Exhibit 3.177

STATE OF DELAWARE

SECRETARY OF STATE

DIVISION OF CORPORATIONS

FILED 09:00 AM 12/06/2000

001610843 – 3325801

CERTIFICATE OF FORMATION

OF

CHARTER FIBERLINK - ILLINOIS, LLC

1. The name of the limited liability company is CHARTER FIBERLINK - ILLINOIS, LLC.

2. The address of its registered office in the State of Delaware is 30 Old Rudnick Lane, in the City of Dover, County of Kent. The name of its registered agent at such address is CorpAmerica, Inc.

IN WITNESS WHEREOF, the undersigned has executed this Certificate of Formation of CHARTER FIBERLINK - ILLINOIS, LLC this 6^th day of December, 2000.

/s/ Brenda L. White

Brenda L. White, Authorized Person

STATE OF DELAWARE

SECRETARY OF STATE

DIVISION OF CORPORATIONS

FILED 01:00 PM 12/17/2002

020775762 – 3325801

Certificate of Amendment to Certificate of Formation

of

CHARTER FIBERLINK - ILLINOIS, LLC

It is hereby certified that:

1. The name of the limited liability company (hereinafter called the “limited liability company”) is CHARTER FIBERLINK - ILLINOIS, LLC.

2. The certificate of formation of the limited liability company is hereby amended by striking out the statement relating to the limited liability company’s registered agent and registered office and by substituting in lieu thereof the following new statement:

“The address of the registered office and the name and the address of the registered agent of the limited liability company required to be maintained by Section 18-104 of the Delaware Limited Liability Company Act are Corporation Service Company, 2711 Centerville Road, Suite 400, Wilmington, DE 19808.”

Executed on 12/12/02

/s/ Marcy A. Lifton

Marcy A. Lifton, Authorized Person

DELL D-: CERTIFICATE OF AMENDMENT TO CHANGE REGISTERED AGENT/REGISTERED OFFICE 09/00 (DELLCCHG)