he future: mesh long-haul and rings SEATTLE in a metropolitan area network (MAN). Rings Rings BOSTON Metro Metro Metro Metro Access Access SAN JOSE Rings Rings NEW YORK 7.1.1 Advantages of ION Proponents of ION see networks evolving in the next two to five years with the following characteristics:2 IP over optics Wave-switched mesh networks Switching and managing lightpaths under software control Fast provisioning Millisecond protection and restoration New services, such as new lightpath services, protection on a service level agreement (SLA) metric, value-added optical VPNs (OVPNs), and SO on The motivations for ION include cost-effectiveness, flexibility, and new revenue possibilities. Advocates view ION as a system for bandwidth cre- ation, distribution, and management, with optics being the only physical Chapter 7 layer of the network. Whereas DWDM as a technology provides the equiv- alent of fiber multiplication and moves waves over distances, ION is a sys- tem for delivering services over waves. Namely, it moves waves over distances, it maps services onto waves, and it provisions, switches, and man- ages lightpaths. Switching lightpaths is cheaper than switching individual packets, particularly as the transactions (flows) get larger (longer). The ION design eliminates O-E-O conversions and simplifies the network architec- ture and the supportive infrastructure. From a flexibility standpoint, if ION were deployed, it would enable just-in-time provisioning of end-to-end light- paths operating at OC-48, OC-192, or OC-768 speeds. (In this context, end- to-end means core network element [NE] to core NE if the technology is only deployed in the core or edge NE to edge NE if the technology is de- ployed across the entire network.) Traffic engineering would be done at the lightpath level. New revenue opportunities could arise from the fast provi- sioning of wave services. ION, however, also needs to support traditional private lines (for exam- ple, Frame Relay services and T1 lines currently represent the staple of