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CMS Note
Report number	CMS-CR-2007-016
Title	CMS DAQ Event Builder Based on Gigabit Ethernet
Author(s)	Bauer, G (MIT) ; Boyer, V (CERN) ; Branson, J (UC, San Diego) ; Brett, A (CERN) ; Cano, E (CERN) ; Carboni, A (CERN) ; Ciganek, M (CERN) ; Cittolin, S (CERN) ; Erhan, S (CERN ; UCLA) ; Gigi, D (CERN) ; Glege, F (CERN) ; Gómez-Reino, Robert (CERN) ; Gulmini, M (INFN, Legnaro ; CERN) ; Gutiérrez-Mlot, E (CERN) ; Gutleber, J (CERN) ; Jacobs, C (CERN) ; Kim, J C (Kyungpook Natl. U.) ; Klute, M (MIT) ; Lipeles, E (UC, San Diego) ; Lopez-Perez, Juan Antonio (CERN) ; Maron, G (INFN, Legnaro) ; Meijers, F (CERN) ; Meschi, E (CERN) ; Moser, R (CERN ; Vienna, Tech. U.) ; Murray, S (Fermilab) ; Oh, A (CERN) ; Orsini, L (CERN) ; Paus, C (MIT) ; Petrucci, A (INFN, Legnaro) ; Pieri, M (UC, San Diego) ; Pollet, L (CERN) ; Rácz, A (CERN) ; Sakulin, H (CERN) ; Sani, M (UC, San Diego) ; Schieferdecker, P (CERN) ; Schwick, C (CERN) ; Sumorok, K (MIT) ; Suzuki, I (Fermilab) ; Tsirigkas, D (CERN) ; Varela, J (LIP, Lisbon ; CERN)
Affiliation	(CERN) ; (Fermilab) ; (INFN Legarno, Italy) ; (Kyungpook National Univ., South Korea) ; (LIP, Lisbon, Portugal) ; (Massachusetts Inst. Technol., Cambridge, MA, USA) ; (UCLA) ; (Univ. California, San Diego, CA, USA) ; (Vienna, Tech. U.)
Submitted to	15th IEEE Real Time Conference 2007, Fermilab, Batavia, IL, USA, 29 Apr - 4 May 2007
Submitted by	15 May 2007
Subject category	Detectors and Experimental Techniques
Accelerator/Facility, Experiment	CERN LHC ; CMS
Free keywords	ACQUISITION
Abstract	The CMS Data Acquisition System is designed to build and filter events originating from 476 detector data sources at a maximum trigger rate of 100 KHz. Different architectures and switch technologies have been evaluated to accomplish this purpose. Events will be built in two stages: the first stage will be a set of event builders called FED Builders. These will be based on Myrinet technology and will pre-assemble groups of about 8 data sources. The second stage will be a set of event builders called Readout Builders. These will perform the building of full events. A single Readout Builder will build events from 72 sources of 16 KB fragments at a rate of 12.5 KHz. In this paper we present the design of a Readout Builder based on TCP/IP over Gigabit Ethernet and the optimization that was required to achieve the design throughput. This optimization includes architecture of the Readout Builder, the setup of TCP/IP, and hardware selection.
Copyright/License	Preprint: (License: CC-BY-4.0)

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