Many working in small libraries, museums, archives, and historical societies have been actively engaged in creating digital collections, but often these collections are not being digitized to standards, are presented to users via a web page and are not preserved in any meaningful manner. How do the people in these scenarios discover that there is a problem before they lose content and more impo...

We derive a closed-form expression for the message collision probability in the IEEE 802.3ah Ethernet Passive Optical Network (EPON) registration scheme. The expression obtained, although based on an approximation, shows a good match with simulation results. We use the results of our analysis to compute the size of the most efficient contention window and the most efficient number of nodes serv...

Network tomography refers to the inference of characteristics of internal links in a network using end-to-end measurements. The link characteristics of interest include packet loss rate, delay, and bandwidth; here we focus on loss rate. Depending only on end-to-end measurements is convenient in the context of the Internet because network operators such as ISPs offer limited visibility into the ...

This paper describes the design and implementation of a passive scanner for Modbus networks. The tool integrates packet parsing and passive scanning functionality to interpret Modbus transactions and provide accurate network representations. In particular, the scanner monitors Modbus messages to maintain and update state table entries associated with field devices. Entries in the state tables r...

Traditionally the routing in passive optical networks is based on an embedded regular virtual topology. However one important fact that has been neglected in the past is that the wavelength assignment to transceivers actually creates additional (logical) links not present in the virtual topology. Such side e ect can be utilized to signi cantly reduce the number of hops between a pair of station...

Packet-oriented PONs will offer an efficient way to transfer IP traffic, providing at the same time flexible Quality of Service mechanisms to support a great variety of services. To allow provisioning of connections from customer sites to ISP sub-networks across packet-based PONs, it is necessary to correlate the Ethernet MAC address used in the customer terminals to the ISP interfaces and the ...

We consider the security of an ITU standard for ATM-based passive optical networks. First, we show that the standard’s encryption algorithm, called churning, has an effective 8-bit key length and thus is trivial to break with exhaustive keysearch. Second, we show that the authentication mechanisms have significant weaknesses. The conclusion is that these measures should not be relied upon to pr...

A constructive method is presented in which L2 -stability can be guaranteed for networked control of multiple passive plants in spite of random time varying delays and data dropouts. The passive plants are interfaced to a wave variable based passive sampler (PS) and passive hold (PH) which allows a passive digital control network to be constructed. A power junction is used to facilitate the int...

The aim of this study was to investigate intra-regional activation and inter-regional connectivity during passive movement. During fMRI, a mechanic device was used to move the subject's index and middle fingers. We assessed four movement conditions (unimanual left/right, bimanual symmetric/asymmetric), plus Rest. A conventional intra-regional analysis identified the passive stimulation network,...

With the continuous increase in bandwidth demand generated by consumer and business applications, a new higher capacity access network is required. Today, with the development of electronic media and its usage most of the networks having more number of nodes and as the number of nodes increases in the network the communication over the network also increases. A reliable end packet delivery is t...