by Matthew G. Naugle
Wiley Computer Publishing, John Wiley & Sons, Inc.
ISBN: 0471196568 Pub Date: 11/01/98
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Illustrated TCP/IP
by Matthew G. Naugle Wiley Computer Publishing, John Wiley & Sons, Inc. ISBN: 0471196568 Pub Date: 11/01/98 |
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The basic operation is as follows:
There is a single packet type exchanged between the client and the server. One field in the packet is called the opcode and can have one of two values: BOOTREQUEST or BOOTREPLY. The client broadcasts a BOOTREQUEST packet that contains the client’s hardware address and its IP address if known. The BOOTREQUEST may contain the name of the server the client wishes to respond. This is to force the BOOTREQUEST packet to a particular server from which to obtain its information. This may occur if there are many servers on the network or if there is more than one image (older/newer) version that could be sent to the client. Inside the BOOTREQUEST may be a generic filename to be booted. Simple names like ipboot or unixboot are used. When the server replies with a BOOTREPLY, it replaces this entry with the full pathname by which the file can be located on that server.
If the client does not know its IP address, the server must possess a database of MAC-to-IP address mappings. Once a match is found, this IP address is placed in a field in the BOOTREPLY packet.
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