TCP IP Illustrated

2521334 110 ms 120 ms 110 ms this time the ip address

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Unformatted text preview: ackets 1 bsdi ( 110 ms 110 ms 110 ms 2 svr4 ( 110 ms 120 ms 110 ms This time the IP address printed for host bsdi is, the SLIP interface, while previously it was, the Ethernet interface. Since traceroute also tries to print the name associated with an IP address, the names can change. (In our example both interfaces on bsdi have the same name.) Consider Figure 8.3. It shows two local area networks with a router connected to each LAN. The two routers are connected with a point-to-point link. If we run traceroute from a host on the left LAN to a host on the right LAN, the IP addresses found for the routers will be if1 and if3. But going the other way will print the IP addresses if4 and if2. The two interfaces if2 and if3 share the same network ID, while the other two interfaces have different network IDs. Figure 8.3 Identification of interfaces printed by traceroute. Finally, across wide area networks the traceroute output is much easier to comprehend if the IP addresses are printed as readable domain names, instead of as IP addresses. But since the only piece of information traceroute has when it receives the ICMP message is an IP address, it does a "reverse name lookup" to find the name, given the IP address. file:///D|/Documents%20and%20Settings/bigini/Docu...homenet2run/tcpip/tcp-ip-illustrated/tracerou.htm (6 of 17) [12/09/2001 14.46.47] Traceroute Program This requires the administrator responsible for that router or host to configure their reverse name lookup function correctly (which isn't always the case). We describe how an IP address is converted to a name using the DNS in Section 14.5. 8.4 WAN Output The output shown earlier for our small internet is adequate for examining the protocols in action, but more a realistic use of traceroute involves larger internets such as the worldwide Internet. Figure 8.4 is from the host sun to the Network Information Center, the NIC. sun % traceroute traceroute...
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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.

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