We consider schemes for protecting a network using a Wavelength Division Multiplexing (WDM) infrastructure against component or link failures. First, we explain how protection can be achieved by hardware redundancy. Then, we consider that with WDM networks, the failure of a single link or component may cause the simultaneous failure of several optical channels, potentially making impossible the restoration by rerouting in higher layers (SDH, ATM, IP). To address this, we introduce the concept of Design Protection, which aims at making such failure propagations impossible. We present the Disjoint Alternate Path (DAP) algorithm which places optical channels in order to maximise design protection. We show the result on the example of the ARPA-2 network. Keywords: WDM, photonic, resilience, routing, tabu search. Copyright 1997 IEEE. Published in the Proceedings of INFOCOM'97, April 7-11, 1997 in Kobe, Japan. Personal use of this material is permitted. However, permission to reprint/repu..