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EXHIBIT 10.2

Execution Copy

AMENDMENT NO. 4

TO SECOND AMENDED AND RESTATED CREDIT AGREEMENT

        THIS AMENDMENT NO. 4 TO SECOND AMENDED AND RESTATED CREDIT AGREEMENT
(this "Amendment") dated as of September 30, 2002, is made among Cogent
Communications, Inc., a Delaware corporation ("Borrower"), Cogent Internet,
Inc., a Delaware corporation ("Additional Borrower"), Cogent Communications
Group, Inc., a Delaware corporation ("Holdings"), and Cisco Systems Capital
Corporation, a Nevada corporation ("Lender" or "Agent").

        WHEREAS, Borrower, Additional Borrower, Agent and the several financial
institutions from time to time party thereto ("Lenders") entered into a Second
Amended and Restated Credit Agreement dated as of October 24, 2001, as amended
by that certain Amendment No. 1 to Second Amended and Restated Credit Agreement
dated as of February 4, 2002, Amendment No. 2 to Second Amended and Restated
Credit Agreement dated as of April 17, 2002, and Amendment No. 3 to Second
Amended and Restated Credit Agreement dated as of October 1, 2002 (as amended,
the "Credit Agreement");

        WHEREAS, in order to clarify the Credit Agreement, Borrower, Additional
Borrower, Holdings and Agent desire, in accordance with Section 8.1 of the
Credit Agreement, to amend the Credit Agreement.

        NOW, THEREFORE, in consideration of the premises, the mutual covenants
herein contained, and other good and valuable consideration, the receipt of
which is hereby acknowledged, the parties hereto agree as follows

        SECTION 1    Definitions; Interpretation.    

        (a)    Terms Defined in Credit Agreement.    All capitalized terms used
in this Amendment (including in the recitals hereof) and not otherwise defined
herein shall have the meanings assigned to them in the Credit Agreement.

        (b)    Interpretation.    The rules of interpretation set forth in
Section 1.2 of the Credit Agreement shall be applicable to this Amendment and
are incorporated herein by this reference.

        SECTION 2    Amendments to the Credit Agreement.    

        (a) Section 5.1(r)(ii) of the Credit Agreement is hereby deleted in its
entirety and replaced with the following:

Minimum Total Revenue. On a consolidated basis, Holdings and its Subsidiaries
shall not fail to maintain total monthly, total quarterly or total annualized
quarterly revenue of Holdings and its Subsidiaries, for each monthly or
quarterly period, as applicable, set forth below, of not less than the
correlative amount indicated (it being understood that with respect to any
quarterly period for which annualized amounts are required, annualized revenue
shall be equal to revenue for such quarterly period, multiplied by four):

Monthly Period Ending
(excluding revenue generated
by assets that were acquired
by Holdings and its
Subsidiaries pursuant to the
Asset Purchase Transaction)

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  Required Amount

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March 31, 2002   $ 1,200,000 April 30, 2002   $ 1,500,000 May 31, 2002   $
1,900,000 June 30. 2002   $ 2,200,000 July 31, 2002   $ 2,600,000 August 31.
2002   $ 3,100,000 September 30, 2002     N/A

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Monthly Period Ending

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Required Amount

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March 31, 2002   $ 1,200,000 April 30, 2002   $ 4,400,000 May 31, 2002   $
4,500,000 June 30, 2002   $ 4,400,000 July 31, 2002   $ 4,700,000 August 31,
2002   $ 5,200,000 September 30, 2002     N/A

Quarterly Period Ending

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Required Amount

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December 31, 2002   $ 15,500,000

Quarterly Period Ending

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Required Annualized Amount

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March 31, 2003   $ 109,300,000 June 30, 2003   $ 142,700,000 September 30, 2003
  $ 182,000,000 December 31, 2003   $ 228,000,000 March 31, 2004   $ 280,300,000
June 30, 2004   $ 335,400,000 September 30, 2004   $ 393,200,000 December 31,
2004   $ 453,500,000 March 31, 2005   $ 443,300,000 June 30, 2005   $
494,600,000 September 30, 2005   $ 549,000,000 December 31, 2005   $ 606,100,000
March 31, 2006   $ 564,900,000 June 30, 2006   $ 601,300,000 September 30, 2006
  $ 641,000,000 December 31, 2006   $ 681,400,000 March 31, 2007   $ 620,100,000
June 30, 2007   $ 652,900,000 September 30, 2007   $ 689,100,000 December 31,
2007   $ 725,800,000 March 31, 2008   $ 654,900,000 Thereafter   $ 654,900,000

