        NOTE: This disposition is nonprecedential.

  United States Court of Appeals
      for the Federal Circuit
               __________________________

            EXTREME NETWORKS, INC.,
              Plaintiff-Cross Appellant,
                             v.
           ENTERASYS NETWORKS, INC.,
               Defendant-Appellant.
               __________________________

                    2009-1325, -1346
               __________________________

   Appeals from the United States District Court for the
Western District of Wisconsin in case no. 07-CV-229,
Chief Judge Barbara B. Crabb.
             ___________________________

              Decided: September 30, 2010
              ___________________________

    MARGARET M. DUNCAN, McDermott Will & Emery
LLP, of Chicago, Illinois, argued for plaintiff-cross appel-
lant. With her on the brief were DAVID L. LARSON, of
Menlo Park, California; and JOEL M. FREED, NATALIA V.
BLINKOVA, and BUREDEN WARREN, of Washington, DC.

    DAVID P. SWENSON, Robins, Kaplan, Miller & Ciresi
L.L.P., of Minneapolis, Minnesota, argued for defendant-
appellant.   With him on the brief were SCOTT M.
EXTREME NETWORK   v. ENTERASYS NETWORK                  2


FLAHERTY; and CHRISTOPHER P. SULLIVAN, WILLIAM J.
ROCHA, REBECCA A. MACDOWELL and ALAN E. MCKENNA,
of Boston, Minnesota.
              __________________________

   Before RADER, Chief Judge, and LOURIE and PROST,
                    Circuit Judges.
RADER, Chief Judge.
    Extreme Networks, Inc. (“Extreme”) and Enterasys
Networks, Inc. (“Enterasys”) accuse each other of patent
infringement. The United States District Court for the
Western District of Wisconsin granted summary judg-
ment of non-infringement of Enterasys’s patents: U.S.
Patent Nos. 5,430,727 (“’727 patent”) and 5,195,181 (“’181
patent”). Extreme Networks, Inc. v. Enterasys Networks,
Inc., 558 F. Supp. 2d 909, 924 (W.D. Wis. 2008). Before
proceeding with trial on Extreme’s infringement claims,
the district court granted Extreme’s motion to exclude
Enterasys’s expert from testifying. Extreme Networks,
Inc. v. Enterasys Networks, Inc., No. 07-cv-229, 2008 WL
4621440, at *2 (W.D. Wis. May 16, 2008). After the jury
trial, the district court entered a final judgment of in-
fringement against Enterasys, but denied Extreme’s
motion for attorney fees. See Extreme Networks, Inc. v.
Enterasys Networks, Inc., No. 07-cv-229, 2008 WL
4756498, at *6-7 (W.D. Wis. Oct. 29, 2008).
    Because the district court erroneously construed the
contested limitation “digest of information,” this court
vacates the summary judgment as to the ’181 patent.
This court also vacates the denial of Extreme’s motion for
attorney fees. In all other respects, this court affirms.
                            I
   The ’727 patent— “Multiple Protocol Routing”—issued
3                 EXTREME NETWORK    v. ENTERASYS NETWORK


on July 4, 1995, based on a May 19, 1994 application. The
’727 patent covers a “brouter,” which can operate both as
a bridge and a router. Claims 5, 6, and 7 of the ’727
patent are at issue on appeal. Claim 5 is representative
and recites:
    A device which is capable of acting as a router to
    forward to and from end systems user data pack-
    ets and is capable of acting as a bridge to forward
    between networks user data packets, said device
    comprising
       router circuitry causing said device to act as a
       router recognizing and forwarding user data
       packets conforming to a first protocol suite,
       bridge circuitry causing said device to act as a
       bridge recognizing and forwarding user data
       packets conforming to at least a second proto-
       col suite,
       control circuitry causing said device to act as a
       bridge rather than as a router for a user data
       packet which conforms to said first protocol
       suite and is addressed to a single address
       which is not an address of the device.
’727 patent col.60 ll.20-34 (emphasis added).     Claims 6
and 7 depend from claim 5.
    The ’181 patent—“Message Processing System Having
Separate Message Receiving and Transmitting Processors
with Message Processing Being Distributed Between the
Separate Processors”—issued on March 16, 1993, based
on a January 10, 1992 application. The ’181 patent
provides a scheme for partitioning workload between
receive and transmit processors so that a data packet can
quickly and efficiently move through a multiprocessor
system.    Each receive processor collects information
EXTREME NETWORK   v. ENTERASYS NETWORK                   4


