Exhibit 10.17 								 Nortel 					 Telephone: (408) 565-3635 (ESN 655) 							 Fax: 408 565-3325 29 January, 1997 Shiva Corporation 28 Crosby Drive Bedford, Mass 01730 Attn.: Cynthia Deysher RE: Memorandum of Understanding dated December 23, 1996 Northern Telecom Inc. and Shiva Corporation agree that the Memorandum of Understanding made as of December 23, 1996, between Northern Telecom Inc. and Shiva Corporation is amended by changing the date "January 31, 1997" in (i) line 3 of the last paragraph of the second page and (ii) Section 9.2 line 1 of the second paragraph to read "February 28, 1997." If you agree with the foregoing please sign and return the enclosed duplicate of this letter on or before January 31, 1997. Regards, /s/ Ken Heffner Ken Heffner Vice President, Multimedia Solutions Northern Telecom Inc. 2221 Lakeside Blvd. Richardson, Texas 75082 To: Northern Telecom Inc. We agree. Shiva Corporation /s/ Frank Ingari _______________________________ Signature