1 EXHIBIT 23.1 Consent of Independent Auditors We consent to the incorporation by reference in the registration Statements pertaining to the Telco Systems, Inc. 1983 Employee Stock Purchase Plan (Form S-8 No. 33-26976); the Telco Systems, Inc. 1980 Stock Option Plan (Form S-8 Nos. 2- 94474, 33-2024 and 33-10548); the Telco Systems, Inc. 1988 Non-Statutory Stock Option Plan (Form S-8 No. 33-28295) and the 1990 Stock Option Plan (Form S-8 No. 33-42751) of our report dated October 12, 1995, with respect to the consolidated financial statements and schedules of Telco Systems, Inc. included in the Annual Report (Form 10-k) for the year ended August 27, 1995. ERNST & YOUNG LLP Boston, Massachusetts November 16, 1995