relating to the network protocol processing of a particular
data packet into a “digest.” ’181 patent col.4 ll.57-62.
“The information placed in the digest comprises informa-
tion that is necessary for the completion of the processing
tasks to be performed by the [transmit processors].” Id.
col.4 ll.62-65.
   Claims 1, 6, and 7 of the ’181 patent are at issue on
appeal. Claim 1 is representative and recites:
   A computer system for transmitting messages in a
   computer network, which comprises:
       a message receiving processor adapted to re-
       ceive messages from the computer network;
       a separate message transmitting processor
       coupled to the message receiving processor;
       the message receiving processor operating to
       perform first preselected processing of a mes-
       sage received by the message receiving proc-
       essor and to generate a digest of information
       relating to the message, the digest containing
       network protocol processing information for
       message transmit processing;
       the message receiving processor transmitting
       the message and the digest o [sic] the message
       transmitting processor;
       the message transmitting processor operation
       to perform second preselected processing of
       the message using the network protocol proc-
       essing information in the digest.
’181 patent col.12 ll.50-68 (emphases added).
                            II
   On April 20, 2007, Extreme sued Enterasys alleging
5                 EXTREME NETWORK    v. ENTERASYS NETWORK


infringement of three Extreme patents. On May 30, 2007,
Enterasys counterclaimed, alleging infringement of the
’727 patent, the ’181 patent, and a third patent, which
Enterasys later voluntarily dismissed. On May 5, 2008,
the district court granted summary judgment of non-
infringement of the ’727 patent based on its construction
of the terms “acting as a bridge” and “bridge circuitry.”
The district court also granted summary judgment of non-
infringement of the ’181 patent based on its construction
of the term “digest.” The district court thus disposed of
Enterasys’s infringement claims.
    Before holding a trial on Extreme’s infringement
claims, the district court granted Extreme’s motion in
limine to preclude Enterasys’s expert Barbara Frederik-
sen from testifying in support of its noninfringement and
invalidity defenses. Extreme obtained a verdict in the
amount of $201,213. The district court denied Extreme’s
motion for attorney fees.
    Enterasys appeals the district court’s grant of sum-
mary judgment of non-infringement of the ’727 and ’181
patents and its decision to exclude Frederiksen’s expert
testimony. Extreme cross-appeals the denial of its motion
for attorney fees.
                            III
     As an initial matter, Extreme argues that this court
does not have jurisdiction over this appeal because En-
terasys’s notice of appeal was untimely. The district court
entered judgment on November 5, 2008. The parties then
filed post-trial motions, including motions to calculate
pre-judgment interest, post-judgment interest, and sup-
plemental damages. The district court entered an order
disposing of all such motions on March 16, 2009. The
court clerk entered an amended judgment on March 19,
2009. Enterasys filed its notice of appeal on April 17,
EXTREME NETWORK    v. ENTERASYS NETWORK                     6


2009. Extreme argues that the November 5, 2008 order
was a final judgment and that the time to file an appeal
re-started on March 16, 2009. If Extreme’s assumptions
were correct, Enterasys’s notice of appeal, which was filed
more than thirty days after the March 16, 2009 order,
would be untimely.
    A final judgment “ends the litigation on the merits
and leaves nothing for the [district] court to do but exe-
cute the judgment.” Crown Packaging Tech., Inc. v.
Rexam Beverage Can Co., 559 F.3d 1308, 1311 (Fed. Cir.
2009) (citation omitted). Where substantive issues re-
main unresolved, a “judgment standing alone as issued by
the district court [is] insufficient to establish dismissal of
the entire action and . . . could not be the basis for provid-
ing [the Federal Circuit] with subject matter jurisdiction.”
SafeTCare Mfg., Inc. v. Tele-Made, Inc., 497 F.3d 1262,
1267 (Fed. Cir. 2007).
     “Prejudgment interest is an element of complete com-
pensation.” West Virginia v. United States, 479 U.S. 305,
310 (1987). “Prejudgment interest serves to compensate
for the loss of use of money due as damages from the time
the claim accrues until judgment is entered, thereby
achieving full compensation for the injury those damages
are intended to redress.” Id. at 310 n.2. Therefore, courts
should calculate prejudgment interest before determining
the amount of damages that would fully compensate the
patentee for the infringer’s use of the patented invention.
    The November 5, 2008 judgment did not constitute a
final judgment because it left unresolved prejudgment
interest, even though the parties had previously notified
the district court of their unresolved dispute over its
calculation. The district court did not calculate prejudg-
ment interest until the March 16, 2009 order. Because
the March 19, 2009 amended judgment resolved all pend-
7                  EXTREME NETWORK     v. ENTERASYS NETWORK


