Resolved! help,there is a strange thing of pix!
the diagram please see www.ciscofan.com/smbc.jpgnow,the ebs router has a NM-1CE1U&NM-30DM,then remote clients can dial in the network,the pboc router has a wic-2t module,connect to remote side via DDN.the ebs interface's ip address of pix is x.x.45.2...