SDH
Synchronous Digital Hierarchy (SDH) is standardized multiplexing protocols that transfer multiple digital bit streams over optical fiber. SDH originally designed to transport circuit mode communications. Capacities of SDH range from STM-1, STM-4, STM-16 to STM-64 (STM1 = 63 E1).
F@H has nationwide SDH network that is serving TDM traffic as per requirements. Most of the Telecom Backbone network is running through F@H’s SDH network. The network capacity is increasing day by day with the increasing demand of bandwidth of the Telecom/ANS operators it is being upgraded / already upgraded at some sectors to 100Gbps DWDM network and SDH will run on-top of it.
Metro Ethernet network is a metropolitan area network (MAN) that is based on Ethernet standards. It is commonly used to connect subscribers to a larger service network or the Internet. Businesses can also use metropolitan-area Ethernet to connect their own offices to each other.
An Ethernet interface is much cheaper than a SONET/SDH or PDH interface of the same bandwidth. Another distinct advantage of an Ethernet-based access network is that it can be easily connected to the customer network, due to the prevalent use of Ethernet in corporate and, more recently, residential networks. A typical service provider's network is a collection of switches and routers connected through optical fiber. The topology could be a ring, hub-and-spoke (star), or full or partial mesh. The network will also have a hierarchy: core, distribution (aggregation), and access. The core in most cases is an existing IP/MPLS backbone but may migrate to newer forms of Ethernet transport in the form of 10Gbit/s, 40Gbit/s, or 100Gbit/s speeds or even possibly 400Gbit/s to Terabit Ethernet network in the future.
Ethernet on the MAN can be used as pure Ethernet, Ethernet over SDH, Ethernet over MPLS, or Ethernet over DWDM. Pure Ethernet-based deployments are cheaper but less reliable and scalable and thus are usually limited to small scale or experimental deployments. SDH-based deployments are useful when there is an existing SDH infrastructure already in place, its main shortcoming being the loss of flexibility in bandwidth management due to the rigid hierarchy imposed by the SDH network. MPLS-based deployments are costly but highly reliable and scalable and are typically used by large service providers.
Metro Ethernet network has been deployed by Fiber@Home from its commercial operation. Now F@H has more than 5K metro Ethernet links of multiple clients. It is MPLS based Metro Ethernet where client has huge flexibility to design and operate their network within their network level resources link IP and VLAN. Presently F@H has 10Gbps Metro Ethernet Network within Dhaka Metro and 2.5Gbps SDH based Metro Ethernet Network all over the nation. Within 2013 F@H will upgrade its network at 100Gbps through DWDM.
