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| | Data link layer - Wikipedia, the free encyclopedia |
 | | The data link layer is often implemented in software as a "network card driver". | | | That transfer might or might not be reliable; many data link protocols do not have acknowledgments of successful frame reception and acceptance, and some data link protocols might not even have any form of checksum to check for transmission errors. | | | The data link is all about getting information from one place to a selection of other places. |
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http://en.wikipedia.org/wiki/Data_link_layer
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| | NOAAPORT Data Link Layer Protocol |
| | The NBS encodes the data using nonreturn-to-zero (NRZ) encoding. | | | With this encoding method, only a minimal amount of clocking information is available in the data stream in the form of transitions on bit-cell boundaries, which do not allow for self-clocking. | | | This field contains the data packet that is further defined in the SBN protocol. |
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http://www.nws.noaa.gov/noaaport/html/datalink.shtml
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| | CCNA Study Notes - OSI - Data Link Layer |
| | The receiving computer recalculates the CRC and compares it to the one sent with the data. | | | The transport layer adds a header indicating that an HTTP process is requested. | | | Packets and datagrams are converted into frames and the Data Link header is added. |
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http://defoenet.com/ccna/osi_l2.html
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| | Data Link Layer |
| | Data link layer algorithms may be embedded in the network hardware (rather than running as software process on a machine). | | | In general, computer algorithms don't have to be run as software on general-purpose machines. | | | If we allow any number of errors in data bits and in check bits, then no error-detection (or correction) method can guarantee to work, since any valid pattern can be transformed into any other valid pattern. |
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http://www.compapp.dcu.ie/~humphrys/Notes/Networks/data.link.html
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| | The Data Link Layer Protocols |
| | The primary station is responsible for the organisation of data flow and for the link level error recovery procedures. | | | The physical link has no inherent storage capacity, therefore the delay involved is the propagation delay over the link. | | | The implication of such a physical link is that the data bits are delivered in exactly the same order in which they are sent. |
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http://www.dsi.unive.it/~franz/reti/dll/Protocolli.html
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| | Data Link Layer Processing © AA VERSTRAETE |
| | The data link is the last layer in the protocol suite that treats the data as a logical data string held in the computer's main memory and processed by the communication's software. | | | The header and trailer are removed from the frame and then the packet is examined for low level transmission errors. | | | If no errors are found, the next layer is presented with the packet for further processing. |
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http://www.smeal.psu.edu/misweb/datacomm/ID/OSI_RDL.HTM
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| | The DataLink Layer |
| | This property is called data transparency and means that the transmission of the data does not corrupt the data no matter what bit patterns (or characters) it contains (this is a non-trivial problem and is usually done by the hardware at the physical level). | | | The host computers past data to/from the IMPS (interface message processors) which handle the communications over the physical communications link. | | | Example data structures and library routines required for data link layer |
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http://www.cse.dmu.ac.uk/~cfi/Networks/DataLink/DataLink0.htm
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| | The Data Link Layer |
| | The capability to send data to only the correct host was a huge advance in switching because collisions became much less likely. | | | The hosts on VLAN 1, on both switch A and B will have access to the router interface (which happens to be on another device) since they are all "trunked" together and share a broadcast domain. | | | If you can't ARP for a machine, you have to use a router, as we already know. |
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http://www.webopedia.com/DidYouKnow/Computer_Science/2006/data_link_layer.asp
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| | Data-Link Layer |
| | The data-link layer provides error-free transfer of data frames from one computer to another over the physical layer. | | | Establishment and termination of logical links (virtual-circuit connection) between two computers identified by their unique network adapter addresses. | | | Management of media access to determine when the computer is permitted to use the physical medium. |
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http://www.microsoft.com/resources/documentation/Windows/2000/server/reskit/en-us/cnet/cnfh_osi_ltkh.asp?frame=true
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| | The Data Link Layer |
| | It accomplishes this task by having the sender break the input data up into data frames (typically a few hundred bytes), transmit the frames sequentially, and process the acknowledgment frames sent back by the receiver. | | | If there is a chance that these bit patterns might occur in the data, special care must be taken to avoid confusion. | | | Frequently, flow regulation and error handling are integrated, for convenience. |
