Novel hardware architecture for fast address lookups

Mehrotra, P.; Franzon, Paul D.

doi:10.1109/hpsr.2002.1024217

Cited by 2 publications

(2 citation statements)

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“…For example, for a stream of short, 40-byte packets (320 bits/packet) at 40 Gb/s, the packet rate is only 125 MHz. The mathematical function describing the tapped-delay-line correlator is (1) where is the number of bits in the correlation sequence, is one bit period, is the input signal delayed by bit times, and represents the weights that multiply each of the -bit delayed input signals. For a phase-modulated system, the same operation is performed by replacing the switches with the appropriate optical phase-shifters to match the desired bit pattern (e.g., "…”

Section: A Optical Tapped-delay-line Correlatorsmentioning

confidence: 99%

“…Given that a significant portion of Internet packets entering routers are short, 40-byte TCP/IP acknowledgement packets, nanosecond lookup times are needed to achieve the desired terabit/second throughput. Some efforts are being made to improve electronic hardware architectures and search algorithms to reduce lookup times [1], but the ideal case would be for the packet headers to be processed on-the-fly using optical signal-processing techniques, so that the only limitation to throughput is the speed of the optical switch (currently a few nanoseconds). A true all-optical router would therefore need to be capable of 24-bit lookups into 100 000-entry tables at Gb/s (since only 24 of the 32 address bits are generally significant for packet-forwarding in the network core).…”

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confidence: 99%

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Optically assisted internet routing using arrays of novel dynamically reconfigurable FBG-based correlators

Hauer

McGeehan

Kumar

et al. 2003

J. Lightwave Technol.

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As routing tables in core Internet routers grow to exceed 100 000 entries, it is becoming essential to develop methods to reduce the lookup time required to forward packets toward their destinations. In this paper, we employ a bank of novel thermally tuned fiber-Bragg-grating-based optical correlators to construct an "optical bypass" to accelerate conventional electronic Internet routers. The correlators are configured as a routing table cache that can quickly determine the destination port for a fraction of the incoming traffic by examining only a subset of the bits in an IP packet's 32-bit destination address.We also demonstrate a novel multiwavelength correlator based on fiber Bragg grating that can simultaneously recognize the header bits on multiple wavelengths for use in wavelength-division-multiplexed (WDM) systems. Using the optical bypass, routing table lookup times are reduced by an order of magnitude from microseconds to nanoseconds and are limited only by the speed of the optical switch. Index Terms-Optical communications, optical correlators, optical signal processing, wavelength-division-multiplexed (WDM) networks. I. INTRODUCTION I N present-day fiber-optic networks, data packets are converted to electrical form at each node to process their headers and make routing decisions, as shown in Fig. 1(a). As routing tables grow in size, more memory accesses are required to determine the next-hop address and appropriate output port to which to forward each packet. The associated increase in routing-table lookup times is becoming a significant source of latency in the network core. To make matters worse, the transmission capacity of optical fibers is rapidly increasing, forcing the routers to accommodate more packets, more often. Since routing tables will Manuscript

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Section: A Optical Tapped-delay-line Correlatorsmentioning

confidence: 99%

mentioning

confidence: 99%