        (b) Section 5.1(r)(vi) of the Credit Agreement is hereby deleted in its
entirety and replaced with the following:

Minimum Customers. The number of revenue generating customers of Holdings and
its Subsidiaries (treating each office location of a Person purchasing services
from Holdings or any Subsidiary to be a separate customer to the extent such
office locations are in separate buildings) as of the end

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of the monthly or quarterly period set forth below shall not be less than the
number listed opposite such period:

Monthly Period

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  Number

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March 31, 2002   392 April 30, 2002   498 May 31, 2002   614 June 30, 2002   745
July 31, 2002   920 August 31, 2002   1,107 September 30, 2002   1,311

Quarterly Period

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  Number

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December 31, 2002   N/A March 31, 2003   2,809 June 30, 2003   3,674 September
30, 2003   4,615 December 31, 2003   5,682 March 31, 2004   7,054 June 30, 2004
  8,322 September 30, 2004   9,578 December 31, 2004   10,806 March 31, 2005  
11,977 June 30, 2005   13,058 September 30, 2005   14,113 December 31, 2005  
15,174 March 31, 2006   16,245 June 30, 2006   17,326 September 30, 2006  
18,418 December 31, 2006   19,515 March 31, 2007   20,635 June 30, 2007   21,757
September 30, 2007   22,889 December 31, 2007   24,022 March 31, 2008   25,168
Thereafter   25,168

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        (c) Section 5.1(r)(vii) of the Credit Agreement is hereby deleted in its
entirety and replaced with the following:

Minimum Cash Reserves. On a consolidated basis, Holdings and its Subsidiaries
shall maintain as of the last day of each monthly or quarterly period, as
applicable, Minimum Cash Reserves not less than the amount listed opposite such
date below:

Date

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  Number

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March 31, 2002   $ 68,200,000 April 30, 2002   $ 55,800,000 May 31, 2002   $
42,000,000 June 30, 2002   $ 35,800,000 July 31, 2002   $ 30,700,000 August 31,
2002   $ 26,400,000 September 30, 2002   $ 22,400,000 December 31, 2002   $
35,000,000 March 31, 2003   $ 26,700,000 June 30, 2003   $ 17,900,000 September
30, 2003   $ 20,400,000 December 31, 2003   $ 26,300,000 March 31, 2004   $
42,300,000 June 30, 2004   $ 69,600,000 September 30, 2004   $ 112,000,000
December 31, 2004   $ 144,500,000 March 31, 2005   $ 164,600,000 June 30, 2005  
$ 171,300,000 September 30, 2005   $ 192,400,000 December 31, 2005   $
220,000,000 March 31, 2006   $ 233,500,000 June 30, 2006   $ 243,700,000
September 30, 2006   $ 257,400,000 December 31, 2006   $ 277,700,000 March 31,
2007   $ 299,400,000 June 30, 2007   $ 205,000,000 September 30, 2007   $
222,900,000 December 31, 2007   $ 244,700,000 Thereafter   $ 280,600,000

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        (d) Section 5.1(r)(viii) of the Credit Agreement is hereby deleted in
its entirety and replaced with the following:

Minimum Nodes on Net. The number of nodes connected to the network maintained by
Holdings and its Subsidiaries as of any date listed below shall not be less than
the number listed opposite such monthly or quarterly period set forth below:

Monthly Period

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  Number

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March 31, 2002   207 April 30, 2002   230 May 31, 2002   252 June 30, 2002   275
July 31, 2002   288 August 31, 2002   302 September 30, 2002   316

