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Multihop networks with store-and-forward nodes were recently proposed and studied as possible architectures for realizing the vast capacity potential of multi-user lightwave networks subject to electro-optic speed constraints imposed at each access node. In this paper, we analytically determine the achievable aggregate capacity for a variant of the basic multihop approach in which minimum distance storeand-forward routing is replaced by a "hot-potato" routing algorithm. With hot-potato routing, all packets simultaneously arriving at a given node and not intended for reception at that node are immediately placed onto the outbound links leaving that node ; if two or more packets contend for the same outgoing link to achieve minimum distance routing, then all but one will be misrouted to links which produce longer paths to the eventual destination. Our interest in studying such a scheme arises from the potential of optical pulse generation techniques to permit the formation of optical packets at data rates too high to permit electro-optic conversion, electronic packet routing, and store-and-forward buffering at each node. While not avoiding the electro-optic bottleneck for network access, each optical link would operate at a super-electronic data rate and contain time multiplexed packets from a multitude of sources.We confine our attention to the development of an analytical methodology for finding the probability distribution of the number of hops with hot potato routing for symmetric networks under uniform traffic load. From this, the expected number of hops and the aggregate network capacity can be found. Results show that the maximum throughput achievable with hot-potato routing can be as low as 25% of that for store-and-forward routing, and that the relative degradation increases as the number of nodes grows larger. This implies that the link speed-up needed to produce a significant overall capacity advantage with hot potato should be at least a factor of 10. The analytical methodology and results are quite general and applicability is not limited to lightwave networks. I N T R O D U C T I 0 NBy virtue of its low-loss low-dispersion properties, single mode fiber has emerged as the technology of choice for point to point communication systems, and multigigabit per second data rates have been achieved on such transmission links [l]. However, even these impressive accomplishments exploit only a small fraction of the capacity inherent in the single mode optical fiber passband (the low-loss usable portion of the spectrum between 1.1 and 1.5 microns has a bandwidth measured in tens of terahertz). Accordingly, attention has begun to focus on multiuser distributed lightwave networks which tap into this vast bandwidth reservoir, providing an enormous capacity to be shared among the many users of such a network [2]-(41. This high capacity, coupled with the ability to integrate voice, data, image, and full motion video traffic on high speed, self-routing packet streams, invites a plethora of new broadband services and app...

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Wireless Communication is an inevitable part of Smart Home domain. A Mobile Ad-Hoc Network (MANET) is defined as an arrangement of wireless mobile nodes which creates a temporary network for the communication. MANET suffers from both kinds of attacks, active and passive attacks at all the layers of the network model. The lacks of security measures of routing protocols allow attackers to intrude the network. Wormhole, the attack is generated by tunnels creation and it results in complete disruption of routing paths on MANET. The proposed security approach is to detect and mitigate wormhole attack. It is secured AODV approach which efficiently finds wormhole attack present in a MANET and Digital signature is used to prevent it. This approach is based on a calculation of tunneling time taken by tunnel to analyze the behavior of wormhole. Afterward, it decides some static threshold value. Based upon this tunneling time and threshold value, it decides whether given node is wormhole node or trustworthy node. A digital signature and hash chain algorithm is applied to mitigate the wormhole node.