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); the Telco Systems, Inc. 1990 Stock
Option Plan (Form S-8 Nos. 33-42751, 333-00959 and 333-57581) and acquisition of
Jupiter Technology, Inc. (Form S-3 No. 333-46877) of our report dated November
4, 1998, with respect to the consolidated financial statements and schedule of
Telco Systems, Inc. for the year ended August 30, 1998 included in the Current
Report of Telco Systems, Inc. Form 8-K dated November 4, 1998, filed with the 
Securities and Exchange Commission.


                                                     /s/ERNST & YOUNG LLP

Boston, Massachusetts
November 5, 1998