I have a topology such as two MX-250 in warmspare mode as my Layer3 core and I have two MS 425-16 connected to MX for providing uplinks to my access switches. I want to know whether I can configure warmspare between two MS 425-16 without configuring Layer3 in it. Since my access switches have dual uplinks and connected one to each MS-425, do I need to aggregate them while changing into warmspare?