Quarterly Period

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Number

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December 31, 2002   N/A March 31, 2003   472 June 30, 2003   556 September 30,
2003   640 December 31, 2003   724 March 31, 2004   820 June 30, 2004   916
September 30, 2004   1,012 December 31, 2004   1,108 March 31, 2005   1,204 June
30, 2005   1,300 September 30, 2005   1,396 December 31, 2005   1,492 March 31,
2006   1,588 June 30, 2006   1,684 September 30, 2006   1,780 December 31, 2006
  1,876 March 31, 2007   1,972 June 30, 2007   2,068 September 30, 2007   2,164
December 31, 2007   2,260 March 31, 2008   2,356 Thereafter   2,356

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        (e) Section 5.1(r)(ix) and the text appearing thereafter but ending
immediately prior to Section 5.1(s) of the Credit Agreement is hereby deleted in
its entirety and replaced with the following:

Maximum Capital Expenditures. On a consolidated basis, Holdings and its
Subsidiaries shall not make any expenditures for fixed or capital assets on an
annual basis in excess of the amount listed below (determined as of the end of
the annual period set forth below):

Date

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  Annual Amount

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December 31, 2002   $ 82,000,000 December 31, 2003   $ 94,700,000 December 31,
2004   $ 108,300,000 December 31, 2005   $ 115,200,000 December 31, 2006   $
83,400,000 December 31, 2007   $ 77,600,000 Thereafter   $ 77,600,000

As used in this subsection (r), the following terms shall have the following
meanings: "Capitalization" means, on any date, the sum of (i) Consolidated
Funded Debt, and (ii) the sum of common and preferred equity, including without
duplication capital stock plus paid in capital of Holdings and its Subsidiaries
on such date, on a consolidated basis and as determined in accordance with,
GAAP; "Consolidated Funded Debt" means, as of any date of determination, all
Indebtedness of Holdings and its Subsidiaries on such date, on a consolidated
basis and as determined in accordance with GAAP; "revenue" or "total revenue"
means revenue net of adjustments, i.e. net revenue, as determined in accordance
with GAAP and, unless otherwise specified herein, which includes revenue
generated by assets that were acquired by Holdings and its Subsidiaries pursuant
to the Asset Purchase Transaction; "EBITDA" means, for any period with respect
to Holdings and its Subsidiaries, net income (excluding extraordinary items),
plus (except to the extent attributable to extraordinary items) the amount of
any interest, taxes, depreciation, amortization and other non-cash charges
deducted in determining such net income, all of the foregoing as determined on a
consolidated basis for Holdings and its Subsidiaries, determined in conformity
with GAAP; "Interest Expense" means, for any period with respect to Holdings and
its Subsidiaries, the amount of interest expense, both expensed and capitalized
(including the portion of any payments in respect of any capital leases
allocable to interest expense), on a consolidated basis, as determined in
accordance with GAAP, paid or payable during such period in respect of any
Indebtedness of Holdings and its Subsidiaries; and "Minimum Cash Reserves" means
unrestricted (i) cash, (ii) marketable, direct obligations of the United States
of America, its agencies and instrumentalities maturing within three hundred
sixty-five (365) days of the date of purchase, (iii) commercial paper issued by
corporations, each of which shall have a combined net worth of at least
$100,000,000 and each of which conducts a substantial part of its business in
the United States of America, maturing within two hundred seventy (270) days
from the date of the original issue thereof, and rated "P-1" or better by
Moody's Investors Service, Inc., or "A-1" or better by Standard and Poor's
Ratings Group, and (iv) repurchase agreements, bankers' acceptances, and
certificates of deposit maturing within three hundred sixty-five (365) days of
the date of purchase which are issued by, or time deposits maintained with, a
United States national bank the deposits of which are insured by the Federal
Deposit Insurance Corporation and having capital, surplus and undivided profits
totaling more than $100,000,000 and rated "A" or better by Moody's Investors
Service, Inc. or Standard and Poor's Ratings Group, of Borrower and its
wholly-owned Subsidiaries. Notwithstanding anything in this Section 5.1(r) to
the contrary, any Indebtedness or any Interest Expense thereon accruing or
becoming due during the Permitted Period resulting from Permitted Purchases
shall not be included by Holdings in determining compliance with the financial
covenants set forth in this Section 5.1(r). Notwithstanding any provision to the
contrary contained herein, if Holdings and its Subsidiaries fail to comply with
any

