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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 22.214.171.124 netmask ffffffe0 broadcast 126.96.36.199
bsdi % /sbin/ifconfig slO
sl0 : flags=1011<UP, POINTOPOINT, LINKO
inet 188.8.131.52 -> 184.108.40.206 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
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 220.127.116.11 --> 18.104.22.168 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 22.214.171.124 netmask ffffffe0 broadcast 126.96.36.199
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.
- Spring '12