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http://www2.rad.com/networks/1994/osi/datalink.htm
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| | Data Link Layer |
| | Data is passed by each computer in one direction | | | SAP’s are defined in headers that identify the logical port assigned to the protocol | | | All encapsulated data plus the data link information |
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http://www.brazosport.cc.tx.us/~slannen/netess/chap6
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| | Chapter 6: Data Link Layer |
| | Error detection is performed by adding additional information to the data which might allow the receiver to recognize an error. | | | An example of controlled access is a central computer polling each terminal with an invitation to send data. | | | Forward error correction includes enough redundant data (preferably significantly less than 100% redundancy by volume) to correct many errors without retransmission. |
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http://telecomm.boisestate.edu/is380.f97/datalink.htm
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| | Data Link Layer Components |
| | To prevent more than one processor from simultaneously accessing certain critical data structures of the shared-memory pool, the model uses an indivisible test-and-set instruction to obtain exclusive use of a shared-memory data structure. | | | This is especially useful in heterogeneous environments where a PPP server may need to assign certain properties to the peer, such as the Maximum Receive Unit. | | | PPP can be used in two ways in the Tornado environment. |
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http://www.ia.agh.edu.pl/personal/pszwed/kss-lab/wind-docs/vxworks/netguide/c-dll.html
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| | Data-Link Layer - 2 |
| | Data has to be free of all errors to be useful. | | | There are a number of ways of trying to remove the errors introduced by the physical layer. | | | Builds on the transmission facility provided by the physical layer to transform it into a link that appears to the network layer above to be free of transmission errors. |
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http://www.eeng.dcu.ie/~murphyj/tc2/dc2000/tsld018.htm
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| | Chapter 7: The OSI Data-Link Layer |
| | This layer tells us how the network is physically accessed, how some errors are handled, how data flow is handled and how entities on the network are addressed. | | | Error Control allows the receiver to use the frame numbers in a window to let the sender know when a frame was not received or when the CRC check does not match. | | | Number of active devices - how many will the net support? |
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http://home.att.net/~s.k.vincent/250_7.htm
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| | NETBOOK - Q & A on Data Link Layer in OSI |
| | A network analyzer can tell from the values in the type field (small values are lengths, which mean an LLC/SNAP header is located in the first octets of the data area; large values are types, which mean no LLC/SNAP header is included). | | | A: Most installations still use DIX Ethernet encoding in which there is no LLC/SNAP header in the frame. | | | Q: When I use a network sniffer to capture Ethernet frames on a network that supports TCP/IP, I cannot locate the fields where LLC information are stored. |
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http://www.netbook.cs.purdue.edu/othrpags/qanda114.htm
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| | Data Link Layer Protocols |
| | Consists of data plus control bits (header information). | | | Positive Acknowledgement with Retransmission (PAR)--sender waits for positive acknowledgement before advancing to the next data item. | | | Important: TC sublayer must know about header information above it. |
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http://www.cs.wpi.edu/~cs4514/b98/week3-dllprot/week3-dllprot.html
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| | Webopedia: The 7 Layers of the OSI Model |
| | This layer provides transparent transfer of data between end systems, or hosts, and is responsible for end-to-end error recovery and flow control. | | | You are in the: Small Business Computing Channel | | | This layer provides switching and routing technologies, creating logical paths, known as virtual circuits, for transmitting data from node to node. |
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http://www.webopedia.com/quick_ref/OSI_Layers.asp
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| | ISA General Information |
| | This technical report acts as a tutorial addressing those who are not familiar with ISA's Fieldbus Data Link Layer (DLL) documents. | | | links separate parts of the ISA DLL documents relevant to either the same subject or to correlated items; and | | | presents the specific reasons why certain features in ISA's DLL documents are included; |
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http://www.isa.org/?template=Ecommerce/ProductDisplay.cfm&ProductID=2613
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| | Data link layer |
| | When the frame arrives the destination machine, it computes the check sum again if the newly computed checksum is different from the old one an error has been occured and the data link layer takes necessary steps to deal with it. | | | The usual approach is to break the bit stream into discrete frames and compute the check sum for each frame. | | | Data link layer has several functions to perform they are providing a well defined service to the network layer, determining how the bits of the physical layer are grouped into frames, dealing with transmission errors, regulating the flow of frames so that slow receivers are not swamped by fast senders, and general link management. |