ing issues, under the facts of this case, it is the only final
judgment. Because Enterasys filed its notice of appeal
within thirty days thereafter, this court has jurisdiction.
                             IV
    Summary judgment is appropriate when “the plead-
ings, depositions, answers to interrogatories, and admis-
sions on file, together with the affidavits, if any, show
that there is no genuine issue as to any material fact and
that the moving party is entitled to a judgment as a
matter of law.” Fed. R. Civ. P. 56. Thus, a court may
grant summary judgment “when no reasonable jury could
return a verdict for the nonmoving party.” Revolution
Eyewear, Inc. v. Aspex Eyewear, Inc., 563 F.3d 1358, 1365
(Fed. Cir. 2009) (citations omitted). This court reviews a
grant of summary judgment of non-infringement without
deference. O2 Micro Int’l, Ltd. v. Monolithic Power Sys.,
467 F.3d 1355, 1359 (Fed. Cir. 2006). This court also
reviews claim construction without deference. Cybor
Corp. v. FAS Techs., Inc., 138 F.3d 1448, 1456 (Fed. Cir.
1998) (en banc).
     Claims 5, 6, and 7 of the ’727 patent include the limi-
tation: “bridge circuitry causing said device to act as a
bridge recognizing and forwarding user data packets
conforming to at least a second protocol suite.” ’727
patent col.60 ll.20-39. The district court held that the
brouter “recognizes” the type of protocol suite to which a
data packet belongs and decides whether to forward the
data packet as a bridge or a router based on the protocol
suite. The district court granted summary judgment of
non-infringement because it found that the accused
Extreme devices do not base their decisions on the proto-
col suite.
    The district court correctly construed the “bridge cir-
cuitry” limitation. The parties agree that the brouter has
EXTREME NETWORK   v. ENTERASYS NETWORK                    8


some decision-making capabilities. The claim language
implies that the recognition of the second protocol suite
triggers the brouter’s decision to act as a bridge or a
router because it does not specify any other criteria by
which the brouter can determine how it will forward the
data packets.
    The specification supports this interpretation of
“bridge circuitry.” The only disclosed embodiment of a
brouter “is arranged to treat TCP/IP packets as if the
router were a normal IP router and to treat all other
packets as if the router were a bridge.” ’727 patent col.50
l.67-col.51 l.2. The brouter treats a data packet conform-
ing to TCP/IP by routing it and a data packet conforming
to a different protocol suite by bridging it. The specifica-
tion does not disclose any other basis for deciding whether
to route or bridge a data packet. Although this court
must be careful not to read an embodiment into a claim,
the specification of the ’727 patent supports the causal
connection between the recognition of the data packet’s
protocol suite and the determination whether to act as a
router or a bridge. Accordingly, the district court cor-
rectly held that the claimed brouter must make a decision
whether to bridge or route a data packet based on the
protocol suite to which the data packet conforms.
     Enterasys also argues that there is a genuine issue of
material fact as to how Extreme’s accused devices decide
whether to route or bridge a data packet. In its summary
judgment motion, Extreme argued that its devices for-
ward the incoming data packets regardless of their proto-
col suites. In response, Enterasys merely alleged that the
accused devices ascertain the data packets’ protocol suites
before routing or bridging them. Enterasys made no
attempt to establish that the determination of the proto-
col suite has any bearing on the devices’ decision to “act
as a bridge.” Accordingly, there is no genuine issue of
9                  EXTREME NETWORK    v. ENTERASYS NETWORK


material fact.
    Finally, Enterasys argues it is entitled to pursue addi-
tional discovery on Extreme’s devices because the district
court changed its claim construction of “bridge circuitry”
over time. The district court did not change its construc-
tion of “bridge circuitry.” Also, this court finds that
Enterasys could have conducted its discovery in anticipa-
tion of the final claim construction. Enterasys never
sought relief on the ground that it had been unable to
obtain the necessary discovery to dispute that Extreme’s
devices do not use the protocol suite in deciding how to
forward data packets. Enterasys had a full opportunity to
take the discovery it now demands. Thus, Enterasys is
not entitled to additional discovery. Accordingly, this
court affirms the summary judgment of non-infringement
of the ’727 patent.
                             V
    Claims 1, 6, and 7 of the ’181 patent recite: “the mes-
sage receiving processor . . . to generate a digest of infor-
mation relating to the [received] message, the digest
containing network protocol processing information for
message transmit processing.” ’181 patent col.12 ll.50-68,
col.14 ll.18-43. The district court explained in its sum-
mary judgment order that because the digest “contain[s]”
network protocol processing information, “the digest is a
structure and not the contents of the structure.” Extreme
Networks, 558 F. Supp. 2d at 920. The district court
granted summary judgment of non-infringement based on
Enterasys’s alleged concession that Extreme’s devices do
not have such a structure.
    The parties agree that the term “digest” does not have
a specific definition in the relevant art. The term “digest”
ordinarily means a collection of information. See Mer-
riam-Webster’s Collegiate Dictionary (10th ed. 1993)
EXTREME NETWORK    v. ENTERASYS NETWORK                     10