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of the financial covenants set forth in this Section 5.1(r) prior to the period
ending September 30, 2002, such non-compliance shall not constitute an Event of
Default hereunder, but neither Agent nor any other Lender shall have any
obligation to make any Loans to Borrower (other than Tranche X Loans (as defined
in the Schedule), which shall continue to be available to Borrower), until
Holdings and its Subsidiaries shall have complied with all of the monthly
financial covenants set forth in this Section 5.1(r) for a subsequent month
during the period prior to and including the period ending September 30, 2002.
On and after September 30, 2002, any non-compliance with any of the financial
covenants shall constitute an Event of Default hereunder. For clarity the
parties agree that the financial statements due pursuant to section 5.1(a) for
the fourth quarter of 2002 and the first quarter of 2003 are due no later than
March 31, 2003 and May 15, 2003, respectively.

        (f) Subsection (ii) of Section 1(a) of the Schedule to the Credit
Agreement is hereby deleted in its entirety and replaced with the following:

(A)    Up to $29,000,000 ("Tranche B1") shall be available from the Original
Closing Date to the Closing Date, and (B) up to $35,000,000, ("Tranche B3"),
shall be available from the first Banking Day following the Tranche 2
Availability Termination Date to the Tranche 3 Availability Termination Date as
follows:

(1)    up to $10,000,000 shall be available from the first Banking Day following
the Tranche 2 Availability Termination Date; (2) up to an additional $5,000,000
shall be available from the later of May 1, 2003 or the Banking Day following
the day upon which the required quarterly financial statements for the period
ending March 31, 2003 are submitted to Agent, (3) up to an additional $5,000,000
shall be available from the later of June 1, 2003 or the Banking Day following
the day upon which the required monthly financial statements for the period
ending April 30, 2003 are submitted to Agent, (4) up to an additional $5,000,000
shall be available from the later of July 1, 2003 or the Banking Day following
the day upon which the required monthly financial statements for the period
ending May 31, 2003 are submitted to Agent, (5) up to an additional $5,000,000
shall be available from the later of August 1, 2003 or the Banking Day following
the day upon which the required monthly financial statements for the period
ending June 30, 2003 are submitted to Agent, and (6) up to an additional
$5,000,000 shall be available from the later of September 1, 2003 or the Banking
Day following the day upon which the required monthly financial statements for
the period ending July 31, 2003 are submitted to Agent; and

        SECTION 3    Initial Tranche B3 Draw.    

Borrower's Notice of Borrowing dated November 6, 2002 and delivered herewith is
hereby deemed received and accepted by Agent in the amount of $10,000,000, which
amount shall be advanced by Lenders no later than two Banking Days following the
date upon which this amendment becomes effective pursuant to Section 4.

        SECTION 4    Effectiveness of this Amendment.    The amendments
contained in Section 2 shall upon the occurrence of the Closing Date become
effective as of September 30, 2002 and the acceptance by Agent of the Notice of
Borrowing as set forth in Section 3 shall become effective on the date on which
the following conditions shall have been satisfied (the "Closing Date"),
provided, in each case, that the Closing Date shall have occurred on or prior to
November 12, 2002:

        (a) Each party hereto shall have executed and delivered to Agent a
counterpart of this Amendment.

        (b) There shall be no Default or Event of Default continuing as of the
Closing Date under the Credit Agreement (as amended hereby).

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        (c) Borrower shall have delivered to Agent a legal opinion of Friedman
Kaplan Seiler & Adelman dated the Closing Date, in substantially the form
attached hereto as Exhibit A.

If the Closing Date has not occurred on or before the close of business on
November 12, 2002 this Amendment shall terminate without further action by any
party and shall be null and void and of no further force or effect and
thereafter the amendments set forth herein will not become effective even if the
conditions set forth above are satisfied at a subsequent date.

        SECTION 5    General Representations and Warranties.    Each of
Borrower, Holdings and Additional Borrower hereby represents and warrants to
Agent that each of the representations and warranties of such party contained in
the Credit Agreement (as amended hereby) are true and correct in all material
respects as of the date hereof and Agent shall be entitled to rely on such
representations and warranties as if they were made to Agent in this Amendment
as of the date hereof.

        SECTION 6    Miscellaneous.    