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http://homepages.uel.ac.uk/u0214590/data.html
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| | Role of the Data-link layer |
| | buffering and copying the received data to a disk file) to accommodate the rate at which the sender is sending the data. | | | This is achieved by having appropriate error control and flow control algorithms. | | | The Data-link layer in the receiver extracts the data and passes the data to its Network layer. |
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http://www.cs.mu.oz.au/353/notes/node53.html
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| | ITPRC - Data Link |
| | Ryan's Gigabit Network and Distributed Computing Home Page - Collection of links to research projects on gigabit networking | | | Gigabit Ethernet Links Page - IEEE's links to Gigabit Ethernet Information | | | FDDI - System Level Description - A detailed white paper on FDDI technology |
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http://www.itprc.com/datalink.htm
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| | Data Link Layer and IEEE |
| | The ethernet standard data encapsulation method is defined by RFC 894. | | | IEEE 802 (RFC 1042) Message format consists of 3 sections plus data and CRC as follows: | | | RFC 1042 defines the IP to link layer data encapsulation for networks using the IEEE 802 standards. |
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http://www.comptechdoc.org/independent/networking/guide/netieee.html
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| | OSI Model - Data Link Layer |
| | The data link layer performs various functions depending upon the hardware protocol used, but has four primary functions: | | | The frame formatting issues such as stop and start bits, bit order, parity and other functions are handled here. | | | The CSMA/CD protocol that Ethernet uses to control access to the common network bus could be said to occur at the data link layer of the OSI model or could also be called a data link function. |
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http://www.inetdaemon.com/tutorials/theory/osi/data_link.shtml
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| | Define data link layer - a definition from Whatis.com |
| | It also ensures that incoming data has been received successfully by analyzing bit patterns at special places in the frames. | | | Go to Whatis.com for more computer terms and definitions | | | The Data-Link Layer is the protocol layer in a program that handles the moving of data in and out across a physical link in a network. |
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http://searchnetworking.techtarget.com/sDefinition/0,,sid7_gci211971,00.html
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| | Networking Technology - Questy's study guide |
| | - Controlling data flow between the transmitter and receiver. | | | Support our website, and get the reference book you need, use this link to find all your tech book needs: | | | The lower sub-layer of the Data Link layer, the Media Access Control (MAC), performs Data Link layer functions related to the Physical layer, such as controlling access and encoding data into a valid signaling format. |
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http://www.computerguru.net/tech/netw31.htm
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| | Data Link Layer |
| | SYN SYN Count(2 bytes) data characters …….. error detect codes | | | -To achieve Data Transparency, stuff 0 after every 5 consecutive 1's | | | -Receiver will also divide the data bits with the same Divisor and calculates |
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http://www.ecst.csuchico.edu/~sim/278/notes/NOTE9_1.htm
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| | The Data Link Layer |
| | Note: maximum thorughput is 18% of physical channel capacity | | | padding: used to insure data plus padding > 46 bytes | | | data link level addresses different from network layer addresses! |
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http://www-net.cs.umass.edu/cs653-1997/notes/ch7/ch7-1.htm
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| | ITworld.com - Data link layer protocols |
| | Find out why companies are moving from proprietary IT management tools to open source products such as Nagios, OpenNMS, Syslog NG and MRTG. | | | Interview: Robert Metcalfe, recipient, National Medal of Technology ITworld.com | | | Robert Frances Group believes that the enterprise data center is undergoing significant and sustained transformation
and that Azul Systems has delivered on a new approach to delivering processing and memory resources to enterprise applications... |
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http://www.itworld.com/Net/1747
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| | The Data Link Layer |
| | Several algorithms are available for use to acknowledge delivery of packages. | | | After the creation of the OSI model it was found necessary to expand the data link layer to take account of shared communication channels in LANs. | | | The logical link layer deals with the transmission of frames. |
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http://www.sju.edu/~jhodgson/netw/lolink.html
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| | The Data Link layer |
| | (See BSC as an example of a Data link level protocol | | | The provision of one or more data link connections between two network layer processes. | | | In practice no method can be 100% error free and the actual error rate contributes to the calculation of the quality of service. |
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http://www.scit.wlv.ac.uk/~jphb/comms/std.osirm2.html
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| | Java: Data link layer protocol |
