<PAGE>
[DAY, BERRY & HOWARD LLP LETTERHEAD]
Exhibit 8.1
September 7, 2000
Sirocco Systems, Inc.
95 Barnes Road
Wallingford, Connecticut 06492
Ladies and Gentlemen:
We have acted as special tax counsel to Sirocco Systems, Inc., a
Delaware corporation ("Sirocco"), in connection with (i) the Merger, as defined
and described in the Agreement and Plan of Merger, dated as of June 5, 2000 (the
"Merger Agreement"), by and among Sycamore Networks, Inc., a Delaware
Corporation ("Sycamore"), Tropical Acquisition Corporation, a Delaware
corporation and a wholly-owned subsidiary of Sycamore, and Sirocco, and (ii) the
preparation and filing of the Registration Statement with the Securities and
Exchange Commission (the "Commission") under the Securities Act of 1933, as
amended (the "Act"), on August 14, 2000, and the Rule 424(b) Prospectus filed
with the Commission under the Act on August 16, 2000, which include the proxy
statement of Sirocco and the proxy statement and prospectus of Sycamore (the
"Proxy Statement/Prospectus"). At your request and pursuant to Section 7.1(g)
of the Merger Agreement, we are rendering our opinion concerning certain United
States federal income tax consequences of the Merger. Unless otherwise
indicated, each capitalized term used herein has the meaning ascribed to it in
the Merger Agreement.
In connection with this opinion, we have examined the Merger
Agreement, the Proxy Statement/Prospectus, and such other documents and
corporate records as we have deemed necessary or appropriate in order to enable
us to render the opinion below. We have relied, with the consent of Sycamore and
the consent of Sirocco, upon statements, representations, and covenants made by
Sycamore and Sirocco, including representations and covenants made to us by
Sycamore and Sirocco in their respective certificates dated as of the date
hereof and delivered to us for purposes of this opinion, and have assumed that
such statements and representations are true and complete without regard to any
qualifications as to knowledge and belief. For purposes of this opinion, we have
assumed (i) the validity and accuracy of the documents and corporate records
that we have examined and the facts and representations concerning the Merger
that have come to our attention during our engagement, (ii) that the Merger will
be consummated in the manner described in the Merger Agreement and the Proxy
Statement/Prospectus, and (iii) the genuineness of all signatures, the legal
capacity of all natural persons, the authenticity of all documents submitted to
us as originals, the conformity to original documents of all documents submitted
to us as certified or photostatic copies and the authenticity of the originals
of such documents.
<PAGE>
DAY, BERRY & HOWARD LLP
Sirocco Systems, Inc.
September 7, 2000
Page 2
In rendering our opinion, we have considered the applicable provisions
of the Code, Treasury Department regulations promulgated thereunder, pertinent
judicial authorities, interpretive rulings of the Internal Revenue Service (the
"IRS"), and such other authorities as we have considered relevant. It should be
noted that statutes, regulations, judicial decisions, and administrative
interpretations are subject to change at any time (possibly with retroactive
effect). A change in the authorities or in the accuracy or completeness of any
of the information, documents, corporate records, covenants, statements,
representations, or assumptions on which our opinion is based could affect our
conclusions. This opinion is expressed as of the date hereof, and we are under
no obligation to supplement or revise our opinion to reflect any changes
(including changes that have retroactive effect) (i) in applicable law or (ii)
in any fact, information, document, representation, corporate record, covenant,
statement, or assumption stated or referred to herein that becomes untrue,
incorrect, or incomplete.
Subject to the assumptions and qualifications set forth above, we are
of the opinion that the Merger will qualify as a reorganization within the
meaning of Section 368(a) of the Code.
The foregoing opinion does not address all of the United States
federal income tax consequences of the Merger. We express no opinion as to the
United States federal, state, local, foreign, or other tax consequences, other
than as set forth herein. Further, there can be no assurances that the opinion
expressed herein will be accepted by the IRS or, if challenged, by a court.
This letter is furnished to you solely for use in connection with the
Merger, as described in the Merger Agreement and the Proxy Statement/Prospectus,
and is not to be used, circulated, quoted, or otherwise referred to for any
other purpose without our express written permission.
Very truly yours,
/s/ Day, Berry & Howard LLP
Day, Berry & Howard LLP
