TCP IP Illustrated

The flag link0 for the slip interface is the

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Unformatted text preview: is received from the other end, and LINK2, which causes all outgoing ICMP packets to be thrown away. We'll look at the destination address of this SLIP link in Section 4.6. A comment in the installation instructions gives the reason for this last option: "This shouldn't have to be set, but some cretin pinging you can drive your throughput to zero." bsdi is the other router. Since the -a option is a SunOS feature, we have to execute ifconfig multiple times, specifying the interface name as an argument: bsdi % /sbin/ifconfig weO we0: flags=863<UP, BROADCAST, NOTRAILERS, RUNNING, SIMPLEX> inet 140.252.13.35 netmask ffffffe0 broadcast 140.252.13.63 bsdi % /sbin/ifconfig slO sl0 : flags=1011<UP, POINTOPOINT, LINKO inet 140.252.13.66 -> 140.252.13.65 netmask ffffffe0 Here we see a new option for the Ethernet interface (we0): SIMPLEX. This 4.4BSD flag specifies that the interface can't hear its own transmissions. It is set in BSD/386 for all the Ethernet interfaces. When set, if the interface is sending a frame to the broadcast address, a copy is made for the local host and sent to the loopback address. (We show an example of this feature in Section 6.3.) On the host slip the configuration of the SLIP interface is nearly identical to the output shown above on bsdi, with the exception that the IP addresses of the two ends are swapped: slip % /sbin/ifconfig slO sl0 : flags=1011<UP, POINTOPOINT, LINK0 inet 140.252.13.65 --> 140.252.13.66 netmask ffffffe0 file:///D|/Documents%20and%20Settings/bigini/Docu...homenet2run/tcpip/tcp-ip-illustrated/ip_inter.htm (16 of 19) [12/09/2001 14.46.37] Chapter 3. IP: Internet Protocol The final interface is the Ethernet interface on the host svr4. It is similar to the Ethernet output shown earlier, except that SVR4's version of ifconfig doesn't print the RUNNING flag: svr4 % /usr/sbin/ifconfig emdO emdO: flags=23<UP, BROADCAST, NOTRAILERS> inet 140.252.13.34 netmask ffffffe0 broadcast 140.252.13.63 The ifconfig command normally supports other protocol families (other than TCP/IP) and has numerous additional o...
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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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