(defining “digest” as “a summation or condensation of a
body of information”); Random House Webster’s College
Dictionary (1991) (defining “digest” as “a collection or
compendium, as of literary or scientific matter,
esp[ecially] when classified or condensed”). A “digest,”
which is a condensation of a body of information relating
to the received message, would logically be a set of data
rather than a structure containing that data. The district
court erred by focusing on the claim term “containing”
and concluding that something “containing” information
cannot also be information. To the contrary, the term
“containing” does not indicate whether the “digest” is a
structure or the contents of a structure.
    Moreover, the following passage in the specification
clarifies that a “digest” is a collection of information
relating to network protocol processing of a particular
message:
    [T]he present invention arranges each [receiving
    processor] to collect, into a digest, information re-
    lating to network protocol processing of a particu-
    lar message, obtained via sequential byte
    processing of the message at the time of reception
    of the message. . . . [This] digest can include, for
    example, certain information from the data link
    layer header of a received message. The data link
    information can include, for example, last hop in-
    formation that is used by the processor of the
    transmitting line interface card in the transmis-
    sion of the message.”
’181 patent col.4 ll.57-62, col.4 l.68-col.5 l.5 (emphases
added). “[The] digest can include . . . certain information”
just like “[t]he data link information can include . . . last
hop information.” Id. This parallel language further
suggests that the digest, like the data link information, is
11                 EXTREME NETWORK   v. ENTERASYS NETWORK


information. Specifically, the digest contains “network
protocol processing information” that is related to process-
ing of the message but may contain other information
that could assist other processors in processing the mes-
sage. Accordingly, this court vacates the summary judg-
ment of non-infringement of the ’181 patent.
                            VI
    Enterasys has the burden of establishing that
Frederiksen’s expert testimony is admissible based on her
“knowledge, skill, experience, training, or education” in
the relevant technology. Fed. R. Evid. 702. Courts must
determine whether expert testimony is reliable by assess-
ing whether the expert is qualified in the relevant field.
Smith v. Ford Motor Co., 215 F.3d 713, 718 (7th Cir.
2000). A district court’s decision to preclude expert testi-
mony is an evidentiary issue, which this court reviews
under the law of the regional circuit. Research Corp.
Techs. V. Microsoft Corp., 536 F.3d 1247, 1255 (Fed. Cir.
2008). The U.S. Court of Appeals for the Seventh Circuit
reviews evidentiary rulings for an abuse of discretion.
Von Der Ruhr v. Immtech Int’l, Inc., 570 F.3d 858, 862
(7th Cir. 2009).
    The district court did not abuse its discretion by ex-
cluding Frederiksen’s testimony on the ground that she
was not qualified as an expert in the relevant art. Both
parties agree that a person of ordinary skill in the art
pertinent to Extreme’s patents would have a substantial
background in switches, bridges, and routers. Frederiksen
opined that an ordinary artisan was:
     An individual with a Bachelor of Computer Sci-
     ence or computer engineering degree, or equiva-
     lent experience, and 2-3 years experience in the
     computer industry working on the design or devel-
     opment of high speed switches, bridges, or routers
EXTREME NETWORK   v. ENTERASYS NETWORK                  12


   for wide area networks (e.g. frame relay, ATM);
   local area networks (e.g. Ethernet, FDDI, token
   ring, etc.); or military networks.
(J.A.1350-01 (emphasis added)). Extreme’s expert, Dr.
Nathaniel Davis, identified a similar set of criteria for
defining the person of ordinary skill, although his defini-
tion included somewhat more industry experience.
     Frederiksen would not qualify as a person of ordinary
skill in the relevant art even under her own proposed
definition. Frederiksen received an Associate of Applied
Science degree in Computer Programming. She worked
as a system administrator for several corporations, but
she never seems to have worked on “the design or devel-
opment of high speed switches, bridges, or routers.”
General experience in a related field may not suffice when
experience and skill in specific product design are neces-
sary to resolve patent issues. See, e.g., Flex-Rest, LLC v.
Steelcase, Inc., 455 F.3d 1351, 1360-61 (Fed. Cir. 2006)
(affirming exclusion of an ergonomics expert where the
invention at issue related to an ergonomic keyboard
design). Therefore, the district court did not abuse its
discretion by ruling that Frederiksen was an unqualified
expert.
                           VII
    This court affirms the summary judgment of non-
infringement of the ’727 patent and the decision to ex-
clude Frederiksen’s expert testimony. This court vacates
the summary judgment of non-infringement of the ’181
patent and thus vacates the denial of Extreme’s motion
for attorney fees as premature given the fact that in-
fringement of the ’181 patent may need to be redecided.
This court remands the case for further proceedings
consistent with the opinion.
13              EXTREME NETWORK   v. ENTERASYS NETWORK


     AFFIRMED-IN-PART, VACATED-IN-PART, AND
                   REMANDED
