Appeal 2007-1099
Application 09/955,469
ordinary skill in the art would employ.” KSR Int’l Co. v. Teleflex Inc., 127
S. Ct. 1727, 1741, 82 USPQ2d 1385, 1396 (2007) (quoting In re Kahn, 441
F.3d 977, 988, 78 USPQ2d 1329, 1336 (Fed. Cir. 2006)).
We begin our analysis by noting that Bruck teaches a scalable load-
balancing solution for server clusters that replaces a prior art single load-
balancing computer (see col. 2, ll. 6-35). The prior art single load-balancing
computer disadvantageously provided a single point of failure (id.). We note
that Bruck teaches a front server layer (see Fig. 2, servers 206, 208, 210, and
212) and a back-end server layer (see Fig. 2, servers 220, 222, 224, and
226). In particular, Bruck teaches the front server layer performs fail-over
and dynamic load balancing for both server layers (col. 2, ll. 44-45). Bruck
teaches the back-end servers function as Web file servers, FTP servers, or
application servers (see Fig. 2, servers 220, 222, 224, and 226, see also col.
2, ll. 38-43).
Bruck further teaches the front server layer provides a resilient
network connection in which network addresses can be moved among the
cluster machines without breaking network connections between clients and
the servers (see col. 2, l. 66 through col. 3, l. 3, emphasis added). In
particular, Bruck teaches “the system provides symmetric routing of network
traffic, guaranteeing that the incoming and outgoing traffic of the same
network connection goes through the same front-layer server” [i.e., in the
absence of a front-layer server failure] (see col. 3, ll. 15-18, col. 6, ll. 61-65,
emphasis added).
In the case of a front-layer server failure, Bruck teaches the server
cluster provides a distributed network address translation (NAT) function
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