Appeal No. 1999-2380
Application No. 08/575,743 Page 11
have found no teaching or suggestion within Futral that a third
state of uncertainty is recognized for either source addresses or
destination addresses."
We find that in Futral (col. 11, lines 7-10) "[t]he filter
unit 28 must be able to differentiate between source and
destination addresses, and the mode nits 100 are used for this
purpose." In addition (id., lines 28-35) Futral discloses that:
The information contained in the database DB on
the various nodes in networks A and B permit the filter
to exercise a certain modicum of security; that is,
messages may be forwarded from one network to the other
only if (1) the source node is authorized to use the
bridge 12, and/or (2) the destination node on one of
the networks (e.g., network B) is authorized to receive
dataframes from another network (e.g., network A).
In addition (id., lines 42-64), in the secure destination address
mode, if the record in the database DB corresponding to the
destination address DA of the dataframe under analysis by the
filter unit 28 is found, the mode control field must be that of a
destination class. If the address is not found, or if the mode
bits do not indicate a destination class, then the Copy command
is not issued. In similar fashion, after the destination address
is checked, the database DB is searched for the occurrence of a
record corresponding to a source address SA contained in the
dataframe under analysis. If the record is found, the mode
control bits of that record are looked at to determine if they
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