point of packet aggregation as traffic enters the network, and they also provide grooming; that is, switching direction according to service. They are widely deployed for business and mobile networks [19]. 7.4.1.7 OTN OTN (Optical Transport Network) emergence is primarily driven by the growth of Ethernet and other packet based services, as well as deployment of next generation networks (LTE, WiMAX). OTN is defined by ITU-T and the relevant recommendation is G.709 [20]. Today, it is primarily offered at three rates and the fourth is under development: OTU1 as 2.7 Gbps (STM-16) OTU2 as 10.7 Gbps (STM-64) OTU3 as 43 Gbps (STM-256) OTU4 as 112 Gbps is under development and it is expected to be standardized in 2010. Next Generation Mobile Communications Ecosystem OTN is intended to take over from NG-SDH for packet transport on TDM. It gives a range of optical interfaces at speeds beyond SDH, in a format to contain TDM and Ethernet packet traffic. In contrast to SDH, OTN does not need synchronization by a central clock but it also extends SDH-like operations and fault management capabilities to data protocols. 7.4.1.8 Advancements in Optical Technologies 7.4.1.8.1 Control Plane ASON In a mesh, multiple paths exist for restoration and can be selected automatically by a transport control plane. For the architecture of this plane, ITU-T G.807 and G.8080 describe automatic switched trans- port/optical network (ASTN/ASON). These use the generalized MPLS protocol suite (GMPLS) which was developed from the control plane of IP/MPLS. Based on these origins, the transport control plane is commonly referred to as ASON or occasionally as GMPLS or ASTN. ASON improves several network aspects [19]: Restoration (maximizes availability via multiple alternative paths in a mesh) Provisioning (lower OPEX for setting up paths through multiple nodes) Resource management (automated discovery of topology and resources, as in IP routers, to minimize data entry errors). ASON supports multiple network-sharing algorithms, allowing leased (or "col