| | Just don`t ask me about Database or GIU`s. | | | I'm developing a data link protocol using UDP in java. | | | You are here: Experts > Computing/Technology > Java > Java > Data link layer protocol |
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http://experts.about.com/q/Java-1046/Data-link-layer-protocol.htm
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| | Data Link Layer |
| | Flag end of frame, 1 byte = 01111110 | | | Purpose: to transfer data packets between directly connected nodes via the physical layer (wire, fiber, radio). | | | 01111110 becomes 01111101 01011110 (flag = escape, data XOR x20) |
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http://www.cs.fit.edu/~mmahoney/cse3103/datalink.html
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| | The Data Link Layer. |
| | Ethernet for example is a data link protocol that allows all hosts connected to the same link, hidden for example in a hub, to communicate with each other. | | | The second layer, Layer 2, the data link layer, is what enables hosts on the same link to communicate with each other. | | | Layer 2 protocols hide the details of the physical layer to hosts; Ethernet for example allows communication over such media as copper, fibre, and air, and at speeds of 10Mb/s, 100Mb/s, and 1Gb/s. |
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http://www.ee.vt.edu/~wells/rapport/node9.html
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| | Data Link Layer |
| | This is the layer where the "wire" is. |
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http://www.pandc.org/peter/presentations/aall2000/slide10.htm
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| | Data Link Layer (Linktionary term) |
| | Originally, data link protocols were designed for point-to-point links, and this is still the primary way that communication is handled, although shared LANs such as Ethernet require additional medium access control protocols to arbitrate access to the shared medium. | | | Therefore, it defines the protocols that directly interact with the physical components of the link, such as the network adapters and cable. | | | In the OSI (Open Systems Interconnection) model, the data link layer sits just above the physical layer. |
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http://www.linktionary.com/d/data_link_osi.html
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| | Data-link layer |
| | Providing addresses for devices is a function of the Data-link layer. | | | But before understanding device addresses we need to cover some more fundamental functions of the Data-link layer, namely error and flow control. | | | Note that although the Physical layer allows transmission of bits over a medium, it doesn't even specify to which device these bits are being transmitted! |
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http://www.cs.mu.oz.au/353/notes/node52.html
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| | Data Link Layer |
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The data link layer is responsible for transmitting packets of information across the link between hosts. | | | If the link is shared by many hosts (for example, a LAN) this layer also specifies how access to the media link is controlled. | | | A sublayer of the data link layer, called the medium access control (MAC) sublayer, addresses access issues. |
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http://www.uc.edu/sashtml/networks/chapa/sect1.htm
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| | Data Link Layer Sublayers |
| | In order to incorporate these methods into the overall network protocol structure the, Data Link Layer has been divided in LANs into 2 sublayers: | | | Logical Link Control (LLC), which implements full Data Link packet transmission services between any two nodes in the LAN | | | Media Access Layer (MAC), which regulates the access to the channel (using one of the access control methods) giving each node a fair chance to transmit it’s data |
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http://www.eeng.dcu.ie/~murphyj/tc2/dc2000/tsld213.htm
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| | data link layer |
| | Previous: Data Link Connection Identifier Next: data link level | | | Example protocols at this layer are ABP, Go Back N, SRP. | | | The data link layer is split into an upper sublayer, Logical Link Control (LLC), and a lower sublayer, Media Access Control (MAC). |
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http://burks.brighton.ac.uk/burks/foldoc/68/28.htm
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| | Data Link Layer |
| | OSI Data Link Layer is subdivided into two layers |
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http://home.ubalt.edu/abento/427/10baset/tsld009.htm
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| | Data Link Layer |
| | This particular document, SAE J1939-21, describes the data link layer using the CAN protocol with 29-bit Identifiers. | | | It is the intention of these documents to allow Electronic Control Units to communicate with each other by providing a standard architecture. | | | For SAE J1939 no alternative data link layers are permitted. |
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http://www.sae.org/servlets/productDetail?PROD_TYP=STD&PROD_CD=J1939/21_200104
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| | Data link layer |
| | The upper layers are described later in this file. | | | Initialization: PC sends sequences of U bytes at 9600 bps until the camera responds by sending its ID. Each sequence has a length of 2-8 bytes. | | | The following figure illustrates the lower layers of the protocol used by some Canon PowerShot cameras: |
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http://www.graphics.cornell.edu/~westin/canon/ch02s02.html
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