Not much of a surprise, the Avaya business has been doing OK but the company has a large about of debt that is dragging it down. Chapter 11 likely to allow restructuring of debt and plan a path forward.
Its possible that the business could be broken up or pieces sold off to pay down debt but the lack of buyers for Brocade (either whole or in part) suggests that is unlikely for networking. Other parts of Avaya might be sold off
Link: Avaya Inc. Files for Chapter 11 Protection – http://www.avaya.com/en/about-avaya/newsroom/news-releases/2017/pr-us-170119a/
Customer FAQ: http://www.avaya.com/en/documents/filing-faqs.pdf has more info:
As a result of the terms of Avaya’s debt obligations and the upcoming debt maturities, we need to recapitalize the Company and believe the restructuring process is the best path forward at this time. Our businesses are healthy and performing well, and we are executing at a high level.