One other point about the AIPs relative to the HSSI/DSU ; you may not be interested in this feature , but the AIPs implement traffic shaping- ie You can set Peak and Average rates and burst size; you could use this to subrate your traffic -should you be in a situation where this is desirable. I havent looked around to check out any new ADSU type products since mid 95, but it used to be that you could not do this with an ADSU. Padma Krishnaswamy