written by olumide kuforiji

Code 128 (a.k.a ANSI/AIM 128, ANSI/AIM Code 128, USS Code 128) is a high-density, alphanumeric linear barcode symbology that has been widely adopted by many industry applications. Code 128 is a variable length, continuous symbology with multiple element widths.
ASP.NET Code 128 Barcode Generator DLL is an ASP.NET barcode generation control that enables .NET developers to create, manage and manipulate Code-128 barcodes in ASP.NET Web Forms, ASP.NET Web Server as well as in Internet Information Service (IIS).
With ASP.NET Code 128 Barcode Generator, users may easily customize their own Code 128 barcodes through multiple barcode size, image, and human-readable text related options. Meanwhile, all generated Code 128 barcodes are compatible with all the web browsers, including IE, Firefox, Chrome, Opera, Safari, etc.

This document provides a comprehensive user manual on Code 128 barcode generation in ASP.NET. If you want know more, please go to user manual for Code 128 data encoding, user manual for Code 128 image setting, and user manual for Code 128 size setting.

yeah,code 128 asp.net control Written completely in the managed Visual C#.NET, strong-named & time-stamped for security;
Compatible with major browsers like Chrome, Internet Explorer, Mozilla, Opera, etc;
Stream 1D Code 128A, Code 128B, Code 128C barcode images in ASP.NET websites/ webforms/ web service...

i've ever generated code 128 barcode in winforms,but as for you said about asp.net,you may check this guide for barcode in asp.net

I goole the answer and find you can use ASP.NET Code 128 Generator to generate Code 128 in ASP.NET Library.