Exhibit 99B

Power of Attorney

The undersigned hereby make, constitute and appoint each of David J. Kapnick and Steven D. Brooks, acting jointly or individually, with full power of substitution, the true and lawful attorney-in-fact for the undersigned, in the undersigned’s name, place and stead and on the undersigned’s behalf, to complete, execute and file with the United States Securities and Exchange Commission (the “Commission”), a statement on Schedule 13G or Schedule 13D with respect to the securities of any or all of the following entities:

Cogent Communications Group, Inc., a Delaware corporation; and

Proxim Corp., a Delaware corporation;

and any and all amendments thereto pursuant to Section 13(d) of the Securities Exchange Act of 1934, as amended, and the rules and regulations promulgated thereunder, and any other forms, certificates, documents or instruments (including a Joint Filing Agreement) that the attorneys-in-fact (or either of them) deems necessary or appropriate in order to enable the undersigned to comply with the requirements of said Section 13(d) and said rules and regulations.

This Power of Attorney shall remain in effect for a period of two years from the date hereof or until such earlier date as a written revocation thereof is filed with the Commission.

Dated: August 8, 2003
Broadview Capital Partners L.P.
	By:	Broadview Capital Partners Management LLC
	Its:	General Partner
	By:	/s/ David J. Kapnick
		David J. Kapnick
		Chief Financial Officer
Broadview Capital Partners Qualified Purchaser Fund L.P.
	By:	Broadview Capital Partners Management LLC
	Its:	General Partner
	By:	/s/ David J. Kapnick
		David J. Kapnick
		Chief Financial Officer
Broadview Capital Partners Affiliates Fund LLC
	By:	Broadview Capital LLC
	Its:	Manager
	By:	/s/ David J. Kapnick
		David J. Kapnick
		Chief Financial Officer

Broadview Capital Partners Management LLC
	By:	/s/ David J. Kapnick
		David J. Kapnick
		Chief Financial Officer
Broadview BCPSBS Fund L.P.
	By:	Broadview BCPSBS Fund LLC
	Its:	Manager
	By:	/s/ Paul F. Deninger
		Paul F. Deninger
		Manager
BCI Holdings, L.P.
	By:	Broadview Holdings LLP
	Its:	General Partner
	By:	/s/ Paul F. Deninger
		Paul F. Deninger
		Chief Executive Officer
Broadview Holdings LLP
	By:	/s/ Paul F. Deninger
		Paul F. Deninger
		Chief Executive Officer
/s/ Steven D. Brooks
Steven D. Brooks
/s/ Stephen J. Bachmann
Stephen J. Bachmann
/s/ Paul Deninger
Paul Deninger

2