything at all
"interesting" in your acls, it becomes a lot more difficult to translate
over to prefix-lists.
One major item that seems missing is the ability to match less-specifics.
There are certain instances when this would be really nifty. Brand C
extended acls, and Brand J prefix-lists seem to be able to partially cover
this, but not perfectly.