        (a)    Credit Agreement Otherwise Not Affected.    Except as expressly
amended pursuant hereto, the Credit Agreement shall remain unchanged and in full
force and effect and is hereby ratified and confirmed in all respects. Agent's
execution and delivery of, or acceptance of, this Amendment and any other
documents and instruments in connection herewith (collectively, the "Amendment
Documents") shall not be deemed to create a course of dealing or otherwise
create any express or implied duty by it to provide any other or further
amendments, consents or waivers in the future.

        (b)    No Reliance.    Borrower hereby acknowledges and confirms to
Agent that Borrower is executing this Amendment and the other Amendment
Documents on the basis of its own investigation and for its own reasons without
reliance upon any agreement, representation, understanding or communication by
or on behalf of any other Person.

        (c)    Costs and Expenses.    Borrower agrees to pay to Agent on demand
the reasonable out-of-pocket costs and expenses of Agent, and the reasonable
fees and disbursements of counsel to Lender, in connection with the negotiation,
preparation, execution and delivery of this Amendment and any other documents to
be delivered in connection herewith.

        (d)    Binding Effect.    This Amendment shall be binding upon, inure to
the benefit of and be enforceable by Borrower, Agent, Additional Borrower,
Holdings and their respective successors and assigns.

        (e)    Governing Law.    This Agreement shall be governed by, and
construed in accordance with, the law of the State of New York.

        (f)    Complete Agreement; Amendments.    This Amendment, together with
the other Amendment Documents and the other Loan Documents, contains the entire
and exclusive agreement of the parties hereto and thereto with reference to the
matters discussed herein and therein. This Amendment supersedes all prior
commitments, drafts, communications, discussions and understandings, oral or
written, with respect thereto. This Amendment may not be modified, amended or
otherwise altered except in accordance with the terms of Section 8.1 of the
Credit Agreement.

        (g)    Severability.    Whenever possible, each provision of this
Amendment shall be interpreted in such manner as to be effective and valid under
all applicable laws and regulations. If, however, any provision of this
Amendment shall be prohibited by or invalid under any such law or regulation in
any jurisdiction, it shall, as to such jurisdiction, be deemed modified to
conform to the minimum requirements of such law or regulation, or, if for any
reason it is not deemed so modified, it shall be ineffective and invalid only to
the extent of such prohibition or invalidity without affecting the remaining
provisions of this Amendment, or the validity or effectiveness of such provision
in any other jurisdiction.

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        (h)    Counterparts.    This Amendment may be executed in any number of
counterparts and by different parties hereto in separate counterparts, each of
which when so executed shall be deemed to be an original and all of which taken
together shall constitute but one and the same agreement.

        (i)    Interpretation.    This Amendment and the other Amendment
Documents are the result of negotiations between and have been reviewed by
counsel to Agent, Borrower and other parties, and are the product of all parties
hereto. Accordingly, this Amendment and the other Amendment Documents shall not
be construed against Agent or any Lender merely because of Agent's involvement
in the preparation thereof.

        (j)    Loan Documents.    This Amendment and the other Amendment
Documents shall constitute Loan Documents.

[Remainder of page intentionally left blank.]

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        IN WITNESS WHEREOF, the parties hereto have duly executed this
Amendment, as of the date first above written.

 
Cogent Communications, Inc.
 
 
    By /s/  DAVE SCHAEFFER      

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Name:
Title:  Chief Executive Officer
 
 
    Cogent Communications Group, Inc.
 
 
    By /s/  DAVE SCHAEFFER      

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Name:
Title:  Chief Executive Officer
 
 
    Cogent Internet, Inc.
 
 
    By /s/  DAVE SCHAEFFER      

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Name:
Title:  Chief Executive Officer
 
 
    Cisco Systems Capital Corporation
 
 
    By /s/  DAVID A. ROGAN      

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Name:  David A. Rogan
Title:    President, Cisco Capital

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Exhibit A
to Amendment No. 4

Form of Legal Opinion

See attached.

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QuickLinks

EXHIBIT 10.2

AMENDMENT NO. 4 TO SECOND AMENDED AND RESTATED CREDIT AGREEMENT

Exhibit A to Amendment No. 4

Form of Legal Opinion