1 EXHIBIT 23.1 CONSENT OF INDEPENDENT AUDITORS We consent to the incorporation by reference in the Registration Statement (Form S-8) pertaining to the Telco Systems, Inc. Amended and Restated 1990 Stock Option Plan and certain Restricted Stock Grant Agreements of our report dated October 12, 1995, with respect to the consolidated financial statements and schedules of Telco Systems, Inc. included in its Annual Report (Form 10-K) for the year ended August 27, 1995, filed with the Securities and Exchange Commission. /s/ ERNST & YOUNG LLP ERNST & YOUNG LLP Boston, Massachusetts February 13, 1996