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Unformatted text preview: n ID of 0 means the client ignores
the field, since it would set this field to a random number if it was going to verify the returned
value in the response.)
Line 2 is the reply from the server. The fields filled in by the server are the client's IP address
(which tcpdump prints as the name proteus), the server's IP address (printed as the name
mercury), the IP address of a gateway (printed as the name mercury), and the name of a
After receiving the BOOTP reply, the client immediately issues an ARP request to see if
anyone else on the network has its IP address. The name proteus following who-has
corresponds to the target IP address (Figure 4.3), and the sender's IP address is set to 0.0.0.0. It
sends another identical ARP request 0.5 second later, and another one 0.5 second after that. In
the third ARP request (line 5) it changes the sender's IP address to be its own IP address. This
is a gratuitous ARP request (Section 4.7).
Line 6 shows that the client waits another 0.5 second and broadcasts another BOOTP request.
The only difference between this request and line 1 is that now the client puts its own IP
address in the IP header. It receives the same reply from the same server (line 7). The client
waits another 2 seconds and broadcasts yet another BOOTP request (line 8) and receives the
same reply from the same server.
The client then waits another 2 seconds and sends an ARP request for its server mercury (line
10). The ARP reply is received and the client immediately issues a TFTP read request for its
boot file (line 12). What follows are 2464 TFTP data packets and acknowledgments. The
amount of data transferred is 512 x 2463+224 = 1,261,280 bytes. This loads the operating file:///D|/Documents%20and%20Settings/bigini/Documenti/homenet2run/tcpip/tcp-ip-illustrated/bootp.htm (5 of 9) [12/09/2001 14.47.08] Chapter 16. BOOTP: Bootstrap Protocol system into the X terminal. We have deleted most of the TFTP lines from Figure 16.3.
One thing to notice, when comparing this TFTP exchange with Figure 15.2,...
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This test prep was uploaded on 04/04/2014 for the course ECE EL5373 taught by Professor Guoyang during the Spring '12 term at NYU Poly.
- Spring '12