Installing and Administering Internet Services

168 Chapter 5
Configuring TFTP and BOOTP Servers
How BOOTP Works
Figure 5-1 shows an example of a bootrequest that is relayed from server
A to server B to server C. Server C finds the client’s boot information in
its database, and sends the bootreply back to server A. Server A then
sends the bootreply to the client.
Figure 5-1 Bootrequest Relay Example
NOTE BOOTP clients can be booted over a gateway; however, the BOOTP
server with the relay information for the client must be on the same side
of the gateway as the client.
File Transfer
The second phase, file transfer by the BOOTP client using TFTP, is
optional. Some BOOTP clients use BOOTP only for IP address resolution
and do not use TFTP. If the boot file is transferred, it must be publicly
available.
Client 1
Server A
Server B
Server C
Bootrequest
Bootreply
2
1