6 bootstrap bootp server 1926030100 eth2 da

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Unformatted text preview: r Eth2 DA = FFFF.FFFF.FFFF DA = SA = DPort = 68 UDP SPort = 67 Request-ID = 77 B Client IP = O MAC = A O Your IP = T Server IP = P Image File = /tftpboot/dl.img IP Thank You ! BOOTP Client (C) Herbert Haas 2005/03/11 TFTP Server 7 After the BOOTP server receipt the request from the BOOTP client, he uses his fixed mapping method (MAC A address = ….. IP address) to offer the client an IP address. The BOOTP server also sends the client information about the TFTP server and the name of the configuration file. 7 Principles Separation of the boot task into a BOOTP-part and a TFTP-part BOOTP server only needs to maintain a small database ! Image- and configuration-files can be stored on another machine BOOTP client is responsible for error detection (C) Herbert Haas 2005/03/11 8 After an error detection (timeout) there will be a retransmission. The timeout is selected randomly from a special interval, which is increased as error last on -> avoiding network overload. For the error detection the UDP and a checksum is used. Also the IP datagram has the “Do Not Fragment Bit” set to 1. 8 BOOTP - Message Format OP HTYPE HLEN HOPS TRANSACTION ID SECONDS RESERVED CLIENT IP ADDRESS YOUR IP ADDRESS SERVER IP ADDRESS ROUTER IP ADDRESS CLIENT HARDWARE ADDRESS (16 Octets) SERVER HOST NAME (64 Octets) BOOTFILENAME (128 Octets) VENDOR SPECIFIC AREA (64 Octets) (C) Herbert Haas 2005/03/11 9 In the picture above you see the BOOTP message format. One line is 4 bytes long. Note the 64-octet vendor specific area at the bottom of the frame. This space can be used for various additional messages and will be extended by DHCP. In the middle part (red) the most important information is carried, which is the assigned IP address, the IP address of a server from which this client can boot, and an optional router IP address if this server is located on another subnet. The detailed meaning of each fie...
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This document was uploaded on 02/12/2014.

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