Appeal No. 2004-0852
Application No. 09/354,651 Page 8
cyclic-redundancy-code (CRC). The header includes link-level
(hardware) addresses of PE2s and CE2s. The code represents IP,
and the receiving router interprets the contents as an IP
datagram. However, the type field does not include the IP
indicating code. Instead, the code tells the PE2 interface that
the frame's contents should be interpreted as a tagged packet
(col. 7, lines 23-65). Assuming that PE2 sends a packet to P2,
P2 knows to forward the packet to neighboring router P1. Note
that P2 is able to make this decision without having to maintain
separate routing information for the VPN to which the packet is
ultimately destined (col. 8, lines 15-24). Rekhter further
discloses that every router runs an Internet Gateway Protocol
(IGP). From time to time, a router sends to its same-domain
neighbor routers IGP messages that advertise destinations to
which it accords direct access. The neighbors in turn forward
the messages to their neighbors. The next hop is always a
directly connected neighbor (col. 11, lines 7-22).
From the disclosure of Rekhter, we agree with appellants
that the references to TCP/IP in Rekhter are in the context of
communications between neighboring routers, and not between
endpoints. From Rekhter's disclosure of communications between
directly connected neighboring routers, we do not agree with the
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