User:Scalable

EXata Network Emulation Software

New wireless networks are being designed with a wide variety of goals in mind, such as improving worker productivity, delivering mission-critical information to troops in combat, or just enhancing mobile lifestyles. Wireless networks require different capabilities than their wired counterparts, such as specialized middleware, service- oriented architectures, net-centric services, and mobile on-the-go applications. Unfortunately, these technologies haven’t yet reached the level of maturity needed to support the demands of the wireless users of tomorrow. To ready network infrastructure for next generation wireless, new technologies must go through extensive and costly design, testing, analysis and evaluation. This process is prohibitively expensive both in terms of equipment and personnel resources, as well as time investment.

Emulation serves two purposes: • Reduce the cost of equipment • Speed the process of testing, evaluation and integration of new technologies, speeding time to market

To greatly streamline and reduce the cost of rolling out new wireless technologies, emulation provides an exact digital replica of a real network or part thereof. Emu- lations using EXata software allow for the whole or a part of a real network to be replaced by a counterpart representation in software form. EXata is a faithful repre- sentation of the system being replaced, and interfaces seamlessly with the rest of the system, even for the most complex of networks.

Emulation is the use of a software stand-in for real network components. Until now, there has been no efﬁcient, scalable, and low cost method for design and analysis of mobile wireless network systems. Emulation provides the same functionality as physical testbeds at a lower cost, while being easier to operate. There are a number of tools on the market that claim to be network emulators. In this white paper, we will explain why EXata is the only tool capable of acting as an exact digital replica of a network. Strictly speaking, an emulated network shares the follow- ing with the real network it replaces:

Same Behavior / Logic When an emulated and real network exhibit the same behavior or logic, a real router, for instance, can’t discern between emulated network nodes and real ones. To achieve this, the protocol stacks and signal waveforms must be identical. Also, the channel environment, such as pathloss, fading, modulation, etc., must affect the wireless signal in the same way it does the physical environment. Finally, middle- ware, network-centric services and applications in an emulated environment must be equivalent to the real network systems.

Same Interaction / Language Same interaction means the response from an emulated network has the correct content, or language, including byte order, packet contents, packet headers, etc.  An exact digital replica will allow the real network to interact with it on whatever layer of the protocol stack is called for. In other words, emulators must support cross-layer technologies.

Achieving same interaction means packets and headers are in the correct format (in- cluding byte and bitﬁeld ordering). Protocol model logic must also be fully represent- ed so that packets are issued identically to those generated by a physical network,. Another requirement for same interaction is that the emulated network accept packets from, and transmits packets to, the physical hardware so that the physical network cannot discern if it is communicating with a EXata node or another piece of real hardware.

Same Response / Timing Response time is critical in emulation. In order to respond like a physical network, the emulation must process network events no slower than real time. EXata’s discrete event simulation engine is uniquely designed for parallel computing environments to achieve real-time On the other hand, the emulation must process network events no faster than real time. The concept of timing synchronization granularity means that the emulation must represent packets and time at a level ﬁ ne enough to perfectly synchronize with the external world.

''1. For more details on achieving speedup and scalability through parallel computing platforms, download the SNT publication entitled “Parallel Execution White Paper” at http://www.scalable-networks.com/publications/ whitepapers.php.''

EXata Best of Breed Network Emulator To achieve the experiential requirements described earlier, an emulation must fulﬁll the following technical requirements : • Highest ﬁdelity models for both the protocol stack and the wireless channel environment • Highest ﬁdelity interfaces between the real system components and emulated ones • Real time constrained execution

Beneﬁts Associated with Emulator Technical Requirements EXata can accommodate highest ﬁdelity in both protocols and interfaces while still operating in real-time Not until now has it been possible to weave and integrate real protocol model code and real applications seamlessly into the emulation environment.

EXata supports the same behavior, interaction, and response. A software or hard- ware system developed or evaluated in EXata is guaranteed to plug into a real network without a hitch. This is because the code that runs in EXata can also be migrated into the deployment environment. That means that no additional man-hours are needed to rebuild a prototype system in EXata so that it can run in a real net- work. There is a wide range of ways an emulation can interact with the outside world, including: • Human-in-the loop, where humans watch and manipulate an emulated network, • Software-in-the-loop, such as with a Semi-Automated Forces (SAF) application such as VR-Forces 2 instructing how the emulated network components move, • Hardware-in-the-loop, such as a prototype radio interacting with a ﬂeet of perfect digital replicas of themselves in EXata, and • Application-in-the-loop, where for instance, legacy applications and applications currently under development are evaluated together over a network provided by EXata.