OFDM (Orthogonal Frequency Division Multiplexing)

OFDM is a multicarrier transmission technique that has been around for years, but only recently  became popular due to the development of digital signal processors (DSPs) that can handle its heavy digital processing requirements. OFDM is being implemented in broadband wireless Access systems as a way to overcome wireless transmission problems and to improve bandwidth. OFDM is also used in wireless LANs as specified by the IEEE 802.11a and the ETSI HiperLAN/ 2standards. It is also used for wireless digital radio and TV transmissions, particularly in Europe.

Optical Networks

An optical network is a network in which the physical layer technology is fiber-optic cable. Cable trunks are interconnected with optical cross-connects (OXCs), and signals are added and dropped at optical add/drop multiplexers (OADMs). The holy grail is an all-optical network. In this scheme, an optical wavelength (which acts like a data circuit) stays in the optical realm from end to end. 

OSI (Open Systems Interconnection) Model  

The ISO (International Organization for Standardization) is a worldwide federation that promotes  international standards. In the early 1980s, it began work on a set of protocols that would promote  open networking environments that would let multivendor computer systems communicate With one another using internationally accepted communication protocols .It eventually developed the OSI reference model. OSI was once considered to be the ultimate protocol  for worldwide interoperability. However, it failed at gaining widespread acceptance and is now  referred to mostly as a model against which other protocols are compared. One of the reasons OSI did not take off is because it was a complete set of specifications that was never subjected to any real implementations worth mentioning.

OSPF (Open Shortest Path First) Routing  

Short for Open Shortest Path First, OSPF is an interior gateway routing protocol developed for IP networks based on the shortest path first rule. Routers use the shortest path first rule to send routing information to all the points in a network by calculating the shortest path to each node. Each router  sends information about the routing map in the network and routing table (keeps track of routes to particular network destinations) that describes the state of its own links. The advantage of shortest path first algorithms is that they results in smaller more frequent updates everywhere. They converge quickly, thus preventing such problems as routing loops and Count-to-Infinity (when routers continuously increment the hop count to a particular network). This makes for a stable network. The disadvantage of shortest path first algorithms is that they require a lot of CPU power and memory. In the end, the advantages outweigh the disadvantages.

OSRP (Optical Signaling & Routing Protocol)

OSRP is an optical routing protocol similar to PNNI (Private Network-to-Network Interface) and MPLS (Multiprotocol Label Switching), which was developed for ATM networks. Through OSRP, switches can exchange information about the network and the status of switches and  links. OSRP works in an environment of switches that handles multiple wavelengths of light as circuits, automatically provisioning entire wavelengths or fractions of wavelengths available on a fast-switched basis. An alternative optical routing protocol is FSPF (Fabric Shortest Path First), which was developed by Brocade.