TCP IP Illustrated

8 if we specify the v option we can see the ttl value

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Unformatted text preview: this. 8.5 We can run tcpdump on the SLIP link between sun and netb when running the example from Figure 8.8. If we specify the -v option we can see the TTL value of the returned ICMP messages. Doing this shows the incoming TTL from netb to be 255, from butch it's 253, from Gabby it's 252, and from enssl42.UT.westnet.net it's 249. Does this give any additional information about whether there really are some missing routers? 8.6 Both SunOS and SVR4 provide a version of ping with a -l option that provides a loose source route. The manual pages state that it's intended to be used with the -R option (which specifies the record route option). If you have access to either of these systems, try these two options together. What's happening? If you can watch the datagrams with tcpdump, describe what's going on. 8.7 Compare the ways ping and traceroute handle multiple instances of the client on the same host. 8.8 Compare the ways ping and traceroute measure the round-trip time. 8.9 We said traceroute picks the starting UDP destination port number at 33435 and increments this by one for each packet sent. In Section 1.9 we said ephemeral port numbers are normally between 1024 and 5000, making it unlikely that Traceroute's destination port is in use on the destination host. Is this still true under Solaris 2.2? (Hint: Read Section E.4.) 8.10 Read RFC 1393 [Malkin 1993b] for a proposed alternative way of determining the path to a destination. What are its advantages and disadvantages? file:///D|/Documents%20and%20Settings/bigini/Docu...homenet2run/tcpip/tcp-ip-illustrated/tracerou.htm (17 of 17) [12/09/2001 14.46.48] Chapter 9. IP Routing IP Routing 9.1 Introduction Routing is one of the most important functions of IP. Figure 9.1 shows a simplified view of the processing done at the IP layer. Datagrams to be routed can be generated either on the local host or on some other host. In the latter case this host must be configured to act as a router, or datagrams received through the network interfaces that are not ours are dropped (i....
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